Assessment of Indoor-Outdoor Particulate Matter Air Pollution: A Review

Every breath you take: High concentration of breathable microplastics in indoor environments

The widespread presence of microplastics (MPs) in the air and their potential impact on human health underscore the pressing need to develop robust methods for quantifying their presence, particularly in the breathable fraction (<5 μm). In this study, Raman micro-spectroscopy (μRaman) was employed to assess the concentration of indoor airborne MPs >1 μm in four indoor environments (a meeting room, a workshop, and two apartments) under different levels of human activity. The indoor airborne MP concentration spanned between 58 and 684 MPs per cubic meter (MP m-3) (median 212 MP m-3, MPs/non-plastic ratio 0-1.6%), depending not only on the type and level of human activity, but also on the surface area and air circulation of the investigated locations. Additionally, we assessed in the same environments the filtration performance of a type IIR surgical facemask, which could overall retain 85.4 ± 3.9% of the MPs. We furthermore estimated a human MP intake from indoor air of 3415 ± 2881 MPs day-1 (mostly poly-amide MPs), which could be decreased to 283 ± 317 MPs day-1 using the surgical facemask. However, for the breathable fraction of MPs (1-5 μm), the efficiency of the surgical mask was reduced to 57.6%.

Multi-Scenario Validation and Assessment of a Particulate Matter Sensor Monitor Optimized by Machine Learning Methods

OBJECTIVE

The aim was to evaluate and optimize the performance of sensor monitors in measuring PM2.5 and PM10 under typical emission scenarios both indoors and outdoors.

METHOD

Parallel measurements and comparisons of PM2.5 and PM10 were carried out between sensor monitors and standard instruments in typical indoor (2 months) and outdoor environments (1 year) in Shanghai, respectively. The optimized validation model was determined by comparing six machining learning models, adjusting for meteorological and related factors. The intra- and inter-device variation, measurement accuracy, and stability of sensor monitors were calculated and compared before and after validation.

RESULTS

Indoor particles were measured in a range of 0.8-370.7 μg/m3 and 1.9-465.2 μg/m3 for PM2.5 and PM10, respectively, while the outdoor ones were in the ranges of 1.0-211.0 μg/m3 and 0.0-493.0 μg/m3, correspondingly. Compared to machine learning models including multivariate linear model (ML), K-nearest neighbor model (KNN), support vector machine model (SVM), decision tree model (DT), and neural network model (MLP), the random forest (RF) model showed the best validation after adjusting for temperature, relative humidity (RH), PM2.5/PM10 ratios, and measurement time lengths (months) for both PM2.5 and PM10, in indoor (R2: 0.97 and 0.91, root-mean-square error (RMSE) of 1.91 μg/m3 and 4.56 μg/m3, respectively) and outdoor environments (R2: 0.90 and 0.80, RMSE of 5.61 μg/m3 and 17.54 μg/m3, respectively), respectively.

CONCLUSIONS

Sensor monitors could provide reliable measurements of PM2.5 and PM10 with high accuracy and acceptable inter and intra-device consistency under typical indoor and outdoor scenarios after validation by RF model. Adjusting for both climate factors and the ratio of PM2.5/PM10 could improve the validation performance.

Digital Surface-Enhanced Raman Spectroscopy-Lateral Flow Test Dipstick: Ultrasensitive, Rapid Virus Quantification in Environmental Dust

This study introduces a novel surface-enhanced Raman spectroscopy (SERS)-based lateral flow test (LFT) dipstick that integrates digital analysis for highly sensitive and rapid viral quantification. The SERS-LFT dipsticks, incorporating gold-silver core-shell nanoparticle probes, enable pixel-based digital analysis of large-area SERS scans. Such an approach enables ultralow-level detection of viruses that readily distinguishes positive signals from background noise at the pixel level. The developed digital SERS-LFTs demonstrate limits of detection (LODs) of 180 fg for SARS-CoV-2 spike protein, 120 fg for nucleocapsid protein, and 7 plaque forming units for intact virus, all within <30 min. Importantly, digital SERS-LFT methods maintain their robustness and their LODs in the presence of indoor dust, thus underscoring their potential for accurate and reliable virus diagnosis and quantification in real-world environmental settings.

Analysing role of airborne particulate matter in abetting SARS-CoV-2 outbreak for scheming regional pandemic regulatory modalities

The mutating SARS-CoV-2 necessitates gauging the role of airborne particulate matter in the COVID-19 outbreak for designing area-specific regulation modalities based on the environmental state-of-affair. To scheme the protocols, the hotspots of air pollutants such as PM2.5, PM10, NH3, NO, NO2, SO2, and and environmental factors including relative humidity (RH), and temperature, along with COVID-19 cases and mortality from January 2020 till December 2020 from 29 different ground monitoring stations spanning Delhi, are mapped. Spearman correlation coefficients show a positive relationship between SARS-COV-2 with particulate matter (PM2.5 with r > 0.36 and PM10 with r > 0.31 and p-value <0·001). Besides, SARS-COV-2 transmission showed a substantial correlation with NH3 (r = 0.41), NO2 (r = 0.36), and NO (r = 0.35) with a p-value <0.001, which is highly indicative of their role in SARS-CoV-2 transmission. These outcomes are associated with the source of PM and its constituent trace elements to understand their overtone with COVID-19. This strongly validates temporal and spatial variation in COVID-19 dependence on air pollutants as well as on environmental factors. Besides, the bottlenecks of missing latent data, monotonous dependence of variables, and the role air pollutants with secondary environmental variables are discussed. The analysis set the foundation for strategizing regional-based modalities considering environmental variables (i.e., pollutant concentration, relative humidity, temperature) as well as urban and transportation planning for efficient control and handling of future public health emergencies.

Validation of an optimised microwave-assisted acid digestion method for trace and ultra-trace elements in indoor PM2.5 by ICP-MS analysis

Three microwave-assisted digestion procedures, followed by analysis of digestates employing inductively coupled mass spectrometry (ICP-MS) were evaluated for use in the determination of elements at trace and ultra-trace levels in PM_2.5 samples. Digestion procedure 1 used 2.5 mL HNO₃ (65%) at 200 °C. Procedure 2, consisted of a two-stage digestion step at 200 °C with 2.5 mL HNO₃ (65%) and 3 μL HF (48%) followed by 24 μL H₃BO₃ (5%). A 10-fold increase in the amounts of HF and H₃BO₃ was used for procedure 3. The addition of HF/H₃BO₃ was carried out to aid the dissolution of silicate matrices and refractory compounds. The digestions were carried out using PTFE ultra-trace inserts which increased the sample throughput threefold. The addition of small quantities of HF resulted in the effective solubilisation of Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Sr, Cd, Sb and Pb. The optimal method using HNO₃/HF/H₃BO₃ digestion as in procedure 3 showed recovery efficiency greater than 70% for all elements. The validated method was applied to quantify the elemental content of indoor and outdoor PM_2.5 (with samples <0.5 mg) at an urban background site in Malta.

The impact of the first United Kingdom COVID-19 lockdown on environmental air pollution, digital display device use and ocular surface disease symptomatology amongst shielding patients

Worldwide lockdown reduced air pollution during the first phase of the COVID-19 pandemic. The relationship between exposure to ambient air pollution, digital display device use and dry eye symptoms amongst patients with severe ocular surface disease (OSD) were considered. Symptoms and air pollutant concentrations for three different time periods (pre, during and post COVID-19 lockdown) were analysed in 35 OSD patients who achieved an immunosuppression risk-stratification score > 3 fulfilling the UK Government criteria for 12-week shielding. OSDI symptoms questionnaire, residential postcode air pollution data obtained from the Defra Automated Urban and Rural monitoring network for concentrations of nitrogen dioxide (NO₂), nitrogen oxides (NOx), particulate matter (PM) with diameters below 10 µm and 2.5 µm, and English Indices of Deprivation were analysed. Significant reductions in NO₂ and NOx concentrations were observed between pre- and during-lockdown periods, followed by a reversal in the post-lockdown period. Changes were linked to the Living Environment outdoor decile. A 12% increase (p = 0.381) in symptomatology during-lockdown was observed that reversed post-lockdown by 19% (p = 0.144). OSDI scores were significantly correlated with hours spent on digital devices (r² = 0.243) but not with air pollutant concentrations. Lockdown measures reduced ambient air pollutants whilst OSD symptomatology persisted. Environmental factors such as increased time indoors and use of bluescreen digital devices may have partly played a role.

Analysis of the Temporal Distribution Characteristics of PM2.5 Concentration and Risk Evaluation of Its Inhalation Exposure

PM_2.5 poses a threat to human health. It is important to evaluate the potential risk of PM_2.5 inhalation exposure when people are located in different spatiotemporal activity locations. In this study, the PM_2.5 concentration was detected by the atmospheric cruise monitoring system (ACMS), a new detection technology used for city-wide PM_2.5 concentration monitoring. People were divided into eight categories of five typical activity patterns, including rest (R), sedentary behavior (SB), light physical activity (LPA), moderate physical activity (MPA), and vigorous physical activity (VPA). The PM_2.5 inhalation exposure risk was then estimated for these typical activities. The research results showed that the time sequence data of the ACMS had a similar tendency to change as those of the traditional air quality monitoring stations (AQMS). Although both passed the stationarity test, the relative error (RE) of the monthly average PM_2.5 concentration between the ACMS and AQMS was 7.5-14%. RE was usually lower when the individual air quality index (IAQI) of PM_2.5 was higher. Otherwise, RE was higher. The research results also showed that PM_2.5 exposure was positively correlated with PM_2.5 concentration, respiration rate, and human activity patterns. Because adults had a higher monthly average potential exposure (MAPE) than minors and that males had a higher MAPE than females. The potential exposure generated by LPA and MPA reached 50.76% of the total potential exposure (TPE). VPA brought about a 14.7% increase in the TPE. The research findings are helpful to understand the temporal distribution characteristics of PM_2.5 concentrations and guide the potential risk evaluation of PM_2.5 inhalation exposure.

Assessing temporal correlation in environmental risk factors to design efficient area-specific COVID-19 regulations: Delhi based case study

Amid ongoing devastation due to Serve-Acute-Respiratory-Coronavirus2 (SARS-CoV-2), the global spatial and temporal variation in the pandemic spread has strongly anticipated the requirement of designing area-specific preventive strategies based on geographic and meteorological state-of-affairs. Epidemiological and regression models have strongly projected particulate matter (PM) as leading environmental-risk factor for the COVID-19 outbreak. Understanding the role of secondary environmental-factors like ammonia (NH₃) and relative humidity (RH), latency of missing data structuring, monotonous correlation remains obstacles to scheme conclusive outcomes. We mapped hotspots of airborne PM_2.5, PM₁₀, NH₃, and RH concentrations, and COVID-19 cases and mortalities for January, 2021-July,2021 from combined data of 17 ground-monitoring stations across Delhi. Spearmen and Pearson coefficient correlation show strong association (p-value < 0.001) of COVID-19 cases and mortalities with PM_2.5 (r > 0.60) and PM₁₀ (r > 0.40), respectively. Interestingly, the COVID-19 spread shows significant dependence on RH (r > 0.5) and NH₃ (r = 0.4), anticipating their potential role in SARS-CoV-2 outbreak. We found systematic lockdown as a successful measure in combatting SARS-CoV-2 outbreak. These outcomes strongly demonstrate regional and temporal differences in COVID-19 severity with environmental-risk factors. The study lays the groundwork for designing and implementing regulatory strategies, and proper urban and transportation planning based on area-specific environmental conditions to control future infectious public health emergencies.

Levels of indoor particulate matter and association with asthma in children in Benin City, Nigeria

The relationship between indoor particulate matter and asthma in children was assessed in this study. Forty-five (45) locations were randomly selected across the five local government areas in Benin City, Edo State, for air quality assessment. Indoor and outdoor particulates (PM_1.0, PM_2.5, and PM₁₀) were monitored monthly using a handheld BLATN particulate sampler (Br-Smart-126S series). Reported clinical cases of asthma in children from 2008 to 2017 were collected from two major hospitals in the metropolis. The data obtained were analysed with SPSS for Windows version 21.0. The average concentrations of indoor and ambient PM ranged between 10.7-26.2 and 19.0-49.4 µg/m³ (PM_1.0), 27.4-59.6 and 45.6-93.0 µg/m³ (PM_2.5), and 33.5-67.9 and 60.9-106.1 µg/m³ (PM₁₀) in the wet and dry seasons. PM_2.5 and PM₁₀ concentrations were observed above the WHO standards. Indoor particulate concentration was significantly (p = 0.001-0.012) higher in the dry season across the locations. Outdoor PM correlated positively (R = 0.568-0.855, p < 0.05; R² = 0.322-0.724, p < 0.001) with their corresponding indoor PM concentration. The hazard ratio (HR) values of PM_2.5 and PM₁₀ exceeded 1 in all the sampling locations during the dry season, while the mean total hazard ratio (THR) of both PM metrics was considerably higher during the dry season than in the wet season. Indoor PM concentrations showed a significant positive correlation with reported cases of asthma (R = 0.498-0.542, p < 0.001) and accounted for 40.6% of the asthma cases during the dry season. The study showed that children in the selected households are at risk of increased asthma exacerbation due to exposure to particulate matter pollution.

Assessment of particulate matter (PM) in ambient air of different settings and its associated health risk in Haripur city, Pakistan

Particulate matter (PM) is a major air pollutant causing serious health problems. The aim of the present study was to find out concentration of PM in ambient air and its associated health risk in Haripur city, Pakistan. Twenty-three samples were taken at various educational institutes, hospitals, recreational areas and industries in Haripur city. Concentration of PM2.5 (µg/m3) and PM10 (µg/m3) was measured with Youngteng YT-HPC 3000A portable PM counter. The results revealed that values of both PM2.5 and PM10 were above the permissible limits (35 µg/m3 for PM2.5 and 150 µg/m3 for PM10) set by Environmental Protection Agency Pakistan (Pak-EPA) in all the educational institutes, hospitals, recreational areas and industries investigated. Furthermore, significant (p<0.05) variation was found in the concentration of both PM2.5 and PM10 in all the educational institutes, hospitals, recreational areas, and industries studied. The concentration of PM2.5 was positively correlated with the concentration of PM10 in all the sampling sites. Therefore, from 1-14 scale standard of health index, the values of PM2.5 and PM10 exhibited that the ambient air quality of Haripur city Pakistan is under high risk. If the regulatory authorities such as Environmental Protection Agency, Health Department and Local Government monitor PM pollution in different settings of Haripur city, then a decrease can be possible in the pollution level. The remedies that can be taken to overcome the problem of ambient air pollution such as PM are plantation of trees at the sites where there are higher levels of air pollutants and use of masks on personal protection basis along with implementation of pollution control system in industries of Hattar Industrial Estate Haripur city, Pakistan.

A Review on Atmospheric Analysis Focusing on Public Health, Environmental Legislation and Chemical Characterization

Atmospheric pollution has been considered one of the most important topics in environmental science once it can be related to the incidence of respiratory diseases, climate change, and others. Knowing the composition of this complex and variable mixture of gases and particulate matter is crucial to understand the damages it causes, help establish limit levels, reduce emissions, and mitigate risks. In this work, the current scenario of the legislation and guideline values for indoor and outdoor atmospheric parameters will be reviewed, focusing on the inorganic and organic compositions of particulate matter and on biomonitoring. Considering the concentration level of the contaminants in air and the physical aspects (meteorological conditions) involved in the dispersion of these contaminants, different approaches for air sampling and analysis have been developed in recent years. Finally, this review presents the importance of data analysis, whose main objective is to transform analytical results into reliable information about the significance of anthropic activities in air pollution and its possible sources. This information is a useful tool to help the government implement actions against atmospheric air pollution.

Susceptibility of individuals with chronic obstructive pulmonary disease to respiratory inflammation associated with short-term exposure to ambient air pollution: A panel study in Beijing

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a leading cause of death worldwide. There is no clear evidence of whether COPD patients are more susceptible to respiratory inflammation associated with short-term exposure to air pollutants than those without COPD.

OBJECTIVES

This study directly compared air pollutant-associated respiratory inflammation between COPD patients and healthy controls.

METHODS

This study is based on the COPDB panel study (COPD in Beijing). Fractional exhaled nitric oxide (FeNO) was repeatedly measured in 53 COPD patients and 82 healthy controls at up to four clinical visits. Concentrations of carbon monoxide (CO), nitrogen monoxide, nitrogen dioxide (NO₂), sulfur dioxide (SO₂), fine particulate matter (PM_2.5), black carbon (BC), ultrafine particles (UFPs), and accumulated-mode particles (Acc) were monitored continuously at a fixed-site monitoring station. Linear mixed-effects models were used to compare the associations between ln-transformed FeNO and average 1-23 h concentrations of air pollutants before the clinical visits.

RESULTS

FeNO was positively associated with interquartile range (IQR) increases in average concentrations of CO, NO₂, SO₂, BC, UFPs, and Acc in all participants, with the strongest associations in different time-windows (range from 6.6% for average 1 h NO₂ exposure to 32.1% for average 7 h SO₂ exposure). Associations between FeNO and average 13-23 h PM_2.5 exposure differed significantly according to COPD status. Increases in FeNO associated with average 1-2 h NO exposure were significant in COPD patients (range 8.9-10.2%), while the associations were nonsignificant in healthy controls. Associations between FeNO and average 1-23 h CO and SO₂ exposure tended to be higher in COPD patients than in healthy controls, although the differences were not significant. UFPs-associated respiratory inflammation was robust in both subgroups.

CONCLUSIONS

COPD patients are more susceptible to respiratory inflammation following PM_2.5, NO, CO, and SO₂ exposure than individuals without COPD.

How Is Indoor Air Quality during Sleep? A Review of Field Studies

This review aimed to provide an overview of the characterisation of indoor air quality (IAQ) during the sleeping period, based only on real life conditions’ studies where, at least, one air pollutant was considered. Despite the consensual complexity of indoor air, when focusing on sleeping environments, the available scientific literature is still scarce and falls to provide a multipollutants’ characterisation of the air breathed during sleep. This review, following PRISMA’s approach, identified a total of 22 studies that provided insights of how IAQ is during the sleeping period in real life conditions. Most of studies focused on carbon dioxide (77%), followed by particles (PM2.5, PM10 and ultrafines) and only 18% of the studies focused on pollutants such as carbon monoxide, volatile organic compounds and formaldehyde. Despite the high heterogeneity between studies (regarding the geographical area, type of surrounding environments, season of the year, type of dwelling, bedrooms’ ventilation, number of occupants), several air pollutants showed exceedances of the limit values established by guidelines or legislation, indicating that an effort should be made in order to minimise human exposure to air pollutants. For instance, when considering the air quality guideline of World Health Organisation of 10 µg·m−3 for PM2.5, 86% of studies that focused this pollutant registered levels above this threshold. Considering that people spend one third of their day sleeping, exposure during this period may have a significant impact on the daily integrated human exposure, due to the higher amount of exposure time, even if this environment is characterised by lower pollutants’ levels. Improving the current knowledge of air pollutants levels during sleep in different settings, as well as in different countries, will allow to improve the accuracy of exposure assessments and will also allow to understand their main drivers and how to tackle them.

Potential of ARIMA-ANN, ARIMA-SVM, DT and CatBoost for Atmospheric PM2.5 Forecasting in Bangladesh

Atmospheric particulate matter (PM) has major threats to global health, especially in urban regions around the world. Dhaka, Narayanganj and Gazipur of Bangladesh are positioned as top ranking polluted metropolitan cities in the world. This study assessed the performance of the application of hybrid models, that is, Autoregressive Integrated Moving Average (ARIMA)-Artificial Neural Network (ANN), ARIMA-Support Vector Machine (SVM) and Principle Component Regression (PCR) along with Decision Tree (DT) and CatBoost deep learning model to predict the ambient PM2.5 concentrations. The data from January 2013 to May 2019 with 2342 observations were utilized in this study. Eighty percent of the data was used as training and the rest of the dataset was employed as testing. The performance of the models was evaluated by R2, RMSE and MAE value. Among the models, CatBoost performed best for predicting PM2.5 for all the stations. The RMSE values during the test period were 12.39 µg m−3, 13.06 µg m−3 and 12.97 µg m−3 for Dhaka, Narayanganj and Gazipur, respectively. Nonetheless, the ARIMA-ANN and DT methods also provided acceptable results. The study suggests adopting deep learning models for predicting atmospheric PM2.5 in Bangladesh.

Indoor Air Pollution with Fine Particles and Implications for Workers’ Health in Dental Offices: A Brief Review

(1) Background: Indoor air pollution can affect the well-being and health of humans. Sources of indoor pollution with particulate matter (PM) are outdoor particles and indoor causes, such as construction materials, the use of cleaning products, air fresheners, heating, cooking, and smoking activities. In 2017, according to the Global Burden of Disease study, 1.6 million people died prematurely because of indoor air pollution. The health effects of outdoor exposure to PM have been the subject of both research and regulatory action, and indoor exposure to fine particles is gaining more and more attention as a potential source of adverse health effects. Moreover, in critical situations such as the current pandemic crisis, to protect the health of the population, patients, and staff in all areas of society (particularly in indoor environments, where there are vulnerable groups, such as people who have pre-existing lung conditions, patients, elderly people, and healthcare professionals such as dental practitioners), there is an urgent need to improve long- and short-term health. Exposure to aerosols and splatter contaminated with bacteria, viruses, and blood produced during dental procedures performed on patients rarely leads to the transmission of infectious agents between patients and dental health care staff if infection prevention procedures are strictly followed. On the other hand, in the current circumstances of the pandemic crisis, dental practitioners could have an occupational risk of acquiring coronavirus disease as they may treat asymptomatic and minimally symptomatic patients. Consequently, an increased risk of SARS-CoV-2 infection could occur in dental offices, both for staff that provide dental healthcare and for other patients, considering that many dental procedures produce droplets and dental aerosols, which carry an infectious virus such as SARS-CoV-2. (2) Types of studies reviewed and applied methodology: The current work provides a critical review and evaluation, as well as perspectives concerning previous studies on health risks of indoor exposure to PM in dental offices. The authors reviewed representative dental medicine literature focused on sources of indoor PM10 and PM2.5 (particles for which the aerodynamic diameter size is respectively less than 10 and 2.5 μm) in indoor spaces (paying specific attention to dental offices) and their characteristics and toxicological effects in indoor microenvironments. The authors also reviewed representative studies on relations between the indoor air quality and harmful effects, as well as studies on possible indoor viral infections acquired through airborne and droplet transmission. The method employed for the research illustrated in the current paper involved a desk study of documents and records relating to occupational health problems among dental health care providers. In this way, it obtained background information on both the main potential hazards in dentistry and infection risks from aerosol transmission within dental offices. Reviewing this kind of information, especially that relating to bioaerosols, is critical for minimizing the risk to dental staff and patients, particularly when new recommendations for COVID-19 risk reduction for the dental health professional community and patients attending dental clinics are strongly needed. (3) Results: The investigated studies and reports obtained from the medical literature showed that, even if there are a wide number of studies on indoor human exposure to fine particles and health effects, more deep research and specific studies on indoor air pollution with fine particles and implications for workers’ health in dental offices are needed. As dental practices are at a higher risk for hazardous indoor air because of exposure to chemicals and microbes, the occupational exposures and diseases must be addressed, with special attention being paid to the dental staff. The literature also documents that exposure to fine particles in dental offices can be minimized by putting prevention into practice (personal protection barriers such as masks, gloves, and safety eyeglasses) and also keeping indoor air clean (e.g., high-volume evacuation, the use of an air-room-cleaning system with high-efficiency particulate filters, and regularly maintaining the air-conditioning and ventilation systems). These kinds of considerations are extremely important as the impact of indoor pollution on human health is no longer an individual issue, with its connections representing a future part of sustainability which is currently being redefined. These kinds of considerations are extremely important, and the authors believe that a better situation in dentistry needs to be developed, with researchers in materials and dental health trying to understand and explain the impact of indoor pollution on human health.

Spatial and Temporal Exposure Assessment to PM2.5 in a Community Using Sensor-Based Air Monitoring Instruments and Dynamic Population Distributions

This research was to conduct a pilot study for two consecutive days in order to assess fine particulate matter (PM2.5) exposure of an entire population in a community. We aimed to construct a surveillance system by analyzing the observed spatio-temporal variation of exposure. Guro-gu in Seoul, South Korea, was divided into 2,204 scale grids of 100 m each. Hourly exposure concentrations of PM2.5 were modeled by the inverse distance weighted method, using 24 sensor-based air monitoring instruments and the indoor-to-outdoor concentration ratio. Population distribution was assessed using mobile phone network data and indoor residential rates, according to sex and age over time. Exposure concentration, population distribution, and population exposure were visualized to present spatio-temporal variation. The PM2.5 exposure of the entire population of Guro-gu was calculated by population-weighted average exposure concentration. The average concentration of outdoor PM2.5 was 42.1 µg/m3, which was lower than the value of the beta attenuation monitor measured by fixed monitoring station. Indoor concentration was estimated using an indoor-to-outdoor PM2.5 concentration ratio of 0.747. The population-weighted average exposure concentration of PM2.5 was 32.4 µg/m3. Thirty-one percent of the population exceeded the Korean Atmospheric Environmental Standard for PM2.5 over a 24 h average period. The results of this study can be used in a long-term aggregate and cumulative PM2.5 exposure assessment, and as a basis for policy decisions on public health management among policymakers and stakeholders.

Inorganic pollutants in the indoor environment of the Moravian Library: assessment of Cd, Pb, Cu, and Zn in total suspended particles and dust using HR-CS GF-AAS

In this study, the occurrence of lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in the environment of the Moravian Library in Brno, the second largest library in Czechia, was in focus. The materials of interest were airborne particles, dust originating from books, and also book pages. Total suspended particles (TSP) were sampled in different areas of the library, including the reading room, the book depository, and an external book warehouse. Samples of dusts were obtained from the book-cleaning system, and, moreover, some pages taken from old books were also analyzed. Samples were microwave-digested and analyzed using graphite furnace high-resolution continuum source AAS (HR-CS GF-AAS). During the analysis, possibilities of the signal intensity modulation of the HR-CS technique were demonstrated and employed in order to determine Zn, an element which is rarely determined by GF-AAS. The median TSP concentrations (in ng/m³) were as follows: Pb, 4.4; Cd, 0.07; Cu, 2.6; and Zn, 20.9. Such concentrations are safely below allowed limits. Contents of Pb determined in dust samples and book pages were slightly higher (up to 707 and 38 mg/kg, respectively) than the usually reported values. However, none of these results indicate a potential risk to library staff or readers.

Evaluating the Effect of Ambient Concentrations, Route Choices, and Environmental (in)Justice on Students' Dose of Ambient NO2 While Walking to School at Population Scales

The commuting microenvironment accounts for a large part of students' diurnal exposure to air pollution, especially in cities in developed countries where air pollution is caused predominantly by vehicle traffic. Accurate quantification of students' exposure and pollution dose during their commute from home to school requires their home addresses and details of the schools they attend. Such details are usually inaccessible or difficult to obtain at population scales due to privacy issues. Therefore, estimates of students' exposure to, and dose of, air pollution at population scales have to rely on simulated origins and destinations, which may bias the results. This contribution overcomes this limitation by quantifying students' terrain-based dosage of ambient nitrogen dioxide (NO₂) during their commute from home to school while walking along (a) the shortest-distance routes and (b) an alternative lowest-dose route. This is determined at population scales for students in Auckland, New Zealand using a rich dataset of observed home addresses and schools attended for 14,091 walking students. This study also determines the bias introduced when using simulated addresses (as opposed to observed data) to calculate the same result. Finally, we examine exposure inequalities among students of different socioeconomic backgrounds at school, at home, and during walking commutes. Results show that only 17.48% of students in the whole of Auckland can find alternative lowest-dose routes. The portion is higher (26%) in central Auckland because of its better road network connectivity. The trade-off analysis identifies that for only about 30% of students, a 1% increase in route length is associated with a >1% reduction in dosage if using the alternative lowest-dose route. Greater benefits were observed in suburban Auckland (a less-polluted area) than in central Auckland, which highlights the importance of taking an alternative lowest-dose route, especially for students whose shortest-distance routes overlap with or run parallel to an arterial road. The use of simulated addresses resulted in underestimates of both the length and reduced dosage of the alternative routes by up to a quarter in comparison with the results derived from the observed data. Limited evidence of exposure inequality based on commuter exposure was found, but patterns in the central city were opposite to those in the suburbs.

Environmental Health Surveillance System for a Population Using Advanced Exposure Assessment

Human exposure to air pollution is a major public health concern. Environmental policymakers have been implementing various strategies to reduce exposure, including the 10th-day-no-driving system. To assess exposure of an entire population of a community in a highly polluted area, pollutant concentrations in microenvironments and population time–activity patterns are required. To date, population exposure to air pollutants has been assessed using air monitoring data from fixed atmospheric monitoring stations, atmospheric dispersion modeling, or spatial interpolation techniques for pollutant concentrations. This is coupled with census data, administrative registers, and data on the patterns of the time-based activities at the individual scale. Recent technologies such as sensors, the Internet of Things (IoT), communications technology, and artificial intelligence enable the accurate evaluation of air pollution exposure for a population in an environmental health context. In this study, the latest trends in published papers on the assessment of population exposure to air pollution were reviewed. Subsequently, this study proposes a methodology that will enable policymakers to develop an environmental health surveillance system that evaluates the distribution of air pollution exposure for a population within a target area and establish countermeasures based on advanced exposure assessment.

Levels of PM10 and PM2.5 and Respiratory Health Impacts on School-Going Children in Kenya

BACKGROUND

The respiratory system of children is vulnerable to exposure to particulate matter (PM) with a diameter of less than 2.5 and 10 μm (PM2.5 and PM10) or even lower.

OBJECTIVE

This study assessed PM10 and PM2.5 levels and respiratory health impacts on children in schools located in an industrialized suburb in Kenya.

METHOD

The PM10 and PM2.5 levels were sampled from five public primary schools in Athi River Township and a control school during the wet and dry seasons. Outdoor and classroom samples were collected concurrently on an 8-hour mean during school hours on two consecutive days in each school and analyzed using gravimetric techniques. Five hundred and seventy-eight (n = 578) pupils aged 9-14 years from these schools were also evaluated for symptoms of respiratory illnesses and lung function using a questionnaire and spirometric method, respectively, during the same periods.

RESULTS

Indoor median PM10 levels (μg/m3) ranged from 60.8-269.1 and 52.8-232.3 and PM2.5 values (μg/m3) of 17.7-52.4 and 28.5-75.5 during the dry and wet seasons, respectively. The control classrooms had significantly (p <0.05) lower median PM10 levels (μg/m3) of 5.2 and 4.2, and PM2.5 levels (μg/m3) of 3.5 and 3.0 during the respective seasons. Nearly all the classrooms in Athi River schools had PM2.5 and PM10 median levels that exceeded the World Health Organization (WHO) recommended levels. The indoor-to-outdoor ratios varied from 0.35-1.40 and 0.80-2.40 for PM10 and 0.30-0.80 and 0.80-1.40 for PM2.5 during the dry and wet seasons, respectively, suggesting higher levels in the classrooms during the wet season. The relative risk (RR) and odds ratio (OR) presented higher prevalence of respiratory diseases following PM exposure in all the Athi River schools than the control during the dry and wet seasons. At 95% CI, the RR and OR showed strong associations between high PM10 and PM2.5 levels and lung function deficits and vice versa. The association was more prevalent during the wet season.

CONCLUSIONS

The study calls for effective indoor air management programs in school environments to reduce PM exposure and respiratory health impacts.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

The research permit and approvals were obtained from the University of Nairobi/Kenyatta National Hospital Ethics and Research Committee (KNH-UoN ERC Reference: P599/08/2016) and the National Commission for Science, Technology and Innovation (Reference: NACOSTI/P/18/4268/25724).

COMPETING INTERESTS

The authors declare no competing financial interests.

Lung Health in Children in Sub-Saharan Africa: Addressing the Need for Cleaner Air

Air pollution is increasingly recognized as a global health emergency with its impacts being wide ranging, more so for low- and middle-income countries where both indoor and outdoor pollution levels are high. In Africa, more than 80% of children live in households which use unclean sources of energy. The effects of both indoor and outdoor pollution on lung health on children who are the most vulnerable to their effects range from acute lower respiratory tract infections to long-term chronic health effects. We reviewed the literature on the effects of air pollution in children in Sub-Saharan Africa from prenatal exposure, infancy and school-going children. Data from Sub-Saharan Africa on quantification of exposures both indoor and outdoor mainly utilizes modelling or self-reporting. Exposures to biomass not only increases the risk of acute respiratory tract infections in young children but also increases the risk of carriage of pathogenic bacteria in the upper respiratory tract. Although there is limited evidence of association between asthma and pollution in African children, airway hyper-responsiveness and lower lung function has been demonstrated in children with higher risk of exposure. Interventions at a policy level to both quantify the exposure levels at a population level are urgently needed to address the possible interventions to limit exposure and improve lung health in children in Sub-Saharan Africa.

How Do Combustion and Non-Combustion Products Used Outdoors Affect Outdoor and Indoor Particulate Matter Levels? A Field Evaluation Near the Entrance of an Italian University Library

Particulate Matter (PM) is a well-known health risk factor and pollutes both outdoor and indoor air. Using PM as an air pollution indicator, the aims were to assess outdoor and indoor air pollution due to combustion and/or non-combustion products used outdoors and to compare the PM levels emitted by different products. PM with an aerodynamic diameter ≤10, 4, 2.5 and 1 µm (PM₁₀, PM₄, PM_2.5, PM₁) was simultaneously measured in two areas, respectively, indoors (with smoking ban) and outdoors (where people commonly smoke) of a university library during the morning and the afternoon of two weekdays. Both combustion and non-combustion products determined a relevant worsening of outdoor air quality, with the highest PM₁ levels achieved when a single traditional cigarette (9920 µg m^-3), a single e-cigarette (9810 µg m^-3) and three simultaneous traditional cigarettes (8700 µg m^-3) were smoked. An increase of indoor PM₁ levels was found during outdoor smoking/vaping sessions, persisting also after the end of sessions. The results highlighted the need for a revision of smoke-free laws, especially for outdoor areas, to include non-combustion products. In addition, it is essential to make society aware of the dangers of smoking outdoors by implementing health promotion interventions.

A Combined Citizen Science—Modelling Approach for NO2 Assessment in Torino Urban Agglomeration

The #CHEARIATIRA citizen science campaign was developed in February 2019 in Torino (western part of the Po Valley megacity region). The aim of the campaign was public engagement with measuring NO2 concentrations in an urban area that often exceeds air quality standards. NO2 diffusion tubes were employed by citizens under our supervision. In this paper, we present the main outcomes of a combined approach between the #CHEARIATIRA campaign and the urban dispersion model SIRANE. The results were validated against the available public Air Quality Monitoring Stations (AQMS). The citizens’ passive samplers and the modelled data show a good response in central districts both during the campaign interval and by annual projection. Traffic hotspots and sensitive receptors (schools, hospital) have high concentrations of NO2. Most of the study area (83% of the tubes) is subject to an increased risk of premature death according to epidemiological literature.

Household Dust: Loadings and PM10-Bound Plasticizers and Polycyclic Aromatic Hydrocarbons

Residential dust is recognized as a major source of environmental contaminants, including polycyclic aromatic hydrocarbons (PAHs) and plasticizers, such as phthalic acid esters (PAEs). A sampling campaign was carried out to characterize the dust fraction of particulate matter with an aerodynamic diameter smaller than 10 µm (PM10), using an in situ resuspension chamber in three rooms (kitchen, living room, and bedroom) of four Spanish houses. Two samples per room were collected with, at least, a one-week interval. The PM10 samples were analyzed for their carbonaceous content by a thermo-optical technique and, after solvent extraction, for 20 PAHs, 8 PAEs and one non-phthalate plasticizer (DEHA) by gas chromatography-mass spectrometry. In general, higher dust loads were observed for parquet flooring as compared with tile. The highest dust loads were obtained for rugs. Total carbon accounted for 9.3 to 51 wt% of the PM10 mass. Plasticizer mass fractions varied from 5 µg g−1 to 17 mg g−1 PM10, whereas lower contributions were registered for PAHs (0.98 to 116 µg g−1). The plasticizer and PAH daily intakes for children and adults via dust ingestion were estimated to be three to four orders of magnitude higher than those via inhalation and dermal contact. The thoracic fraction of household dust was estimated to contribute to an excess of 7.2 to 14 per million people new cancer cases, which exceeds the acceptable risk of one per million.

Particulate Matter Measurement Indoors: A Review of Metrics, Sensors, Needs, and Applications

Many populations spend ∼90% of their time indoors, with household particulate matter being linked to millions of premature deaths worldwide. Particulate matter is currently measured using particle mass, particle number, and particle size distribution metrics, with other metrics, such as particle surface area, likely to be of increasing importance in the future. Particulate mass is measured using gravimetric methods, tapered element oscillating microbalances, and beta attenuation instruments and is best suited to use in compliance monitoring, trend analysis, and high spatial resolution measurements. Particle number concentration is measured by condensation particle counters, optical particle counters, and diffusion chargers. Particle number measurements are best suited to source characterization, trend analysis and ultrafine particle investigations. Particle size distributions are measured by gravimetric impactors, scanning mobility particle sizers, aerodynamic particle sizers, and fast mobility particle sizers. Particle size distribution measurements are most useful in source characterization and particulate matter property investigations, but most measurement options remain expensive and intrusive. However, we are on the cusp of a revolution in indoor air quality monitoring and management. Low-cost sensors have potential to facilitate personalized information about indoor air quality (IAQ), allowing citizens to reduce exposures to PM indoors and to resolve potential dichotomies between promoting healthy IAQ and energy efficient buildings. Indeed, the low cost will put this simple technology in the hands of citizens who wish to monitor their own IAQ in the home or workplace, to inform lifestyle decisions. Low-cost sensor networks also look promising as the solution to measuring spatial distributions of PM indoors, however, there are important sensor/data quality, technological, and ethical barriers to address with this technology. An improved understanding of epidemiology is essential to identify which metrics correlate most with health effects, allowing indoor specific PM standards to be developed and to inform the future of experimental applications.

Evaluation of Personal Exposure to Surgical Smoke Generated from Electrocautery Instruments: A Pilot Study

Hospital technician surgical smoke exposures during several types of electrocautery-based procedures were evaluated. Personal and area air sampling was performed for 106 individual analytes including ultrafine particulate matter (UFP), volatile organic compounds, polycyclic aromatic hydrocarbons, phenol, aldehydes, carbon monoxide, hydrogen sulfide, and hydrogen cyanide. Acetone, d-limonene, ethanol, ethyl acetate, and fluorene were measured in surgical suites at concentrations 1.1- to 3.7-fold higher than those observed in background. Benzene, α-pinene, methylene chloride, and n-hexane were measured in the absence of a detectable background concentration. All analytes were measured at concentrations that were <1% of the corresponding US federal and state 8-h permissible exposure limits (PELs), if PELs existed. Full-shift average UFP concentrations ranged from 773 to 2257 particles/cm3, approximately one order of magnitude higher than surgical suite background concentrations. A comparison of two breast reduction procedures suggested that the use of smoke evacuators reduced UFP exposure by 6-fold. We concluded that selection and evaluation of key hazards, particularly UFP, under a variety of experimental conditions would be beneficial to elucidate potential health effects and causes osf employee complaints. Recommendations for successful sampling campaigns in future surgical smoke occupational exposure studies are provided. We also recommend the continued use of engineering controls, local exhaust ventilation, and surgical N95 respirators to reduce personal exposures to UFP in surgical smoke.

Indoor vs. outdoor airborne element array: A novel approach using moss bags to explore possible pollution sources

This study investigated by the moss-bag approach the pattern of air dispersed elements in 12 coupled indoor/outdoor exposure sites, all located in urban and rural residential areas. The aims were to discriminate indoor vs. outdoor element composition in coupled exposure sites and find possible relation between moss elemental profile and specific characteristics of each exposure site. Elements were considered enriched when in 60% of the sites, post-exposure concentration exceeded pre-exposure concentration plus two folds the standard deviation. Of the 53 analyzed elements, 15 (As, B, Ca, Co, Cr, Cu, Mn, Mo, Ni, Sb, Se, Sn, Sr, V, Zn) were enriched in moss exposed outdoor, whereas a subset of 7 elements (As, B, Cr, Mo, Ni, Se, V) were enriched also in indoor moss samples. The cluster analysis of the sites based on all elements, clearly separated samples in two groups corresponding to mosses exposed indoor and outdoor, with the latter generally exceeding the first. Among outdoor sites, urban were most impacted than rural; whereas other factors (e.g., heating and cooking systems, building material, residence time and family life style) could affect element profile of indoor environments. Based on the indoor/outdoor ratio, As derived from outdoor and indoor sources, B, Mo and Se were enriched mostly in outdoor sites; Ni, Cr and V were specifically enriched in most indoor samples, supporting the presence of indoor emitting sources for these elements. A PCA of all indoor sites based on enriched elements and site characteristics showed that traffic affected indoor pollution in urban areas. The moss bag approach provided useful information for a global assessment of human exposure.

Recent Advances in Urban Ventilation Assessment and Flow Modelling

The Atmosphere Special Issue “Recent Advances in Urban Ventilation Assessment and FlowModelling” collects twenty-one original papers and one review paper published in 2017[...]

Particle/Gas Partitioning of Phthalates to Organic and Inorganic Airborne Particles in the Indoor Environment

The particle/gas partition coefficient K_p is an important parameter affecting the fate and transport of indoor semivolatile organic compounds (SVOCs) and resulting human exposure. Unfortunately, experimental measurements of K_p exist almost exclusively for atmospheric polycyclic aromatic hydrocarbons, with very few studies focusing on SVOCs that occur in indoor environments. A specially designed tube chamber operating in the laminar flow regime was developed to measure K_p of the plasticizer di-2-ethylhexyl phthalate (DEHP) for one inorganic (ammonium sulfate) and two organic (oleic acid and squalane) particles. The values of K_p for the organic particles (0.23 ± 0.13 m³/μg for oleic acid and 0.11 ± 0.10 m³/μg for squalane) are an order of magnitude higher than those for the inorganic particles (0.011 ± 0.004 m³/μg), suggesting that the process by which the particles accumulate SVOCs is different. A mechanistic model based on the experimental design reveals that the presence of the particles increases the gas-phase concentration gradient in the boundary layer, resulting in enhanced mass transfer from the emission source into the air. This novel approach provides new insight into experimental designs for rapid K_p measurement and a sound basis for investigating particle-mediated mass transfer of SVOCs.