Emission Rates of Multiple Air Pollutants Generated from Chinese Residential Cooking

Indoor cooking and cleaning as a source of outdoor air pollution in urban environments

Indoor sources of air pollution, such as from cooking and cleaning, play a key role in indoor gas-phase chemistry. The focus of the impact of these activities on air quality tends to be indoors, with less attention given to the impact on air quality outside buildings. This study uses the INdoor CHEmical Model in Python (INCHEM-Py) and the Advanced Dispersion Modelling System (ADMS) to quantify the impact cooking and cleaning have on indoor and outdoor air quality for an idealised street of houses. INCHEM-Py has been developed to determine the concentrations of 106 indoor volatile organic compounds at the point they leave a building (defined as near-field concentrations). For a simulated 140 m long street with 10 equi-distant houses undertaking cooking and cleaning activities, the maximum downwind concentration of acetaldehyde increases from a background value of 0.1 ppb to 0.9 ppb post-cooking, whilst the maximum downwind chloroform concentrations increase from 1.2 to 6.2 ppt after cleaning. Although emissions to outdoors are higher when cooking and cleaning happen indoors, the contribution of these activities to total UK emissions of volatile organic compounds is low (less than 1%), and comprise about a quarter of those emitted from traffic across the UK. It is important to quantify these emissions, particularly as continued vehicle technology improvements lead to lower direct emissions outdoors, making indoor emissions relatively more important. Understanding how indoor pollution can affect outdoor environments, will allow better mitigation measures to be designed in the future that can take into account all sources of pollution that contribute to human exposure.

Indoor Emissions Contributed the Majority of Ultrafine Particles in Chinese Urban Residences

Ultrafine particle (UFP) pollution should be controlled to reduce its effects on health. The design of control measures is limited owing to the uncertainty of source contributions in Chinese residences, where indoor UFP pollution is more severe than in Western residences. Herein, a source-specific, time-dependent UFP concentration model was developed by applying an infiltration factor model incorporating coagulation effects. A Monte Carlo framework with the UFP concentration model was employed to estimate the probabilistic distribution of source contributions in Chinese residences. The input parameter distributions were determined based on our survey and previous studies. The annually averaged indoor UFP concentration was estimated at (2.75 ± 1.71) × 104 #/cm3, ranging from 2.35 × 103 to 1.27 × 105 #/cm3 outside the kitchen, and at (5.48 ± 3.08) × 104 #/cm3, ranging from 2.90 × 103 to 1.94 × 105 #/cm3 in the kitchen. Indoor sources contributed more to indoor UFPs, accounting for 61% in the nonkitchen and 80% in the kitchen, surpassing their contribution to indoor PM2.5 in Chinese residences. Meanwhile, the indoor UFP emission contributions were higher than those in the United States, Canada, and Germany, owing to higher emissions from cooking and cigarette smoking. These results will aid in elucidating human exposure to UFPs and in designing more targeted control measures.

Experimental evaluation of the impact of ventilation on cooking-generated fine particulate matter in a Chinese apartment kitchen and adjacent room

Cooking is one of the major contributors to indoor pollution. Fine particulate matter (PM2.5) produced during cooking commonly mix into adjacent rooms and elevates indoor PM2.5 concentrations. The risk of human exposure to cooking-generated PM2.5 is mainly related to the exposure duration and particulate matter (PM) concentration. The PM2.5 concentration is influenced by cooking methods and ventilation patterns. Range hoods and open windows are conventional strategies for lowering the concentration of cooking-generated particles. To decrease PM emissions, kitchen air supply systems have been proposed, providing alternative possibilities for kitchen ventilation patterns. The effects of cooking methods, air supply systems, range hoods, and windows on PM2.5 concentrations must be analyzed and compared. To understand and provide advice on reducing exposure to PM2.5 due to cooking activities, we measured the PM2.5 mass concentration in a kitchen and adjacent room during cooking. The identified factors, including cooking method, range hood use, window status, and air supply system, were varied based on orthogonal design. The delay time between the PM2.5 peak in the kitchen and that in the adjacent room was determined. The degree of exposure risk for cooking-generated PM2.5 was evaluated using the mean exposure dose. The results indicated that the mean PM2.5 mass concentration in the kitchen ranged from 22 to 2296 μg/m3. In descending order, the factors affecting the indoor PM2.5 concentration in the apartment studied were range hood use, cooking methods, window status, and air supply system. The PM2.5 peak in the adjacent room occurred 200-800 s later than that in the kitchen. Other conditions being constant in these experiments, the use of range hoods, air supply systems, and windows reduce exposure doses by 90%, 37%, and 51%, respectively. These research results provide insights for reducing human exposure to cooking-generated PM2.5.

Species profile of volatile organic compounds emission and health risk assessment from typical indoor events in daycare centers

Daycare centers (DCCs) play an instrumental role in early childhood development, making them a significant indoor environment for a large number of children globally. Amidst routine DCC activities, young children are exposed to a myriad of volatile organic compounds (VOCs), potentially impacting their health. Therefore, this study aims to investigate the VOC emissions during typical DCCs activities and evaluate respective health risk assessments. Employing a full-scale experimental setup within a well-controlled climate chamber, research was conducted into VOC emissions during three typical DCC events: arts-and-crafts (painting, gluing, modeling), cleaning, and sleeping activities tied to mattresses. The research identified 96 distinct VOCs, grouped into twelve categories, from 20 different events examined. Each event exhibited a unique VOC fingerprint, pinpointing potential source tracers. Also, significant variations in VOC emissions from different events were demonstrated. For instance, under cool & dry conditions, acrylic painting recorded high total VOC concentrations of 808 μg/m3, whereas poster painting showed only 58 μg/m3. Given these disparities, the study emphasizes the critical need for carefully selecting arts-and-crafts materials and cleaning agents in DCCs to effectively reduce VOC exposure. It suggests ventilating new mattresses before use and regular mattress check-ups to mitigate VOCs exposure during naps. Importantly, it revealed that certain events resulted in VOC levels exceeding the 10-5 cancer risk thresholds for younger children. Specifically, tetrachloroethylene and styrene from used mattresses in cool & dry conditions, ethylene oxide from new mattresses in warm & humid conditions, and styrene, during sand modeling in both conditions, were the key compounds contributing to this risk. These findings highlight the critical need for age-specific health risk assessments in DCCs. This study highlights the significance of understanding the profiles of VOC emissions from indoor events in DCCs, emphasizing potential health implications and laying a solid foundation for future investigations in this field.

Composition analysis and health risk assessment of the hazardous compounds in cooking fumes emitted from heated soybean oils with different refining levels

The cooking fumes generated from thermal cooking oils contains various of hazardous components and shows deleterious health effects. The edible oil refining is designed to improve the oil quality and safety. While, there remains unknown about the connections between the characteristics and health risks of the cooking fumes and oils with different refining levels. In this study, the hazardous compounds, including aldehydes, ketones, polycyclic aromatic hydrocarbons (PAHs), and particulate matter (PM) in the fumes emitted from heated soybean oils with different refining levels were characterized, and their health risks were assessed. Results demonstrated that the concentration range of aldehydes and ketones (from 328.06 ± 24.64 to 796.52 ± 29.67 μg/m3), PAHs (from 4.39 ± 0.19 to 7.86 ± 0.51 μg/m3), and PM (from 0.36 ± 0.14 to 5.08 ± 0.15 mg/m3) varied among soybean oil with different refining levels, respectively. The neutralized oil showed the highest concentration of aldehydes and ketones, whereas the refined oil showed the lowest. The highest concentration levels of PAHs and PM were observed in fumes emitted from crude oil. A highly significant (p < 0.001) positive correlation between the acid value of cooking oil and the concentrations of PM was found, suggesting that removing free fatty acids is critical for mitigating PM concentration in cooking fumes. Additionally, the incremental lifetime cancer risk (ILCR) values of PAHs and aldehydes were 5.60 × 10-4 to 8.66 × 10-5 and 5.60 × 10-4 to 8.66 × 10-5, respectively, which were substantially higher than the acceptable levels (1.0 × 10-6) established by US EPA. The present study quantifies the impact of edible oil refining on hazardous compound emissions and provides a theoretical basis for controlling the health risks of cooking fumes via precise edible oil processing.

Large-scale spatiotemporal deep learning predicting urban residential indoor PM2.5 concentration

Indoor PM2.5 pollution is one of the leading causes of death and disease worldwide. As monitoring indoor PM2.5 concentrations on a large scale is challenging, it is urgent to assess population-level exposure and related health risks to develop an easy-to-use and generalized model to predict indoor PM2.5 concentrations and spatiotemporal variations at the global level. Existing machine learning models of indoor PM2.5 are prone to deliver single-point predictions, and their input strategies are not widely applicable. Here, we developed a Bayesian neural network (BNN) model for predicting the distribution of daily average urban residential PM2.5 concentration based on multiple data sources available from nationwide comprehensive sensor-monitoring records in China. The BNN model showed good performance with a 10-fold cross-validation R2 of 0.70, mean-absolute-error of 9.45 μg/m3, root-mean-square error of 13.3 μg/m3, and 95 % prediction interval coverage of 85 %. To demonstrate the application process, this model was applied to predict indoor PM2.5 concentrations on a large spatiotemporal scale. Our modeled population-weighted annual indoor PM2.5 concentration for China in 2019 was 22.8 μg/m3, far exceeding the WHO standard. The validity of the model at the population level can be further bolstered, making it valuable for assessing and managing indoor air pollution-related health risks.

Particulate Matter and Volatile Organic Compound Emissions Generated from a Domestic Air Fryer

Air frying has become a popular cooking method for domestic cooking, but the level of released indoor air pollutants is poorly understood. In this work, we compared particle and gas phase emission factors (EF) and particle size distributions between cooking with a domestic air fryer and a pan for a variety of foods. The PM10 EFs of air frying chicken wings and breast were higher than pan cooking by a factor of 2.1 and 5.4, respectively. On the other hand, a higher PM10 emission factor from air frying can be achieved by increasing the amount of oil to levels similar to or above those from pan-frying for French fries and asparagus. We propose that higher temperature and greater turbulence lead to higher PM10 EFs for cooking with the air fryer compared with the pan for the same mass of oil added. EFs of volatile organic compounds (VOCs) are also generally higher for cooking with the air fryer compared with the pan: 2.5 times higher for French fries and 4.8 times higher for chicken breast. Our study highlights the potential risk of higher indoor PM10 levels associated with domestic air frying under certain cases and proposes possible mitigation measures.

Higher Toxicity of Gaseous Organics Relative to Particulate Matters Emitted from Typical Cooking Processes

Cooking emission is known to be a significant anthropogenic source of air pollution in urban areas, but its toxicities are still unclear. This study addressed the toxicities of fine particulate matter (PM2.5) and gaseous organics by combining chemical fingerprinting analysis with cellular assessments. The cytotoxicity and reactive oxygen species activity of gaseous organics were ∼1.9 and ∼8.3 times higher than those of PM2.5, respectively. Moreover, these values of per unit mass PM2.5 were ∼7.1 and ∼15.7 times higher than those collected from ambient air in Shanghai. The total oleic acid equivalent quantities for carcinogenic and toxic respiratory effects of gaseous organics, as estimated using predictive models based on quantitative structure-property relationships, were 1686 ± 803 and 430 ± 176 μg/mg PM2.5, respectively. Both predicted toxicities were higher than those of particulate organics, consistent with cellular assessment. These health risks are primarily attributed to the high relative content and toxic equivalency factor of the organic compounds present in the gas phase, including 7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione, 2-ethylhexanoic acid, and 2-phenoxyethoxybenzene. Furthermore, these compounds and fatty acids were identified as prominent chemical markers of cooking-related emissions. The obtained results highlight the importance of control measures for cooking-emitted gaseous organics to reduce the personal exposure risks.

Emission and capture characteristics of Chinese cooking-related fine particles

Cooking can emit high concentrations of particles and gaseous pollutants. Cooking has contributed to the major source of indoor air pollutants, especially for particle pollutants in residential buildings. Many studies already analyzed the emission characteristics of Chinese cooking-related UFPs and PM2.5, while less for the fine particle size distributions. Currently, the fine particle emission characteristics of Chinese cooking need to be further investigated, since the mass size distribution of Chinese cooking is dominated by fine particles. This study determined the emission characteristics of PM1 and fine particles from three Chinese cooking methods. The capture efficiencies of particles were also measured by a modified indirect approach, including the impact of particle decay. The results showed that stir-fried vegetable and pan-fried meat dishes generated more fine particles at 0.542-1.5 μm. Besides, pan-fried and deep-fried meat dishes produce a higher generation of PM1. The fine particles (0.542-10 μm) number-based and volume-based size distributions of six dishes both presented a monodisperse behavior. The cooking methods are not a sensitive factor to the volume frequency of fine particle ranging from 0.542 to 10 μm. The averaged volume median and mode diameter for six typical Chinese dishes are 2.5 μm and 3.3 μm, respectively. The Sauter and DeBroukere mean diameter is 4.7 μm and 5.6 μm, respectively. The decay of fine particles increases with the particle diameter. The impact of particle decay on capture efficiency for 2-3 μm particles is about 5%. The capture efficiencies of pan-fried and deep-fried meat dishes are lower than that of vegetable dishes. In contrast, the capture efficiency for stir-fried meat dishes is higher than that of vegetable dishes. The capture efficiency for PM1 and 0.542-5 μm particles from six typical Chinese dishes were 60-90% on the IEC recommended exhaust flowrate.

Impact of NO2 emissions from household heating systems with wall-mounted gas stoves on indoor and ambient air quality in Chinese urban areas

Nitrogen dioxide (NO2) has been discussed as a typical indoor pollutant for decades. As an increasingly popular heating method, household heating system (HHS) with wall-mounted natural gas stoves has led to a continuous increase in the emission of NO2. The absence of legal regulations and strict limits for NO2 emissions from wall-mounted gas stoves has led to a significant exceedance of indoor NO2 concentrations beyond the permissible value. However, this issue is rarely taken into consideration. In this study, we present the first report on NO2 emissions from wall-mounted gas stoves for household heating and their impact on indoor and ambient air quality in Chinese urban areas based on in-situ measurements and numerical simulations. On heating days, the observed indoor NO2 concentration is within 80-200 μg/m3, much higher than the outdoor atmospheric concentration. With a low emission grade of the wall-mounted gas stoves, it is estimated that >10 % of residents in a typical residential building area are exposed to a high NO2 concentration of >200 μg/m3, and >50 % of residents are exposed to a concentration of >80 μg/m3. In addition, the indoor NO2 concentration shows an obvious non-uniform distribution with the floor in residential buildings. The NO2 emission from residential natural gas heating also shows an obvious impact on the microenvironment around buildings, which is primarily determined by the emission grade of the stoves. The findings highlight that HHS has become a non-negligible source of indoor NO2 pollution in China. It is urgently necessary to formulate NO2 emission limit standards for wall-mounted gas stoves in Chinese urban areas and upgrade traditional natural gas heaters with efficient emission reduction technologies.

Exposure to cooking fumes is associated with perturbations in nasal microbiota composition: A pilot study

Air pollution is one of the leading causes of overall mortality globally. Cooking emissions are a major source of fine particulate matter (PM2.5). However, studies on their potential perturbations on the nasal microbiota as well as their association with respiratory health are lacking. This pilot study aims to assess the environmental air quality among occupational cooks and its associations with nasal microbiota and respiratory symptoms. A total of 20 cooks (exposed) and 20 unexposed controls (mainly office workers), were recruited in Singapore from 2019 to 2021. Information on sociodemographic factors, cooking methods, and self-reported respiratory symptoms were collected using a questionnaire. Personal PM2.5 concentrations and reactive oxygen species (ROS) levels were measured using portable sensors and filter samplers. DNA was extracted from nasal swabs and sequenced using 16s sequencing. Alpha-diversity and beta-diversity were calculated, and between-group variation analysis of species was performed. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between exposure groups and self-reported respiratory symptoms. Higher daily mean PM2.5 (P = 2 × 10-7) and environmental ROS exposure (P = 3.25 × 10-7) were observed in the exposed group. Alpha diversity of the nasal microbiota between the two groups was not significantly different. However, beta diversity was significantly different (unweighted UniFrac P = 1.11 × 10-5, weighted UniFrac P = 5.42 × 10-6) between the two exposure groups. In addition, certain taxa of bacteria were slightly more abundant in the exposed group compared to unexposed controls. There were no significant associations between the exposure groups and self-reported respiratory symptoms. In summary, the exposed group had higher PM2.5 and ROS exposure levels and altered nasal microbiotas as compared to unexposed controls, though further studies are required to replicate these findings in a larger population.

Distinct urban-rural gradients of air NO2 and SO2 concentrations in response to emission reductions during 2015-2022 in Beijing, China

Nitrogen dioxide (NO2) and sulfur dioxide (SO2) are two major air pollutants in urban environment. Emission reduction policies have thus been implemented to improve urban air quality, especially in the metropolises. However, it remains unclear whether the air concentrations of NO2 and SO2 in and around large cities follow a same spatial pattern and how their characteristics change over time in response to the emission reductions. Using ground-based monitoring datasets of air NO2 and SO2 concentrations in Beijing, China, we tested the hypothesis of urban air pollutant islands and evaluated their seasonal and inter-annual variations during 2015-2022. The results showed that air NO2 concentrations increased significantly towards the urban core, being in line with the hypothesis of urban air pollutant island, while air SO2 concentrations showed no such spatial patterns. The urban air NO2 island varied seasonally, with larger radius and higher air NO2 concentrations in spring and winter. In response to the emission reduction, the annual mean radius of the urban air NO2 island showed a rapid decrease from 45.8 km to zero km during the study period. The annual mean air NO2 concentration at the urban core showed a linear decrease at a rate of 4.5 μg m-3 yr-1. In contrast, air SO2 concentration decreased nonlinearly over time and showed a legacy in comparison to the emission reduction. Our findings suggest different urban-rural gradients of air NO2 and SO2 concentrations and highlight their distinct responses to the regional reductions of anthropogenic emissions.

Temperature-dependent particle number emission rates and emission characteristics during heating processes of edible oils

The goal of this research is to investigate the temperature-dependent emission rates of particle numbers and emission characteristics during oil heating. Seven regularly used edible oils were studied in a variety of tests to attain this objective. First, total particle number emission rates ranging from 10 nm to 1 μm were measured, followed by an examination within six size intervals from 0.3 μm to 10 μm. Following that, the impacts of oil volume and oil surface area on the emission rate were investigated, and multiple regression models were developed based on the results. The results showed that corn, sunflower and soybean oils had higher emission rates than other oils above 200 °C, with peak values of 8.22 × 109#/s, 8.19 × 109#/s and 8.17 × 109#/s, respectively. Additionally, peanut and rice oils were observed to emit the most particles larger than 0.3 μm, followed by medium-emission (rapeseed and olive oils) and low-emission oils (corn, sunflower and soybean oils). In most cases, oil temperature (T) has the most significant influence on the emission rate during the smoking stage, but its influence was not as pronounced in the moderate smoking stage. The models obtained are all statistically significant (P < 0.001), with R2 values greater than 0.9, and the classical assumption test concluded that regressions were in accordance with the classical assumptions regarding normality, multicollinearity, and heteroscedasticity. In general, low oil volume and large oil surface area were more recommended for cooking to mitigate UFPs emission.

Dopant Site Engineering on 2D Co3O4 Enables Enhanced Toluene Oxidation in a Wide Temperature Range

Development of cost-effective oxide catalysts holds the key to the removal of toluene, one of the most important volatile organic compounds. However, the catalysts follow varied working mechanisms at different reaction temperatures, posing a challenge to achieving efficient toluene removal over a wide temperature range. Here we report an agitation-assisted molten salt method, which achieves the rational doping on a two-dimensional Co3O4 catalyst and forms two different structures of active sites to enhance catalytic oxidation of toluene in specific temperature intervals, enabling a facile tandem design for working in a wide temperature range. Specifically, Co3O4 is doped with Cu at the octahedral site (Cu-Co3O4) and Zn at the tetrahedral site (Zn-Co3O4) to form CuOh-O-CoTe and ZnTe-O-CoOh structures on the surface, respectively. Mechanistic studies reveal the different working mechanisms of these two active sites toward remarkable performance enhancement at specific temperature intervals, and the improved performance derived from accelerated consumption of intermediates adsorbed on the catalyst surface. Taken together, Cu-Co3O4 and Zn-Co3O4 achieve excellent toluene purification performance over a wide temperature range. This work provides insights into the mechanism-oriented design of active sites at the atomic level.

Effectiveness of a covered oil-free cooking process on the abatement of air pollutants from cooking meats

Cooking events can generate household air pollutants that deteriorate indoor air quality (IAQ), which poses a threat to human health and well-being. In this study, the emission characteristics and emission factors (EFs) of air pollutants of different meats (beef, lamb, chicken, pork, and fish) cooked by a novel oil-free process and common with-oil processes were investigated. Oil-free cooking tends to emit lower total volatile organic compound (TVOC) levels and fewer submicron smoke particles and can reduce the intake of fat and calories. However, TVOC emissions during oil-free cooking were significantly different, and the lamb EFs were nearly 8 times higher than those during with-oil cooking. The particle-bound polycyclic aromatic hydrocarbon (ƩPPAH) and benzo(a)pyrene-equivalent (ƩBaPeq) EFs during with-oil cooking ranged from 76.1 to 140.5 ng/g and 7.7-12.4 ng/g, respectively, while those during oil-free cooking ranged from 41.0 to 176.6 ng/g and 5.4-47.6 ng/g, respectively. The ƩPPAH EFs of chicken, pork, and fish were lower during oil-free cooking than during cooking with oil. Furthermore, the ƩBaPeq EFs of beef, chicken, pork, and fish were lower during oil-free cooking than during cooking with oil. Therefore, it is recommended to use the oil-free method to cook chicken, pork, and fish to reduce ƩPPAH and ƩBaPeq emissions, but not recommended to cook lamb due to the increase of ƩBaPeq emissions. The with-oil uncovered cooking EFs of aldehydes ranged from 3.77 to 22.09 μg/g, and those of oil-free cooking ranged from 4.88 to 19.96 μg/g. The aldehyde EFs were lower during oil-free covered cooking than with-oil uncovered cooking for beef, chicken, and fish. This study provides a better realizing of new cooking approaches for the reduction of cooking-induced emission, but further research on the effects of food composition (moisture and fat) and characteristics is needed.

Construction and evaluation of hourly average indoor PM2.5 concentration prediction models based on multiple types of places

Background

People usually spend most of their time indoors, so indoor fine particulate matter (PM2.5) concentrations are crucial for refining individual PM2.5 exposure evaluation. The development of indoor PM2.5 concentration prediction models is essential for the health risk assessment of PM2.5 in epidemiological studies involving large populations.

Methods

In this study, based on the monitoring data of multiple types of places, the classical multiple linear regression (MLR) method and random forest regression (RFR) algorithm of machine learning were used to develop hourly average indoor PM2.5 concentration prediction models. Indoor PM2.5 concentration data, which included 11,712 records from five types of places, were obtained by on-site monitoring. Moreover, the potential predictor variable data were derived from outdoor monitoring stations and meteorological databases. A ten-fold cross-validation was conducted to examine the performance of all proposed models.

Results

The final predictor variables incorporated in the MLR model were outdoor PM2.5 concentration, type of place, season, wind direction, surface wind speed, hour, precipitation, air pressure, and relative humidity. The ten-fold cross-validation results indicated that both models constructed had good predictive performance, with the determination coefficients (R2) of RFR and MLR were 72.20 and 60.35%, respectively. Generally, the RFR model had better predictive performance than the MLR model (RFR model developed using the same predictor variables as the MLR model, R2 = 71.86%). In terms of predictors, the importance results of predictor variables for both types of models suggested that outdoor PM2.5 concentration, type of place, season, hour, wind direction, and surface wind speed were the most important predictor variables.

Conclusion

In this research, hourly average indoor PM2.5 concentration prediction models based on multiple types of places were developed for the first time. Both the MLR and RFR models based on easily accessible indicators displayed promising predictive performance, in which the machine learning domain RFR model outperformed the classical MLR model, and this result suggests the potential application of RFR algorithms for indoor air pollutant concentration prediction.

Intermediate volatile organic compounds in Canadian residential air in winter: Implication to indoor air quality

Intermediate volatile organic compounds (IVOCs) have recently been characterized for their contributions to the formation of secondary organic aerosol in atmospheric air. However, IVOCs in air in various indoor environments have not been characterized yet. In this study, we characterized and measured IVOCs, volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), in residential indoor air in Ottawa, Canada. IVOCs, including n-alkanes, branched-chain alkanes (b-alkanes), unspecified complex mixtures (UCM) IVOCs, and oxygenated IVOCs (such as fatty acids), were found to have a large impact on indoor air quality. The results indicate that the indoor IVOCs behave differently from those in the outdoor environment. IVOCs in the studied residential air ranged from 14.4 to 69.0 μg/m³, with a geometric mean of 31.3 μg/m³, accounting for approximately 20% of the total organic compounds (IVOCs, VOCs and SVOCs) in indoor air. The total b-alkanes and UCM-IVOCs were found to have statistically significant positive correlations with indoor temperature but have no correlations with airborne particulate matter less than 2.5 μm (PM_2.5) as well as ozone (O₃) concentration. However, indoor oxygenated IVOCs behaved differently from b-alkanes and UCM-IVOCs, with a statistically significant positive correlation with indoor relative humidity but no correlation with other indoor environmental conditions.

Indoor and outdoor air quality impacts of cooking and cleaning emissions from a commercial kitchen

Gas and particulate emissions from commercial kitchens are important contributors to urban air quality. Not only are these emissions important for occupational exposure of kitchen staff, but they can also be vented to outdoors, causing uncertain health and environmental impacts. In this study, we chemically speciated volatile organic compounds and measured particulate matter mass concentrations in a well-ventilated commercial kitchen for two weeks, including during typical cooking and cleaning operations. From cooking, we observed a complex mixture of volatile organic gases dominated by oxygenated compounds commonly associated with the thermal degradation of cooking oils. Gas-phase chemicals existed at concentrations 2-7 orders of magnitude lower than their exposure limits, due to the high ventilation in the room (mean air change rate of 28 h^-1 during operating hours). During evening kitchen cleaning, we observed an increase in the signal of chlorinated gases from 1.1-9.0 times their values during daytime cooking. Particulate matter mass loadings tripled at these times. While exposure to cooking emissions in this indoor environment was reduced effectively by the high ventilation rate, exposure to particulate matter and chlorinated gases was elevated during evening cleaning periods. This emphasizes the need for careful consideration of ventilation rates and methods in commercial kitchen environments during all hours of kitchen operation.

Cooking methods and kitchen ventilation availability, usage, perceived performance and potential in Canadian homes

BACKGROUND

Cooking is a substantial contributor to air pollutant exposures in many residences. Effective use of kitchen ventilation can mitigate exposure; however, information on its availability, usage, and potential to increase its use across the population has been limited.

OBJECTIVE

This study aimed to obtain nationally representative information on cooking methods, kitchen ventilation availability and usage, and the potential for education to increase effective usage.

METHODS

An online survey was sent to a representative sample of Canadian homes to collect data on cooking methods, the presence and use of mechanical kitchen ventilation devices, perceived device performance, and willingness to implement mitigation strategies. Responses were weighted to match key demographic factors and analyzed using non-parametric statistics.

RESULTS

Among the 4500 respondents, 90% had mechanical ventilation devices over the cooktop (66% of which were vented to the outside), and 30% reported regularly using their devices. Devices were used most often for deep-frying, followed by stir-frying, sautéing or pan-frying, indoor grilling, boiling or steaming. Almost half reported rarely or never using their ventilation devices during baking or oven self-cleaning. Only 10% were fully satisfied with their devices. More frequent use was associated with the device being vented to the outdoors, having more than two speed settings, quiet operation if only one speed, covering over half of the cooktop, and higher perceived effectiveness. After being informed of the benefits of kitchen ventilation, 64% indicated they would consider using their devices more often, preferentially using back burners with ventilation, and/or using higher ventilation device settings when needed.

IMPACT

This study provides population-representative data on the most used cooking methods, kitchen ventilation availability and usage, and influencing factors in Canadian homes. Such data are needed for exposure assessments and evaluating the potential to mitigate cooking-related pollutant exposures via more effective use of kitchen ventilation. The data can be reasonably extrapolated to the United States, given the similarities in residential construction practices and cultural norms between the two countries.

Temperature-dependent particle mass emission rate during heating of edible oils and their regression models

Particulate matter emitted by heated cooking oil is hazardous to human health. To develop effective mitigation strategies, it is critical to know the amount of the emitted particles. The purpose of this research is to estimate the temperature-dependent particle mass emission rates of edible oils and to develop models for source strength based on the multiple linear regression method. First, this study examined seven commonly used oils by heating experiments. The emission rates of PM2.5 and PM10 were measured, and the effects of parameters such as oil volume and surface area on the emission rates were also analysed. Following that, the starting smoke points (Ts') and aggravating smoke points (Tss') of tested oils were determined. The results showed that oils with lower smoke points had greater emission rates. Notably, the experiments performed observed that peanut, rice, rapeseed and olive oil generated PM2.5 much faster at 240 °C (2.22, 1.50, 0.82 and 0.80 mg/s, respectively, at the highest emission conditions) than that of sunflower, soybean, and corn oil (0.15, 0.12 and 0.11 mg/s, respectively). The temperature, volume, and surface area of oils all had a significant impact on the particle mass emission rate, with oil temperature being the most influential. The regression models obtained were statistically significant (P < 0.001), with the majority of R² values greater than 0.85. Using sunflower, soybean and corn oils, which have higher smoke points and lower emission rates, and smaller pans for cooking is therefore recommended based on our research findings.

Emission characteristics and quantitative assessment of the health risks of cooking fumes during outdoor barbecuing

Given the increasing popularity of outdoor barbecue activities and the disregard for barbecue fumes, this study systematically investigated barbecue fume emission characteristics for three types of grilled meats. Particulate matter and volatile organic compounds (VOCs) were continuously measured, and polycyclic aromatic hydrocarbons (PAHs) were isolated from the particulate matter. Cooking emission concentrations depended strongly on the type of meat being cooked. Fine particles were the main particles detected in this study. Low and medium-weight PAHs were the dominant species for all cooking experiments. The mass concentration of total VOCs in the barbecue smoke of the three groups showed significant differences (p < 0.05) and was 1667.18 ± 10.49 μg/m³ in the chicken wing group, 904.03 ± 7.12 μg/m³ in the beef steak group, and 3653.37 ± 12.22 μg/m³ in the streaky pork group. The results of risk assessment showed that the toxicity equivalent quality (TEQ) of carcinogenic PAHs in the particulate matter was significantly higher in the streaky pork group than in the chicken wing and beef steak groups. The carcinogenic risk of benzene exceeds the US EPA standard (1.0E-6) in all types of fumes. Although the hazard index (HI) was below one in all groups for noncarcinogenic risks, it was not cause of optimism. We conjecture that only 500 g of streaky pork would exceed the noncarcinogenic risk limit, and the mass required for carcinogenic risk may be less. When barbecuing, it is essential to avoid high-fat foods and strictly control the fat quantity. This study quantifies the incremental risk of specific foods to consumers and will hopefully provide insight into the hazards of barbecue fumes.

Air Purifier Intervention to Remove Indoor PM2.5 in Urban China: A Cost-Effectiveness and Health Inequality Impact Study

Using air purifiers is an intervention to reduce exposure to fine particulate matter (PM_2.5) for health benefits. We performed a comprehensive simulation in urban China to estimate the cost-effectiveness of long-term use of air purifiers to remove indoor PM_2.5 from indoor and ambient air pollution in five intervention scenarios (S1-S5), where the indoor PM_2.5 targets were 35, 25, 15, 10, and 5 μg/m³, respectively. In scenarios S1 to S5, 5221 (95% uncertainty interval: 3886-6091), 6178 (4554-7242), 8599 (6255-10,109), 11,006 (7962-13,013), and 14,990 (10,888-17,610) thousand disability-adjusted-life-years (DALYs) can be avoided at the cost of 201 (199-204), 240 (238-243), 364 (360-369), 522 (515-530), and 921 (905-939) billion Chinese Yuan (CNY), respectively. A high disparity in per capita health benefits and costs was observed by city, which expanded with the decrease of the indoor PM_2.5 target. The net benefits of using purifiers in cities varied across scenarios. Cities with a lower ratio of annual average outdoor PM_2.5 concentration to gross domestic product (GDP) per capita tended to achieve higher net benefits in the scenario with a lower indoor PM_2.5 target. Controlling ambient PM_2.5 pollution and developing the economy can reduce the inequality in air purifier use across China.

Personal exposure to PM2.5 in different microenvironments and activities for retired adults in two megacities, China

Microenvironmental concentrations and time-activity patterns influence personal exposure to fine particulate matter (PM_2.5). However, the variations and contributions of PM_2.5 exposures from various microenvironments (MEs) and activities remain unclear. In this study, gravimetrically corrected real-time personal PM_2.5 measurements were collected during routine activities in different MEs from 66 non-smoking retired adults. Exposure data were collected for five consecutive days over two seasons in Nanjing (NJ) and Beijing (BJ), China. Measured PM_2.5 concentrations varied substantially both between and within different MEs and activities. The highest average concentrations were observed in restaurants (NJ: mean 192 μg/m³, SD 242 μg/m³; BJ: mean 91 μg/m³, SD 79 μg/m³) and were associated with sources such as passive smoking and cooking emissions. Overall, PM_2.5 concentrations in different MEs and activities were moderately to highly correlated with outdoor PM_2.5 concentrations (Spearman's r = 0.51-0.97) except in restaurants and during passive smoking. The at-home ME contributed approximately 85 % of the total PM_2.5 exposure, corresponding to the participants spending about 87 % of their time there. The majority of household exposures occurred during sleeping, cooking, and other home-based activities. Transportation accounted for <5 % of total exposure. Our results indicate that improving indoor air quality, especially residential indoors, is important to reduce personal exposure to PM_2.5.

Identification of Factors Determining Household PM2.5 Variations at Regional Scale and Their Implications for Pollution Mitigation

Indoor PM_2.5, particulate matter no more than 2.5 μm in aerodynamic equivalent diameter, has very high spatiotemporal variabilities; and exploring the key factors influencing the variabilities is critical for purifying air and protecting human health. Here, we conducted a longer-term field monitoring campaign using low-cost sensors and evaluated inter- and intra-household PM_2.5 variations in rural areas where energy or stove stacking is common. Household PM_2.5 varied largely across different homes but also within households. Using generalized linear models and dominance analysis, we estimated that outdoor PM_2.5 explained 19% of the intrahousehold variation in indoor daily PM_2.5, whereas factors like the outdoor temperature and indoor-outdoor temperature difference that was associated with energy use directly or indirectly, explained 26% of the temporal variation. Inter-household variation was lower than intrahousehold variation. The inter-household variation was strongly associated with distinct internal sources, with energy-use-associated factors explaining 35% of the variation. The statistical source apportionment model estimated that solid fuel burning for heating contributed an average of 31%-55% of PM_2.5 annually, whereas the contribution of sources originating from the outdoors was ≤10%. By replacing raw biomass or coal with biomass pellets in gasifier burners for heating, indoor PM_2.5 could be significantly reduced and indoor temperature substantially increased, providing thermal comforts in addition to improved air quality.

Synergistic Effect of Reactive Oxygen Species in Photothermocatalytic Removal of VOCs from Cooking Oil Fumes over Pt/CeO2/TiO2

The volatile organic compounds (VOCs) from cooking oil fumes are very complex and do harm to humans and the environment. Herein, we develop the high-efficiency and energy-saving synergistic photothermocatalytic oxidation approach to eliminate the mixture of heptane and hexanal, the representative VOCs with high concentrations in cooking oil fumes. The Pt/CeO₂/TiO₂ catalyst with nanosized Pt particles was prepared by the simple hydrothermal and impregnation methods, and the physicochemical properties of the catalyst were measured using numerous techniques. The Pt/CeO₂/TiO₂ catalyst eliminated the VOC mixture at low light intensity (100 mW cm^-2) and low temperature (200 °C). In addition, it showed 25 h of catalytic stability and water resistance (water concentration up to 20 vol %) at 140 or 190 °C. It is concluded that O₂ picked up the electrons from Pt to generate the ^•O₂^- species, which were transformed to the O₂^2- and O^- species after the rise in temperature. In the presence of water, the ^•OH species induced by light irradiation on the catalyst surface and the ^•OOH species formed via the thermal reaction were both supplementary oxygen species for VOC oxidation. The synergistic interaction of photo- and thermocatalysis was generated by the reactive oxygen species.

The psychological status mediates the effect of indoor air pollution on recurrent spontaneous abortion

BACKGROUND

Indoor air pollution (IAP) exposure and psychological status have been recognized as important risk factors for adverse pregnancy outcomes, but their mediating effects on recurrent spontaneous abortion (RSA) have not been analyzed. Therefore, the purpose of this study is to explore the association between IAP and RSA and to examine the mediating effect of psychological status on their association.

METHODS

This study included 830 RSA cases and 2156 controls in Gansu province, China. The Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) questionnaires were used to collect information on participants' psychological status. The IAP exposure was collected by the survey on cooking fuel use, kitchen ventilation characteristics, cooking styles, and indoor smoking, etc. Multivariable logistic regression was used to examine the associations between IAP exposure and RSA. The mediation analysis was used to evaluate the mediation effects of IAP and psychological status on RSA while controlling for confounding.

RESULTS

Among these cases, 16.87% cooked with unclean cooking fuel (UCF) and 37.00% lacked cooking ventilation, which was much higher than the controls. Active smoking and the use of UCF were associated with RSA, with an odds ratio (OR) of 3.374 [95% confidence interval (CI): 1.510-7.541] and 1.822 (95% CI: 1.328-2.500), respectively. We found that the use of a range hood was a protective factor for RSA, with an OR of 0.590 (95% CI: 0.463-0.752). There was a significant mediation effect of depression on the association between IAP and RSA, which accounted for 5.61%-9.22% of the total effect of IAP on RSA.

CONCLUSION

The IAP may be an important risk factor for RSA, which may be intensified by the poor psychological status, and the use of ventilation equipment when cooking is a protective factor for RSA.

The Effect of Kitchen Ventilation Modification on Independent and Combined Associations of Cooking Fuel Type and Cooking Duration with Suicidal Ideation: A Cross-Sectional Study

Although household air pollution (HAP) is associated with an increased risk of mental disorders, evidence remains scarce for the relationship between HAP and suicidal ideation. A total of 21,381 qualified participants were enrolled on the Henan Rural Cohort Study. HAP information including cooking fuel type, cooking duration and kitchen ventilation was collected by questionnaires. Suicidal ideation was evaluated by item nine of the Patient Health Questionnaire-9 (PHQ-9). Independent and combined associations of cooking fuel type and cooking duration with suicidal ideation were explored by logistic regression models. Analyses were conducted in different kitchen ventilation groups to detect the potential effect modification. The adjusted odds ratio (OR) and 95% confidence interval (95% CI) of solid fuel users versus clean fuel users for suicidal ideation was 1.37 (1.16, 1.62), and the risk of suicidal ideation increased by 15% (95% CI: 5%, 26%) for each additional hour of the cooking duration. Participants cooking with solid fuel for long durations were related to the highest risk of suicidal ideation (OR (95% CI): 1.51 (1.22, 1.87)). However, all these associations were not observed in those cooking with mechanical ventilation. Mechanical ventilation ameliorated relationships between solid fuel use and long-duration cooking with suicidal ideation.

Characteristics of PM2.5 emissions from six types of commercial cooking in Chinese cities and their health effects

Commercial kitchens may pose significant health risks to workers because they generate large quantities of fine particulate matter (PM_2.5). In our study, the concentrations and emission rates of PM_2.5 in cooking environments were measured for six types of commercial kitchens that used electricity and natural gas (including traditional Chinese kitchens, western kitchens, teppanyaki kitchens, fried chicken kitchens, barbecue kitchens, and hotpot cooking area). Furthermore, a preliminary health risk assessment of the chefs was undertaken using the annual PM_2.5 inhalation and PM_2.5 deposition rates into the upper airways and tracheobronchial and alveolar regions of the human body. Results showed that cooking in the teppanyaki kitchen generated the highest amount of PM_2.5, with a mean emission rate of 7.7 mg/min and a mean mass concentration of 850.4 ± 533.4 μg/m³ in the breathing zone. Therefore, teppanyaki kitchens pose highest PM_2.5 exposure risks to chefs, with the highest rate of PM_2.5 deposition in the upper airways (6.38 × 10⁵ μg/year), followed by Chinese kitchens. The PM_2.5 concentrations and emission rates of each kitchen varied greatly with the dishes cooked. The mean PM_2.5 concentration was the highest during Chinese stir-frying, with the peak concentration reaching more than 20,000 μg/m³, followed by pan-frying, deep-frying, stewing, and boiling. A rise in PM_2.5 concentration was also observed during the start of stir-frying and in the middle to late stages of pan-frying and grilling meat. The results obtained in our study may contribute in understanding the characteristics of PM_2.5 emissions from various types of commercial kitchens and their health effects.

Reactive Chlorine Emissions from Cleaning and Reactive Nitrogen Chemistry in an Indoor Athletic Facility

Indoor gas-phase radical sources are poorly understood but expected to be much different from outdoors. Several potential radical sources were measured in a windowless, light-emitting diode (LED)-lit room in a college athletic facility over a 2 week period. Alternating measurements between the room air and the supply air of the heating, ventilation, and air-conditioning system allowed an assessment of sources. Use of a chlorine-based cleaner was a source of several photolabile reactive chlorine compounds, including ClNO₂ and Cl₂. During cleaning events, photolysis rates for these two compounds were up to 0.0023 pptv min^-1, acting as a source of chlorine atoms even in this low-light indoor environment. Unrelated to cleaning events, elevated ClNO₂ was often observed during daytime and lost to ventilation. The nitrate radical (NO₃), which is rapidly photolyzed outdoors during daytime, may persist in low-light indoor environments. With negligible photolysis, loss rates of NO₃ indoors were dominated by bimolecular reactions. At times with high NO₂ and O₃ ventilated from outdoors, N₂O₅ was observed. Elevated ClNO₂ measured concurrently suggests the formation through heterogeneous reactions, acting as an additional source of reactive chlorine within the athletic facility and outdoors.

Deaths Attributable to Indoor PM2.5 in Urban China When Outdoor Air Meets 2021 WHO Air Quality Guidelines

The World Health Organization reduced the recommended level of annual mean PM_2.5 concentrations to 5 μg/m³ in 2021. Previously, the guideline was geared toward ambient air pollution, and now it explicitly applies to indoor air pollution. However, the disease burden attributed to different indoor emission sources has been overlooked, particularly in urban areas. Our objective was to estimate the mortality attributable to indoor PM_2.5 in urban areas in China. Our model estimated 711 thousand (584-823) deaths and 2.75 trillion (2.26-3.19) CNY economic losses attributable to PM_2.5 in urban China in 2019, in which indoor sources contributed 394 thousand (323-457) deaths and 1.53 trillion (1.25-1.77) CNY losses. There would still be 536 thousand (427-638) PM_2.5-attributable deaths and 2.07 trillion (1.65-2.47) CNY losses each year when the outdoor PM_2.5 is 5 μg/m³, of which 485 thousand (386-578) deaths and 1.87 trillion (1.49-2.23) CNY are attributable to indoor sources. Despite cleaner outdoor air and no solid fuels being used, considerable health hazards and economic losses are attributable to indoor PM_2.5. Measures to reduce PM_2.5 exposure in humans from both indoor and outdoor sources are required to achieve a substantial reduction in deaths.

Carbonyls from commercial, canteen and residential cooking activities as crucial components of VOC emissions in China

Cooking in China supply the large population with nutrition and, as a commercial activity, it also promotes the economic growth of Chinese society. The specific cooking styles in China can produce complex volatile organic compound (VOC) emissions. The resulting adverse effects on the environment and human health of carbonyls from cooking should not be ignored. We quantitatively evaluated the contribution of carbonyls to common VOCs (carbonyl/VOC ratio) from cooking activities in China through the establishment and comparison of the source profiles, emission factors (EFs), emission amount and ozone formation potential (OFP). It was found that carbonyls are crucial components of VOCs from commercial, canteen and residential cooking activities (COC, CAC and REC, respectively). The carbonyl/VOC ratio from cooking activities in China had EFs, emissions, and a total OFP of 22-65 %, 23-34 %, and 49-104 %, respectively. The high OFP was due to the high OFP emissions intensity (OFP_EI) and maximum incremental reactivity (MIR) values of carbonyls. This indicates that to alleviate O₃ pollution, OFP-based control measures that target carbonyls might be more efficient than measures that target common VOCs. Priority should be given to emission controlling COC emissions, specifically those from medium- and large-scale catering. Formaldehyde, acetaldehyde, and hexanal were the key carbonyl species that form O₃ in the environment. Our findings imply that cooking-emitted carbonyls should not be overlooked in investigations of O₃ formation and that these compounds should be subject to strict regulations.

A review of critical residential buildings parameters and activities when investigating indoor air quality and pollutants

Indoor air in residential dwellings can contain a variety of chemicals, sometimes present at concentrations or in combinations which can have a negative impact on human health. Indoor Air Quality (IAQ) surveys are often required to characterize human exposure or to investigate IAQ concerns and complaints. Such surveys should include sufficient contextual information to elucidate sources, pathways, and the magnitude of exposures. The aim of this review was to investigate and describe the parameters that affect IAQ in residential dwellings: building location, layout, and ventilation, finishing materials, occupant activities, and occupant demography. About 180 peer-reviewed articles, published from 01/2013 to 09/2021 (plus some important earlier publications), were reviewed. The importance of the building parameters largely depends on the study objectives and whether the focus is on a specific pollutant or to assess health risk. When considering classical pollutants such as particulate matter (PM) or volatile organic compounds (VOCs), the building parameters can have a significant impact on IAQ, and detailed information of these parameters needs to be reported in each study. Research gaps and suggestions for the future studies together with recommendation of where measurements should be done are also provided.

Physical activity attenuates the association between household air pollution and health-related quality of life in Chinese rural population: the Henan Rural Cohort Study

BACKGROUND AND PURPOSE

Limited research focused on the association between household air pollution (HAP) and health-related quality of life (HRQoL). This study aimed to investigate the association of HAP with HRQoL and the effect modification of physical activity.

METHOD

A total of 16,761 eligible participants were derived from the Henan Rural Cohort Study. Based on structured questionnaires, HAP was assessed by fuel type, cooking duration and kitchen ventilation; HRQoL was measured with utility index and VAS score from the European Quality of Life Five Dimension Five Level Scale (EQ-5D-5L); physical activity was assessed by the International Physical Activity Questionnaire. Generalized linear models and tobit regression models were utilized to explore the relationship of HAP with HRQoL. Further sensitivity analyses were conducted using structural equation models.

RESULTS

Compared with those who cooked with clean fuels, short-duration, or good kitchen ventilation, participants who cooked with solid fuels, long-duration, and poor ventilation had lower utility index and VAS score (All P < 0.001). The decrease in utility index for solid fuel users vs. clean fuel users were 0.06 [95%confidence interval (CI) 003, 0.08], 0.03 (95%CI 0.01, 0.04) and 0.02 (95%CI 0.01, 0.04) in low, moderate and high physical activity group, respectively, which decreased with physical activity levels (Pfor interaction < 0.05). Similar results were observed in associations of kitchen ventilation with utility index and VAS score.

CONCLUSION

HAP negatively associated with HRQoL in rural population, and potential intervention aimed at maintaining adequate physical activity.

TRAIL REGISTRATION

The Henan Rural Cohort Study has been registered at Chinese Clinical Trial Register (Registration number: ChiCTR-OOC-15006699). Date of registration: 06 July, 2015. http://www.chictr.org.cn/showproj.aspx?proj=11375 .

Outdoor air pollution enhanced the association between indoor air pollution exposure and hypertension in rural areas of eastern China

Recently, the high prevalence of hypertension (HTN) has caused serious disease burden. Previous studies mostly focused on the separate association between outdoor or indoor air pollution and HTN, and did not explore their possible interaction with HTN. To explore this issue, this study investigated the relationship between indoor and outdoor air pollution and HTN and their possible interactions among adult residents in 14 rural areas in eastern China. The generalized linear model (GLM) and interplot model were used to evaluate the separate effects and potential interaction of outdoor or indoor air pollutants on HTN. In separate analyses, we found a significant positive association between outdoor and indoor air pollution and HTN, and a significant negative association between range hood use and HTN. In the interaction analysis, outdoor air pollution could significantly enhance the positive effects of indoor air pollution on HTN. In addition, PM_2.5 and O₃ could significantly reduce the protective effect of range hoods use on HTN. Finally, we found that females were more susceptible to both indoor and outdoor air pollution.

Maternal exposure to cooking oil fumes during pregnancy and autistic-like behaviors in Chinese preschoolers

There is growing evidence that cooking oil fumes (COFs) are harmful indoor air pollutants. However, there is a dearth of research investigating whether maternal COFs exposure during pregnancy may affect children's autistic-like behaviors in China. This study aimed to explore this association, and examine the effects of different cooking fuels and ventilation methods used by mothers on the presence of autistic-like behaviors. This study analyzed the survey data of the Longhua Child Cohort Study in 2017 with a total of 62,372 mothers enrolled in this study. A self-administrative questionnaire was used to collect information on socio-demographic characteristics, cooking habits during pregnancy, and autistic-like behaviors (measured using the Autism Behavior Checklist). After adjusting for potential confounders, the results showed that compared with children whose mothers never cooked during pregnancy, children whose mothers cooked sometimes, often, always during pregnancy had the higher risk of autistic-like behaviors. As the amounts of COFs exposed to and the frequency of cooking during pregnancy increased, the risk of a child's autistic-like behaviors also increased. Mothers using natural gas as cooking fuels had a lower risk of their child having autistic-like behaviors, compared with mothers using coal or other cooking fuels. Furthermore, pregnant women using ventilation measures during cooking significantly decreased likelihood of the presence of autistic-like behaviors in their children. These results suggest that maternal exposure to COFs during pregnancy may increase the likelihood of the presence of autistic-like behaviors in offspring. These findings support a recommendation that pregnant women should avoid exposure to COFs and use clean fuels and ventilation equipment in kitchens to reduce the risk of autistic-like behaviors in children.

High time-resolution measurements of ultrafine and fine woodsmoke aerosol number and surface area concentrations in biomass burning kitchens: A case study in Western Kenya

Indoor air pollution associated with biomass combustion for cooking remains a significant environmental health challenge in rural regions of sub-Saharan Africa; however, routine monitoring of woodsmoke aerosol concentrations continues to remain sparse. There is a paucity of field data on concentrations of combustion-generated ultrafine particles, which efficiently deposit in the human respiratory system, in such environments. Field measurements of ultrafine and fine woodsmoke aerosol (diameter range: 10-2500 nm) with field-portable diffusion chargers were conducted across nine wood-burning kitchens in Nandi County, Kenya. High time-resolution measurements (1 Hz) revealed that indoor particle number (PN) and particle surface area (PSA) concentrations of ultrafine and fine woodsmoke aerosol are strongly temporally variant, reach exceedingly high levels (PN > 10⁶ /cm³ ; PSA > 10⁴  μm² /cm³ ) that are seldom observed in non-biomass burning environments, are influenced by kitchen architectural features, and are moderately to poorly correlated with carbon monoxide concentrations. In five kitchens, PN concentrations remained above 10⁵ /cm³ for more than half of the day due to frequent cooking episodes. Indoor/outdoor ratios of PN and PSA concentrations were greater than 10 in most kitchens and exceeded 100 in several kitchens. Notably, the use of metal chimneys significantly reduced indoor PN and PSA concentrations.

In vitro and in vivo low-dose exposure of simulated cooking oil fumes to assess adverse biological effects

Cooking oil fumes (COFs) represent a major indoor environmental pollutant and exhibit potent mutagenic or carcinogenic health effects caused by containing various heterocyclic aromatic amines (HAAs) and long-chain aldehydes. Despite some evaluation of the cumulative exposure of COFs to cancer cells under high concentration were evaluated, their biological adverse effects with low-dose exposure to healthy cells had been inadequately investigated. Herein, we firstly scrutinized the three selected typically toxic compounds of heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 3,8-dimethylammidazo[4,5-f]quinoxalin-2-amine (MeIQx) and trans, trans-2,4-decadienal (TDA)) emitted from COFs. In vitro studies revealed that the PhIP, MeIQx and TDA aerosol particles were negligible toxicity to cancer cells (A549 and HepG-2) but strong cytotoxicity to normal healthy cells (HelF and L02) under 0.5–4 μg/mL low dose exposure based on the reactive oxygen species (ROS) mechanism. In vivo studies demonstrated that PhIP caused significant lung and liver damage after exposure to PhIP for 30 days with mice. These results indicated the direct proof of healthy cell damage even at low-dose exposure to HAAs and aldehydes.

Emission characteristics of formaldehyde from natural gas combustion and effects of hood exhaust in Chinese kitchens

Formaldehyde (HCHO) is a well known carcinogen. While most studies investigate emission from wood-based materials, knowledge about releasing of HCHO by natural gas combustion is quite limited. This study conducted field measurements in 9 households to address this issue. We found that emission factor is mainly in the range of 50-200 mg_HCHO/m³_natural gas (median value is 85 mg/m³). Emission rate mainly falls into a range of 0.1-0.4 mg_HCHO/min (median value is 0.16 mg/min). It is also revealed that as the natural gas flow rate increases, the emission factor decreases with a statistically significant Spearman correlation coefficient of -0.46 (p < 0.05). The emission rate shows an opposite trend with a Spearman correlation coefficient of 0.48 (p < 0.05). Formaldehyde generated by natural gas combustion in kitchens can quickly disperse to an adjacent living room when kitchen door is open. A range hood can effectively remove formaldehyde in kitchens if kitchen window is open and kitchen door is closed. Its performance would decrease by half otherwise. These results imply a health co-benefit of reducing household usage of carbon-based natural gas in the age of carbon neutrality aiming climate change.

Assessment of Kitchen Air Pollution: Health Implications for the Residents of Ilorin South, Nigeria

Indoor air quality is essential, so its quality cannot be compromised. Hence, this research assessed indoor gaseous air pollutant concentrations from sources in thirty-three residential kitchens within the 4-zone of Ilorin-South Local Government, Kwara, Nigeria. The work focused on SO2, NO2, and CO emission concentration quantification, determination of the air quality index (AQI), estimation of health assessment risk, and deduced their health implications on the residents. The concentrations of NO2 and SO2 were determined by the Saltzman method using a Gilair-3 air sampler, while the concentration of CO was determined using an MSA Altair-5x multigas detector. Three types of eleven kitchen environments each (kitchens where liquefied petroleum gas (LPG), charcoal, and firewood were used as fuel sources) were considered. The concentrations of NO2, SO2, and CO were higher in kitchens that used charcoal and firewood. The major health risks were deduced in percentages from the questionnaire administered, where headaches had the highest percentage (20.7). The model indicated that the concentrations of the pollutants in the evening, irrespective of the sampling points, were higher than those in the morning. Firewood contributed significantly more than charcoal and LPG (p < 0.05). The results of the health assessment risk showed that the risk estimated for normal exposure to the pollutants in all the households studied revealed a hazard quotient of <1.0 except for SO2 from firewood for infants and children = 1.09. The AQI results showed the worst health conditions for households that used firewood (0.103-4.760 ppm NO2; 0.327-0.647 ppm SO2; and 12.30-57.83 ppm CO). The study concluded that the use of LPG should be preferred as a source of fuel for cooking.

Household cooking oil type and risk of oral micronucleus frequency in Chinese nonsmokers

Household animal fat has been linked to increased incidence of cancers compared with vegetable fat. However, few epidemiological studies have associated these two cooking oil types with precancerous genotoxic effects, such as occurrence of micronuclei (MN). This study aimed to explore the association between oral MN frequency and household cooking oil type and whether the association can be attributed to polycyclic aromatic hydrocarbons (PAHs). We collected information about individual cooking oil use, measured genotoxic effects by MN tests and urinary PAHs metabolites (OHPAHs) in 245 nonsmokers. The associations between household cooking oil type and MN frequency and OHPAHs were analyzed using generalized linear models (GLMs) and logistic regression models, evaluating odds ratios and coefficient (95% confidence intervals) (ORs, 95% Cls; β, 95% Cls). The odds of animal fat consumers, rather than vegetable fat consumers, was positively associated with higher MN frequency (OR = 1.94, P < 0.05). The associations were discovered in participants only using kitchen ventilation (OR = 2.04, P < 0.05). Animal fat consumers had higher total OHPAHs than vegetable fat consumers (1.58 ± 0.22 mg/mol, Cr vs 1.20 ± 0.12 mg/mol, Cr; P = 0.028). Significant correlations were observed between total OHPAHs quartiles and increased MN frequency (β = 0.38, P-trend = 0.026). After stratifying by household cooking oil type, sensitivity analyses showed that the positive association between total OHPAHs quartiles and increased MN frequency was only observed in animal fat consumers (β = 0.61, P-trend = 0.030). In conclusion, usage of household animal fat was associated with an increased odds of oral MN frequency in Chinese nonsmokers and the odds correlated with increased PAHs exposure. This finding supplemented evidence associating cooking oil type with genotoxic effects and explained its association with PAHs exposure.

α-Fe2O3 nanoparticles and hazardous air pollutants release during cooking using cast iron wok in a commercial Chinese restaurant

Long-term exposure to fine particles (PM_2.5), ultrafine particles (UFPs), and volatile organic compounds (VOCs) emissions from cooking has been linked to adverse human health effects. Here, we measured the real-time number size distribution of particles emitted when cooking two served food in Chinese restaurants and estimated the emission rate of UFPs and PM_2.5. Experiments were conducted under a control hood, and both online measurement and offline analysis of PM_2.5 were carried out. The measured emission rates of PM_2.5 generated from deep-frying and grilling were 0.68 ± 0.11 mg/min and 1.58 ± 0.25 mg/min, respectively. Moreover, the UFPs emission rate of deep-frying (4.3 × 10⁹ #/min) is three times higher than that of grilling (1.4 × 10⁹ #/min). Additionally, the PM_2.5 emission of deep-frying was comprised of a considerable amount of α-Fe₂O₃ (5.7% of PM_2.5 total mass), which is more toxic than other iron oxide species. A total of six carcinogenic HAPs were detected, among which formaldehyde, acrolein, and acetaldehyde were found to exceed the inhalation reference concentration (RfC) for both cooking methods. These findings can contribute to future evaluation of single particle and HAPs emission from cooking to better support toxicity assessment.

A comprehensive study of volatile organic compounds from the actual emission of Chinese cooking

China's current perspective for big cities was filled with great population, great number of restaurants, growing gaseous pollutants, and great pollution. Volatile organic compounds (VOCs) were the main components of catering industry gaseous pollutants. In this study, we collected and analyzed VOCs from home cooking (HC), Sichuan and Hunan cuisine (S&H), Shandong cuisine (SD), Anhui cuisine (AH), Beijing cuisine (BJ), and barbecue (BBQ). The result showed that BBQ gave the highest VOC concentration (6287.61 μg m^-3), followed by HC (1806.11 ± 2401.85 μg m^-3), SD (2238.55 ± 2413.53 μg m^-3), AH (1745.89 μg m^-3), S&H (1373.58 ± 1457.45 μg m^-3), and BJ (288.81 μg m^-3). The abundance of alkane was higher among BBQ, Anhui cuisine, and HC with the proportion from 33 to 71%. SD contained higher halohydrocarbons proportion (33%). BJ was characterized by high-oxygenated volatile organic compounds proportion (50%). The ozone formation potential (OFP) of BBQ was much greater than other cuisines. The degree of stench pollution from cooking VOCs of HC was 17.51 ± 16.95, followed by S&H (15.77 ± 16.85), SD (15.12 ± 14.17), AH (16.29), BBQ (2.58), and BJ (1.81). Benzene had the highest life cancer risk (LCR) in SD (2.11×10^-5 ± 3.12×10^-5), following HC (4.50×10^-6 ± 3.83×10^-6) and S&H (4.08×10^-6 ± 4.49×10^-6). Acrolein had a high hazard index (HI) in HC (789.81 ± 768.77), following AH (728.78), S&H (689.89 ± 776.07), SD (664.29 ± 648.77), BBQ (65.93), and BJ (62.84).

Occupant behavior and indoor particulate concentrations in daycare centers

'Occupant behavior' is the primary mechanism determining indoor particulate concentrations. Various indoor human activities generate particulate matter. Human-building interactions, such as window opening behavior, change the number of outdoor particulate matter introduces to the building. 'Daycare center' where young children spend considerable time has an occupant schedule distinguished from other types of buildings. In the study, we analyzed the effects of occupant behavior on indoor particle concentrations in daycare centers by on-site monitoring. The measurements were performed in four daycare centers located in Gyeonggi-do, South Korea. Optical particle counters(OPS, model 3330, TSI Inc., Shoreview, MN, USA) were used for particulate concentration monitoring. The source strengths of particles resuspended by each human activity were calculated, and their contributions to indoor particle concentrations were evaluated. Further, characteristics of human-building interactions and their corresponding impacts on indoor air quality were also analyzed. Results showed that particle resuspension was greater when occupants were awake (mean, 41.0 particles·min^-1) than when they were asleep (mean, 9.2 particles·min^-1), and the contribution of occupant status was also higher when awake (37-70% vs. 8-18%) for particles sized (0.3-10.0 μm). Analyzing five detailed human activities, vacuuming (9.8·10⁷ particles·min^-1) emitted the highest amount of particulate matter per person, followed by physical activity (4.8·10⁷ particles·min^-1), sedentary activity (1.9·10⁷ particles· min^-1), meals (1.9·10⁷ particles·min^-1), and nap time (8.1·10⁶ particles·min^-1). The study suggests that vacuuming should be avoided while children are occupied. This research also shows that children could be exposed to high daily average indoor particulate concentration (up to 1217 particles·cm^-3) when windows were opened for an extended period of time while poor outdoor air quality. These results indicate that indoor air quality can be severely degraded by opening windows without considering the level of outdoor particle concentration.

Study on the Influence of Fresh Air System of Range Hood on Kitchen Air Quality

In this paper, a combination of simulation and testing is used to quantitatively analyze the influence of a fresh air system of indoor range hood on kitchen air quality. The evaluation criteria of kitchen air quality are established based on the air age and air exchange efficiency. The results show that, when the fresh air system is switched to on from off, the indoor mean air age is reduced to 94.7 s from 468.6 s, and the air exchange efficiency is improved to 82.4% from 16.7%. The air quality is upgraded to fresh from moderate pollution. The presented simulation analysis process can provide a guideline for in-depth study of the kitchen air quality and quantitatively assess the kitchen fresh air system.

In-kitchen aerosol exposure in twelve cities across the globe

Poor ventilation and polluting cooking fuels in low-income homes cause high exposure, yet relevant global studies are limited. We assessed exposure to in-kitchen particulate matter (PM_2.5 and PM₁₀) employing similar instrumentation in 60 low-income homes across 12 cities: Dhaka (Bangladesh); Chennai (India); Nanjing (China); Medellín (Colombia); São Paulo (Brazil); Cairo (Egypt); Sulaymaniyah (Iraq); Addis Ababa (Ethiopia); Akure (Nigeria); Blantyre (Malawi); Dar-es-Salaam (Tanzania) and Nairobi (Kenya). Exposure profiles of kitchen occupants showed that fuel, kitchen volume, cooking type and ventilation were the most prominent factors affecting in-kitchen exposure. Different cuisines resulted in varying cooking durations and disproportional exposures. Occupants in Dhaka, Nanjing, Dar-es-Salaam and Nairobi spent > 40% of their cooking time frying (the highest particle emitting cooking activity) compared with ∼ 68% of time spent boiling/stewing in Cairo, Sulaymaniyah and Akure. The highest average PM_2.5 (PM₁₀) concentrations were in Dhaka 185 ± 48 (220 ± 58) μg m^-3 owing to small kitchen volume, extensive frying and prolonged cooking compared with the lowest in Medellín 10 ± 3 (14 ± 2) μg m^-3. Dual ventilation (mechanical and natural) in Chennai, Cairo and Sulaymaniyah reduced average in-kitchen PM_2.5 and PM₁₀ by 2.3- and 1.8-times compared with natural ventilation (open doors) in Addis Ababa, Dar-es-Salam and Nairobi. Using charcoal during cooking (Addis Ababa, Blantyre and Nairobi) increased PM_2.5 levels by 1.3- and 3.1-times compared with using natural gas (Nanjing, Medellin and Cairo) and LPG (Chennai, Sao Paulo and Sulaymaniyah), respectively. Smaller-volume kitchens (<15 m³; Dhaka and Nanjing) increased cooking exposure compared with their larger-volume counterparts (Medellin, Cairo and Sulaymaniyah). Potential exposure doses were highest for Asian, followed by African, Middle-eastern and South American homes. We recommend increased cooking exhaust extraction, cleaner fuels, awareness on improved cooking practices and minimising passive occupancy in kitchens to mitigate harmful cooking emissions.

Indoor sources strongly contribute to exposure of Chinese urban residents to PM2.5 and NO2

Ambient fine particulate matter (diameters <2.5 µm; PM_2.5) and nitrogen dioxide (NO₂) pollution are responsible for substantial health burdens in China, contributing to a considerable proportion of global mortality. Simultaneously, the proportion of indoor smoking and cooking-induced PM_2.5 and NO₂ pollution lacks robust exposure assessment findings. Rapid poverty alleviation and urbanization affect the proportion of indoor vs outdoor sources of PM_2.5 and NO₂ exposures in China. The current understanding of air pollution and health lacks an understanding of source-specific air pollution exposure. Thus, we developed a model to estimate human exposure to pollutants originating indoors and outdoors. We found indoor sources strongly contribute to total PM_2.5 and NO₂ exposure in urban China and are comparable to outdoor sources. Cooking contributes 28.6 μg m^-3 PM_2.5 and 10.8 μg m^-3 NO₂ on average to the air people breathe, and so did smoking contributing 14.2 μg m^-3 PM_2.5 and 0.6 μg m^-3 NO₂, respectively. The results give us a clearer understanding of exposure to PM_2.5 and NO₂ from indoor and outdoor sources. Pollutant control policies on ambient exposure levels without addressing indoor air pollution in China are insufficient given our estimated exposure levels.

Assessing Impacts of Additives on Particulate Matter and Volatile Organic Compounds Produced from the Grilling of Meat

Cooking fumes are an important source of volatile organic compounds (VOCs), particulate matter (PM), and carbonyl compounds. The additive is wildly applied in grilling meat for flavor improvement. However, the effects of additives on cooking fumes emissions, such as volatile organic compounds (VOCs), particulate matter (PM), and carbonyl compounds, in meat grilling have not been studied. The impact of four additives, including white pepper, salt, garlic powder, and compound marinade, on the emission characteristics of cooking fumes from the grilling meat was investigated. The concentrations of VOCs and carbonyl compounds in the cooking fumes were analyzed by TD-GC/MS and HPLC, respectively. The PM emission characteristics (mass concentration and size distribution) were measured by DustTrak DRX aerosol monitor in real-time. Results showed that the application of white pepper, salt, garlic powder, and mixed spices could significantly reduce the total particles mass concentration (TPM) emissions during meat-grilling by 65.07%, 47.86%, 32.87%, and 56.01%, respectively. The mass concentration of PM during meat-grilling reached maximum values ranging from 350 to 390 s and gradually fell at the final stages of grilling. The total concentration of 22 representative VOCs emitted from the grilling was significantly increased in grilling meat marinated with compound additives. Aromatic hydrocarbons were the predominant VOCs species, followed by ketone compounds. During the grilling process, formaldehyde, acetaldehyde, propionaldehyde, and acetone were major carbonyl compounds. The low molecular weight carbonyl compounds (C1–C3) in cooking fumes were dominant carbonyl compounds.

Emission of BTEX compounds from the frying process: Quantification, environmental effects, and probabilistic health risk assessment

Frying is one of the cooking methods which generates mono aromatic hydrocarbons, including benzene, toluene, ethylbenzene, and xylene (BTEX); subsequently, it affects health through carcinogenic (CR) and non-carcinogenic risks (n-CR). However, their environmental effects known by secondary organic aerosols (SOA) and ozone formation potential (OFP) were also attended by many scientists. Therefore, this study quantified the BTEX emissions from 4 types of most commonly used edible oils (canola, corn, sunflower, and blend) under various frying conditions of temperatures and food additives. Furthermore, the effects of the chemicals in the light of health (CR and n-CR) and environment (SOA and OFP) were also investigated. The study results showed that higher temperatures could significantly increase the emissions, while the addition of food ingredients significantly reduces the emissions. The rank order of emitted chemical was obtained as T > B > E > X. The blend had the most emission among oils, followed by, in descending order, corn, sunflower, and canola. In association with environmental effects, the orders of X > T > E > B and T ∼ E > X > B were obtained for OFP and SOA, respectively. THQ for blend, corn, canola, and sunflower oils was higher than 1 (1.76, 1.35, 1.27, and 1.002, respectively), showing a considerable n-CR when the hood was off. In this respect, TCR for the oils (1.78 × 10^-4, 1.45 × 10^-4, 1.39 × 10^-4, and 1.05 × 10^-4, respectively) shown the probable risk for all oils. Moreover, hood switching reduced the risk by about 11-81%.

Characterization of cooking-related ultrafine particles in a US residence and impacts of various intervention strategies

Interventions that improve air exchange or filter the air have the potential to reduce particle exposures from residential cooking. In this study, we evaluated the effect of using a range hood, opening kitchen windows, and using portable air cleaners (PACs) in various home locations on the concentrations of ultrafine particles (UFPs) at different times and in different rooms during and after cooking. All experiments were conducted using a standardized cooking protocol in a real-world naturally-ventilated apartment located in the northwest United States. Real-time UFP measurements collected from the kitchen, living room, and bedroom locations were used to estimate parameters of a dynamic model, which included time-varying particle emission rates from cooking and particle decay. We found that 1-min mean UFP number concentrations in the kitchen and living room mostly peaked within 0-10 min after cooking ended at levels of 150,000-500,000 particles/cm3. In contrast, the bedroom UFP concentrations were consistently low except for the window-open scenario. While varying considerably with time, the 1-min UFP emission rates were comparable during and within 5-min after cooking, with means (standard deviations) of 0.8 (1.1) × 1012 and 1.1 (1.2) × 1012 particles/min, respectively. Compared with the no-intervention scenario, keeping the kitchen windows open and using a kitchen range hood reduced the mean indoor average UFP concentrations during and 1 h after cooking by ~70% and ~35%, respectively. Along with the range hood on, utilizing a PAC in the kitchen during and after cooking further reduced the mean indoor average UFP levels during and 1 h after cooking by an additional 53%. In contrast, placing the PAC in the living room or bedroom resulted in worse efficacy, with additional 2-13% reductions. These findings provide useful information on how to reduce cooking-related UFP exposure via readily accessible intervention strategies.

Aerosol dynamics modeling of sub-500 nm particles during the HOMEChem study

We spend most of our time in built environments. The cumulative exposure to particulate matter (PM) occurring in these built environments can potentially be comparable to or even exceed that occurring outdoors. Therefore, it is critical to understand the sources, dynamics, and fate of PM in built environments. This work focuses on aerosol dynamics modeling (including coagulation, deposition, and exfiltration) of sub-500 nm particles measured inside a test house during the HOMEChem campaign while performing prescribed cooking activities. Deposition characteristics of the test house, emission rates and factors, and the fate of particles are presented. Number emission rates calculated for two different heat sources (stove and hot plate) and the various meals cooked on them were highest for sub-10 nm particles. Coagulation and deposition contributed comparably to the particle number concentration decay. Most of the PM (90% number-based and 70% mass-based) deposited within the house while the remaining fraction left the test house volume via exfiltration. Simulation results show that while increased air exchange rate reduces indoor PM mass concentration, it can lead to increased number concentration. An increase from 0.5 to 5 ACH (comparable to the equivalent air change rate from running a well-dimensioned portable air cleaner) would result in a 70% reduction in PM mass-based exposure while a further increase from 5 to 20 ACH would only result in an additional 21% reduction.