Ultrafine particles from electric appliances and cooking pans: experiments suggesting desorption/nucleation of sorbed organics as the primary source

Human exposure to aerosol from indoor gas stove cooking and the resulting cardiovascular system responses

The effect of cooking aerosol on the human heart was investigated in this study. The heart rate and blood pressure of 33 healthy adults were monitored before, exactly after, and two hours post-exposure (30 minutes, 60 minutes, 90 minutes, and 120 minutes after cooking). One hundred twenty grams of ground beef was fried in sunflower oil for twenty minutes using a gas stove without ventilation. Ultrafine particles, indoor temperature, relative humidity, carbon dioxide, oil, and meat temperatures were monitored during the experiment. The average particle emission rate (S) and average decay rate (a+k) for meat frying were found to be 2.09×1013 (SD=3.94 ×1013, R2=0.98, P <0.0001) particles/min, and 0.055 (SD=0.019, R2=0.91, P <0.0001) particles/min, respectively. No statistically significant changes in diastolic blood pressure (DBP) and heart rate (HR) were observed. The average systolic blood pressure (SBP) statistically significantly increased from 98 mmHg (before the exposure) to 106 mmHg 60 minutes after the exposure. The results suggested that frying emission statistically significantly impacted blood pressure.

Influence of Ventilation on Formation and Growth of 1-20 nm Particles via Ozone-Human Chemistry

Ozone reaction with human surfaces is an important source of ultrafine particles indoors. However, 1-20 nm particles generated from ozone-human chemistry, which mark the first step of particle formation and growth, remain understudied. Ventilation and indoor air movement could have important implications for these processes. Therefore, in a controlled-climate chamber, we measured ultrafine particles initiated from ozone-human chemistry and their dependence on the air change rate (ACR, 0.5, 1.5, and 3 h-1) and operation of mixing fans (on and off). Concurrently, we measured volatile organic compounds (VOCs) and explored the correlation between particles and gas-phase products. At 25-30 ppb ozone levels, humans generated 0.2-7.7 × 1012 of 1-3 nm, 0-7.2 × 1012 of 3-10 nm, and 0-1.3 × 1012 of 10-20 nm particles per person per hour depending on the ACR and mixing fan operation. Size-dependent particle growth and formation rates increased with higher ACR. The operation of mixing fans suppressed the particle formation and growth, owing to enhanced surface deposition of the newly formed particles and their precursors. Correlation analyses revealed complex interactions between the particles and VOCs initiated by ozone-human chemistry. The results imply that ventilation and indoor air movement may have a more significant influence on particle dynamics and fate relative to indoor chemistry.

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.

Exposure characteristics and risk assessment of air particles in a Chinese hotel kitchen

Background

The hazards of kitchen particles have attracted social attention, but their distribution characteristics and risk assessment are rarely reported.

Objective

To explore the temporal and spatial distribution characteristics of kitchen particles, analyze the variations in characteristics of number concentration (NC), mass concentration (MC), surface area concentration (SAC), and particle size distribution, provide reference indexes for evaluating worker exposure, evaluate the risk of kitchen particles, as well as suggest improvements and control measures.

Patients and methods

Different cooking posts in a Chinese hotel kitchen were selected to monitor exposure to particles, explore the temporal and spatial distribution characteristics of NC, MC, and SAC of particles in the cooking post, analyze changes in the particle size, compare the individual exposure of particles between the cooking and steaming posts, and analyze the correlation between NC, MC, and SAC. Risk assessment of kitchen ultrafine particles was performed using a Nanotool.

Results

The sizes and fluctuation ranges of NC_{10 - 500nm} at cooking posts during lunch preparation and at peak periods were significantly higher than those at the end of the lunch period. The mean values of MC_{10 - 500nm} during the lunch preparation peak and ending periods were 0.149, 0.229, and 0.151 mg m^-3, respectively. The mean values of SAC_{10 - 500nm} were 225, 961, and 466 μm²·cm^-3, respectively. The mode diameter of exposed particles at the cooking post [(34.98 ± 2.33) nm] was higher than that at the steaming post [(30.11 ± 2.17) nm] (P < 0.01). The correlation between SAC_{10 - 500nm} and NC_{10 - 500nm} (r = 0.703) was the strongest. Nanotool gave a hazard rating ratio, exposure rating ratio, and risk ratio of 0.75.

Conclusion

The sizes of the NC, MC, and SAC of the particles at the cooking post were related to the kitchen operations. Since kitchen particles are of high exposure and risk levels, protective measures should be formulated and implemented to deal with them safely.

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.

Temperature and indoor environments

From the thermodynamic perspective, the term temperature is clearly defined for ideal physical systems: A unique temperature can be assigned to each black body via its radiation spectrum, and the temperature of an ideal gas is given by the velocity distribution of the molecules. While the indoor environment is not an ideal system, fundamental physical and chemical processes, such as diffusion, partitioning equilibria, and chemical reactions, are predictably temperature-dependent. For example, the logarithm of reaction rate and equilibria constants are proportional to the reciprocal of the absolute temperature. It is therefore possible to have non-linear, very steep changes in chemical phenomena over a relatively small temperature range. On the contrary, transport processes are more influenced by spatial temperature, momentum, and pressure gradients as well as by the density, porosity, and composition of indoor materials. Consequently, emergent phenomena, such as emission rates or dynamic air concentrations, can be the result of complex temperature-dependent relationships that require a more empirical approach. Indoor environmental conditions are further influenced by the thermal comfort needs of occupants. Not only do occupants have to create thermal conditions that serve to maintain their core body temperature, which is usually accomplished by wearing appropriate clothing, but also the surroundings must be adapted so that they feel comfortable. This includes the interaction of the living space with the ambient environment, which can vary greatly by region and season. Design of houses, apartments, commercial buildings, and schools is generally utility and comfort driven, requiring an appropriate energy balance, sometimes considering ventilation but rarely including the impact of temperature on indoor contaminant levels. In our article, we start with a review of fundamental thermodynamic variables and discuss their influence on typical indoor processes. Then, we describe the heat balance of people in their thermal environment. An extensive literature study is devoted to the thermal conditions in buildings, the temperature-dependent release of indoor pollutants from materials and their distribution in the various interior compartments as well as aspects of indoor chemistry. Finally, we assess the need to consider temperature holistically with regard to the changes to be expected as a result of global emergencies such as climate change.

Ventilation Systems and Their Impact on Nanoparticle Concentrations in Office Buildings

Nanoparticles (NPs) can infiltrate indoor environments and have a large impact on human health when inhaled. Thus, indoor air quality is highly dependent on the outdoor air and on the filters used in the ventilation systems. In the NanoOffice study, the concentrations and the size distribution of NPs were measured with a five-minute time resolution in twelve office buildings in Umeå. Measurements were taken with an SMPS 3938 during a one-week period in the heating and nonheating seasons. Large differences in ventilation between buildings appeared, despite the fact that similar MVHR ventilation systems were used, and most of them were equipped with F7 filters. The NP concentrations and the simultaneous ventilation flows were measured in buildings with a variable and a more constant ventilation flow. In some cases, an increase in NP concentration could be seen after ventilation turn-on or after an increase in the ventilation flow. There was also one case where the NP concentrations increased in connection with the ventilation being switched off or reducing its flow. However, variable NP concentrations were also shown in buildings with a fairly constant ventilation flow, which was prominent for the two buildings located closest to busy streets. The correlation coefficients between the ventilation flow and particles in different size classes were in general smallest for particles in the smallest size classes, indicating higher filtration efficiency.

Indoor and Outdoor Nanoparticle Concentrations in an Urban Background Area in Northern Sweden: The NanoOffice Study

In recent years, nanoparticles (NPs) have received much attention due to their very small size, high penetration capacity, and high toxicity. In urban environments, combustion-formed nanoparticles (CFNPs) dominate in particle number concentrations (PNCs), and exposure to those particles constitutes a risk to human health. Even though fine particles (<2.5 µm) are regularly monitored, information on NP concentrations, both indoors and outdoors, is still limited. In the NanoOffice study, concentrations of nanoparticles (10–300 nm) were measured both indoors and outdoors with a 5-min time resolution at twelve office buildings in Umeå. Measurements were taken during a one-week period in the heating season and a one-week period in the non-heating season. The measuring equipment SMPS 3938 was used for indoor measurements, and DISCmini was used for outdoor measurements. The NP concentrations were highest in offices close to a bus terminal and lowest in offices near a park. In addition, a temporal effect appeared, usually with higher concentrations of nanoparticles found during daytime in the urban background area, whereas considerably lower nanoparticle concentrations were often present during nighttime. Infiltration of nanoparticles from the outdoor air into the indoor air was also common. However, the indoor/outdoor ratios (I/O ratios) of NPs showed large variations between buildings, seasons, and time periods, with I/O ratios in the range of 0.06 to 0.59. The reasons for high indoor infiltration rates could be NP emissions from adjacent outdoor sources. We could also see particle growth since the indoor NPs were, on average, almost twice as large as the NPs measured outdoors. Despite relatively low concentrations of NPs in the urban background air during nighttime, they could rise to very high daytime concentrations due to local sources, and those particles also infiltrated the indoor air.

Particle number emission rates of aerosol sources in 40 German households and their contributions to ultrafine and fine particle exposure

More representative data on source-specific particle number emission rates and associated exposure in European households are needed. In this study, indoor and outdoor particle number size distributions (10-800 nm) were measured in 40 German households under real-use conditions in over 500 days. Particle number emission rates were derived for around 800 reported indoor source events. The highest emission rate was caused by burning candles (5.3 × 10¹³  h^-1 ). Data were analyzed by the single-parameter approach (SPA) and the indoor aerosol dynamics model approach (IAM). Due to the consideration of particle deposition, coagulation, and time-dependent ventilation rates, the emission rates of the IAM approach were about twice as high as those of the SPA. Correction factors are proposed to convert the emission rates obtained from the SPA approach into more realistic values. Overall, indoor sources contributed ~ 56% of the daily-integrated particle number exposure in households under study. Burning candles and opening the window leads to seasonal differences in the contributions of indoor sources to residential exposure (70% and 40% in the cold and warm season, respectively). Application of the IAM approach allowed to attribute the contributions of outdoor particles to the penetration through building shell and entry through open windows (26% and 15%, respectively).

HVAC filtration of particles and trace metals: Airborne measurements and the evaluation of quantitative filter forensics

Filters installed in the heating, ventilation, and air-conditioning (HVAC) systems can serve as air-cleaning and sampling devices for indoor particles. The purpose of this article is to evaluate these dual roles. An occupied home with a central HVAC system equipped with a Minimum Efficiency Reporting Value (MERV, from ASHRAE Standard 52.2) 11 filter was monitored for six weeks. Weekly airborne gravimetric and real-time sampling was performed to measure the particle size distribution and the concentration of total suspended particles (TSP), PM₁₀, PM_2.5, PM₁, and 12 trace metals. The weekly system runtimes were intentionally changed to provide a wide range of weekly filtration volumes. The quantitative filter forensics (QFF) concentrations of particulate matter (PM) and trace metals were calculated using the analysis of the dust collected on the HVAC filter, the filtration volume, and filter in-situ efficiency. The results indicated that filtration was not influential to remove PM and trace metals as the concentrations during the weeks with continuous HVAC operation were not consistently lower than those during the other weeks. This suggests the dominance of other particle and trace metal source and loss mechanisms weakens the influence of filtration in this home. The QFF evaluation results indicated that the concentration of TSP and over half of the tested trace metals (e.g., Pb, Cd, Ni, V, Sb, K, and Sr) could be estimated by QFF within a factor of two when compared to airborne sampling results. PM₁₀, PM_2.5, and PM₁ concentrations were significantly underestimated by QFF potentially due to the limitations of size distribution analysis by a laser diffraction particle sizer (LDPS) for the detection of <1 μm particles. Overall, while QFF was promising for TSP and some trace metals, improvement in size distribution analysis could extend the application of QFF for airborne sampling.

Real-time indoor PM2.5 monitoring in an urban cohort: Implications for exposure disparities and source control

Fine particulate matter (PM2.5) concentrations are highly variable indoors, with evidence for exposure disparities. Real-time monitoring coupled with novel statistical approaches can better characterize drivers of elevated PM2.5 indoors. We collected real-time PM2.5 data in 71 homes in an urban community of Greater Boston, Massachusetts using Alphasense OPC-N2 monitors. We estimated indoor PM2.5 concentrations of non-ambient origin using mass balance principles, and investigated their associations with indoor source activities at the 0.50 to 0.95 exposure quantiles using mixed effects quantile regressions, overall and by homeownership. On average, the majority of indoor PM2.5 concentrations were of non-ambient origin (≥77%), with a higher proportion at increasing quantiles of the exposure distribution. Major source predictors of non-ambient PM2.5 concentrations at the upper quantile (0.95) were cooking (1.4-23 μg/m3) and smoking (15 μg/m3, only among renters), with concentrations also increasing with range hood use (3.6 μg/m3) and during the heating season (5.6 μg/m3). Across quantiles, renters in multifamily housing experienced a higher proportion of PM2.5 concentrations from non-ambient sources than homeowners in single- and multifamily housing. Renters also more frequently reported cooking, smoking, spray air freshener use, and second-hand smoke exposure, and lived in units with higher air exchange rate and building density. Accounting for these factors explained observed PM2.5 exposure disparities by homeownership, particularly in the upper exposure quantiles. Our results suggest that renters in multifamily housing may experience higher PM2.5 exposures due to a combination of behavioral and building factors that are amenable to intervention.

Characterization of Ultrafine Particles and VOCs Emitted from a 3D Printer

Currently, widely available three-dimensional (3D) printers are very popular with the public. Previous research has shown that these printers can emit ultrafine particles (UFPs) and volatile organic compounds (VOCs). Several studies have examined the emissivity of filaments from 3D printing, except glycol modified polyethylene terephthalate (PETG) and styrene free co-polyester (NGEN) filaments. The aim of this study was to evaluate UFP and VOC emissions when printing using a commonly available 3D printer (ORIGINAL PRUSA i3 MK2 printer) using PETG and NGEN. The concentrations of UFPs were determined via measurements of particle number concentration and size distribution. A thermal analysis was carried out to ascertain whether signs of fiber decomposition would occur at printing temperatures. The total amount of VOCs was determined using a photoionization detector, and qualitatively analyzed via gas chromatography-mass spectrometry. The total particle concentrations were 3.88 × 10¹⁰ particles for PETG and 6.01 × 10⁹ particles for NGEN. VOCs at very low concentrations were detected in both filaments, namely ethylbenzene, toluene, and xylene. In addition, styrene was identified in PETG. On the basis of our results, we recommend conducting additional measurements, to more accurately quantify personal exposure to both UFPs and VOCs, focusing on longer exposure as it can be a source of potential cancer risk.

The impact on heart rate and blood pressure following exposure to ultrafine particles from cooking using an electric stove

Cooking is a major source of indoor particulate matter (PM), especially ultrafine particles (UFPs). Long-term exposure to fine and ultrafine particles (UFPs) has been associated with adverse human health effects. Toxicological studies have demonstrated that exposure to PM_2.5 (particles with aerodynamic diameter smaller than 2.5 μm) may result in increased blood pressure (BP). Some clinical studies have shown that acute exposure to PM_2.5 causes changes in systolic (SBP) and diastolic blood pressure (DBP), depending on the source of particles. Studies assessing the effect of exposure to cooking PM on BP and heart rate (HR) using electric or gas stoves are not well represented in the literature. The aim of this investigation was to perform controlled studies to quantify the exposure of 50 healthy volunteer participants to fine and ultrafine particles emitted from a low-emissions recipe for frying ground beef on an electric stove. The BP and heart rate (HR) of the volunteers were monitored during exposure and after the exposure (2 h post-exposure). Maximum UFP and PM_2.5 concentrations were 6.5 × 10⁴ particles/cm³ and 0.017 mg/m³, respectively. Exposure to UFPs from frying was associated with statistically significant increases in the SBP. The lack of food and drink during the 2 h post-cooking period was also associated with a statistically significant reduction in SBP. No statistically significant changes in DBP were observed. Physiological factors, including heat stress over the stove, movements and anxiety, could be responsible for an elevation in HR at the early stages of the experiments with a subsequent drop in HR after 90 min post-cooking, when study participants were relaxed in a living room.

Chemical Composition, Spatial Homogeneity, and Growth of Indoor Surface Films

Organic films on indoor surfaces are ubiquitous, but details about their composition and growth over timescales less than a month are not fully understood. To address these gaps in understanding, organic film samples in an apartment unit were collected over the course of 17 days using passive samplers and analyzed in a non-targeted manner using direct analysis in real-time mass spectrometry (DART-MS). Overall, the chemical composition observed across various locations within the apartment are very similar. Mass spectra also show clear evidence for the growth of semi-volatile compounds from natural sources and consumer products, such as carboxylic acids and plasticizers. Certain compounds show evidence for equilibration, mostly consistent with surface partitioning models based on octanol-air partition coefficients (K_oa). Compounds which have higher molecular weight or larger K_oa values tend to equilibrate later, leading to an overall shift in the composition of the film as a function of collection time. Growth rates of film thickness are at least 0.05 nm/day based on a limited number of individually calibrated ions.

Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures

It is important to improve our understanding of exposure to particulate matter (PM) in residences because of associated health risks. The HOMEChem campaign was conducted to investigate indoor chemistry in a manufactured test house during prescribed everyday activities, such as cooking, cleaning, and opening doors and windows. This paper focuses on measured size distributions of PM (0.001-20 μm), along with estimated exposures and respiratory-tract deposition. Number concentrations were highest for sub-10 nm particles during cooking using a propane-fueled stovetop. During some cooking activities, calculated PM_2.5 mass concentrations (assuming a density of 1 g cm^-3) exceeded 250 μg m^-3, and exposure during the postcooking decay phase exceeded that of the cooking period itself. The modeled PM respiratory deposition for an adult residing in the test house kitchen for 12 h varied from 7 μg on a day with no indoor activities to 68 μg during a simulated day (including breakfast, lunch, and dinner preparation interspersed by cleaning activities) and rose to 149 μg during a simulated Thanksgiving day.

Exposure to Submicron Particles and Estimation of the Dose Received by Children in School and Non-School Environments

In the present study, the daily dose in terms of submicron particle surface area received by children attending schools located in three different areas (rural, suburban, and urban), characterized by different outdoor concentrations, was evaluated. For this purpose, the exposure to submicron particle concentration levels of the children were measured through a direct exposure assessment approach. In particular, measurements of particle number and lung-deposited surface area concentrations at “personal scale” of 60 children were performed through a handheld particle counter to obtain exposure data in the different microenvironments they resided. Such data were combined with the time–activity pattern data, characteristics of each child, and inhalation rates (related to the activity performed) to obtain the total daily dose in terms of particle surface area. The highest daily dose was estimated for children attending the schools located in the urban and suburban areas (>1000 mm2), whereas the lowest value was estimated for children attending the school located in a rural area (646 mm2). Non-school indoor environments were recognized as the most influential in terms of children’s exposure and, thus, of received dose (>70%), whereas school environments contribute not significantly to the children daily dose, with dose fractions of 15–19% for schools located in urban and suburban areas and just 6% for the rural one. Therefore, the study clearly demonstrates that, whatever the school location, the children daily dose cannot be determined on the basis of the exposures in outdoor or school environments, but a direct assessment able to investigate the exposure of children during indoor environment is essential.

A new exposure route to trace elements in indoor particulate matter

Concentrations and emission rates of sixteen trace elements in emitted PM during heating soybean oil using three types of pans, including Teflon, granitium, and cast-iron, were investigated. Statistically significant decreases in Mn and Co emission rates were observed when the oil was heated in the cast-iron pan compared to Teflon and granitium pans. Among the released trace elements, Ni, Ba, Zn, and Cr had more contribution to the emission rate. The concentrations of Fe in the emitted PM₁ were found to be higher when cast-iron pan (8.49 ± 3.35 µg/m³ ) was utilized compared to Teflon (8.05 ± 2.27 µg/m³ ) and granitium (7.45 ± 1.38 µg/m³ ). However, these increases were statistically insignificant. The results of our study support the hypothesis that the trace elements translocate from cooking pans into the heated oil and subsequently to the particulate phase. This translocation creates a new inhalation exposure route to trace elements in indoor environments.

Evaluation of the effectiveness of a portable air cleaner in mitigating indoor human exposure to cooking-derived airborne particles

Gas cooking is an important source of airborne particulate matter (PM) indoors. Exposure to cooking-derived PM can lead to adverse human health impacts on non-smokers, especially in poorly-ventilated residential homes. Most of the previous studies on gas cooking emissions mainly focused on fine particles (PM_2.5) with little information on their size-fractionation. Moreover, studies dealing with mitigation of indoor human exposure to cooking-derived PM are currently sparse. Therefore, a systematic study was conducted to investigate the characteristics of PM_2.5 and size-fractionated PM derived from five commonly used cooking methods, namely, steaming, boiling, stir-frying, pan-frying and deep-frying in a poorly-ventilated domestic kitchen under controlled experimental conditions. Additionally, an indoor portable air cleaner was employed as a mitigation device to capture cooking-derived PM and improve indoor air quality (IAQ). Results revealed that the oil-based deep-frying cooking released the highest airborne particles which were about 170 folds higher compared to the baseline levels for PM_2.5 mass concentrations. The use of the air cleaner showed a statistically significant (p < 0.05) reduction in the indoor PM_2.5 levels. Moreover, PM_<0.25 (particles with diameter ≤ 250 nm) showed a very high mass concentration (378.2 μg/m³) during deep-frying, raising human health concern. A substantial reduction (~60-85%) in PM_<0.25 mass concentrations and their total respiratory deposition doses (RDD) in the human respiratory tract was observed while using the air cleaner during the five cooking methods. Furthermore, morphological characteristics and the relative abundance of trace elements in cooking-derived PM were also investigated. This study provides useful insights into the assessment and mitigation of indoor human exposure to cooking-derived PM.

Quantification of the impact of cooking processes on indoor concentrations of volatile organic species and primary and secondary organic aerosols

Cooking is recognized as an important source of particulate pollution in indoor and outdoor environments. We conducted more than 100 individual experiments to characterize the particulate and non-methane organic gas emissions from various cooking processes, their reaction rates, and their secondary organic aerosol yields. We used this emission data to develop a box model, for simulating the cooking emission concentrations in a typical European home and the indoor gas-phase reactions leading to secondary organic aerosol production. Our results suggest that about half of the indoor primary organic aerosol emission rates can be explained by cooking. Emission rates of larger and unsaturated aldehydes likely are dominated by cooking while the emission rates of terpenes are negligible. We found that cooking dominates the particulate and gas-phase air pollution in non-smoking European households exceeding 1000 μg m-3 . While frying processes are the main driver of aldehyde emissions, terpenes are mostly emitted due to the use of condiments. The secondary aerosol production is negligible with around 2 μg m-3 . Our results further show that ambient cooking organic aerosol concentrations can only be explained by super-polluters like restaurants. The model offers a comprehensive framework for identifying the main parameters controlling indoor gas- and particle-phase concentrations.

Characteristics of cooking-generated PM10 and PM2.5 in residential buildings with different cooking and ventilation types

The fine particles (PM_2.5, PM₁₀) have worsened indoor air quality and have caused an adverse effect on health. While range hoods have been typically used to exhaust cooking-generated fine particles in residential buildings, it is difficult to remove the fine particles effectively. The present study analyzed the effect of cooking on indoor air quality through the on-site measurements of cooking-generated fine particles (PM_2.5 and PM₁₀) in 30 residential buildings. The results of the field measurement showed that the fine particles occurred during the cooking and the concentration exceeded the Korean indoor fine particle concentration standards for PM₁₀ and PM_2.5. The particle decay rate constant in field measurement was 1.27-21.83 h^-1. The emission rates were 0.39-20.45 mg/min. In addition, the fine particles were measured in the experimental building by varying the cooking methods and ventilation types. Four different cooking methods were selected including broiling fish, meat, frying egg, and meat. By operating the range, hood system and the natural ventilation, the dispersion of the fine particle concentration, the particle emission rate, decay rate constant, and the Living-Kitchen (L/K) Ratio change was evaluated quantitatively. Based on the obtained results, the maximum concentrations of the fine particles were measured when broiling fish. Moreover, the range hood system was not able to decrease the cooking-emitted particle concentration effectively during the cooking period. The cooking-emitted particles were removed rapidly when both natural ventilation and the range hood system were operated simultaneously, where the particle decay rate constant was approximately 9 h^-1. Furthermore, the selection of cooking type was the most important factor that can significantly have an impact on indoor particle concentrations. Cooking - generated particles; Range hood; Particle decay rate constant; Living-Kitchen (L/K); PM2.5; Emission rate.

Are cell phones an indicator of personal exposure to organophosphate flame retardants and plasticizers?

BACKGROUND

Exposure to organophosphate ester (OPE) flame retardants and plasticizers is widespread and is of concern due to their toxicity.

OBJECTIVES

To investigate relationships between and within OPE concentrations in air, dust, hands, electronic product wipes and urinary metabolites with the goal of identifying product sources and exposure pathways.

METHODS

Women in Toronto and Ottawa, Canada, provided a urine sample, two sets of hand wipes, access to their homes for air and dust sampling, and completed a questionnaire. OPE concentrations were obtained for air and floor dust in the bedroom (n = 51) and most used room (n = 26), hand wipes (n = 204), and surface wipes of handheld (n = 74) and non-handheld electronic devices (n = 125). All air, dust and wipe samples were analyzed for 23 OPE compounds; urine samples (n = 44) were analyzed for 8 OPE metabolites.

RESULTS

Five-8 OPEs were detected in >80% of samples depending on the sample type. OPE median concentrations in hand wipes taken 3 weeks apart were not significantly different. Palms had higher concentrations than the back of hands; both were significantly correlated. Concentrations of 9 OPEs were significantly higher in surface wipes of handheld than non-handheld electronic devices. Six OPEs in hand wipes were significantly correlated with cell phone wipes, with two to four OPEs significantly correlated with tablet, laptop and television wipes. Multiple regression models using hand wipes, cell phone wipes and dust explained 8-33% of the variation in creatinine-adjusted urinary metabolites; air concentrations did not have explanatory power. OPEs in cell phone wipes explained the greatest variation in urinary metabolites.

CONCLUSIONS

Handheld electronic devices, notably cell phones, may either be sources or indicators of OPE exposure through hand-to-mouth and/or dermal uptake.

Contributions of burner, pan, meat and salt to PM emission during grilling

Grilling ground beef meat was conducted in two locations at Nazarbayev University, Kazakhstan. The experiments were designed such that only particles from beef meat were isolated. A similar experimental protocol was applied at both locations. The average particle number and mass emission rates for grilling pure meat itself (excluding particles from pan and burner) were found to be 9.4 × 10¹²(SD = 7.2 × 10¹² particle min^-1 and 7.6 × 10 (SD = 6.3 × 10) mg.min^-1, respectively. The PM emissions (number and mass) from the burner were found to be negligible compared to the pan and meat emissions. Ultrafine particle (UFP) concentrations from the heated pan itself were comparable to those of grilled meat. However, the particle mass concentrations from the pan itself were negligible. Approximately an hour of continuous heating resulted in zero emissions from the pan.

Cooking behaviors are related to household particulate matter exposure in children with asthma in the urban East Bay Area of Northern California

BACKGROUND

Asthma is a common childhood disease that leads to many missed days of school and parents' work. There are multiple environmental contributors to asthma symptoms and understanding the potential factors inside children's homes is crucial.

METHODS

This is a dual cohort study measuring household particulate matter (PM2.5), behaviors, and factors that influence air quality and asthma symptoms in the urban homes of children (ages 6-10) with asthma; one cohort had cigarette smoke exposure in the home (n = 13) and the other did not (n = 22). Exposure data included measurements every 5 minutes for a month.

RESULTS

In the entire study population, a large contributor to elevations in indoor PM2.5 above 35 μg/m3 was not using the stove hood when cooking (8.5% higher, CI 3.1-13.9%, p<0.005). Median PM values during cooking times were 0.88 μg/m3 higher than those during non-cooking times (95% CI 0.33-1.42). Mean monthly household PM2.5 level was significantly related to the presence of a cigarette smoker in the home (10.1 μg/m3 higher, 95% CI 5.2-15.1, p<0.001) when controlling for use of the stove hood and proximity to major roadway. There was a trend toward increased odds of persistent asthma with increases in average monthly PM2.5 (OR 1.1, 95% CI 0.97-1.3, p = 0.16).

CONCLUSIONS

Consideration of only outdoor PM2.5 may obscure potentially modifiable risks for asthma symptoms. Specifically, this preliminary study suggests that cooking behaviors may contribute to the burden of PM2.5 in the homes of children with asthma and thus to asthma symptoms.

Physicochemical characterization of aerosol particles emitted by electrical appliances

Adverse health effects of airborne particulate matter depend on parameters like particle size, particle surface and chemical composition. Major emission of indoor particles is caused by combustion processes like tobacco smoking and cooking. Nevertheless, the use of household electrical appliances, such as vacuum cleaners, flat irons or hair dryers, can produce particles as well. In this study the emissions of different hair dryers and flat irons were investigated using a test chamber. The particle number concentrations, particle volume concentrations, as well as the size distributions were measured. Particles were sampled and analyzed by electron microscopy, inductively coupled plasma mass spectrometry and gas chromatography mass spectrometry. Moreover different volatile organic compounds (VOCs) were measured. Each tested appliance, especially flat irons produced small particles with diameters far below 100nm and might be a nonnegligible source for indoor particles. Copper was the main identified element in most of the particles emitted from hair dryers, but in the emission of two hair dryers silver-containing nanoparticles were found as well. Various VOCs were observed in the emission of both flat irons and hair dryers, while cyclic siloxanes were detected only in the emission of flat irons. The use of flat irons or hair dryers may significantly contribute to the personal particle exposure.

Indoor Chemistry

This review aims to encapsulate the importance, ubiquity, and complexity of indoor chemistry. We discuss the many sources of indoor air pollutants and summarize their chemical reactions in the air and on surfaces. We also summarize some of the known impacts of human occupants, who act as sources and sinks of indoor chemicals, and whose activities (e.g., cooking, cleaning, smoking) can lead to extremely high pollutant concentrations. As we begin to use increasingly sensitive and selective instrumentation indoors, we are learning more about chemistry in this relatively understudied environment.

Emission Rates of Multiple Air Pollutants Generated from Chinese Residential Cooking

Household air pollution generated from cooking is severe, especially for Chinese-style cooking. We measured the emission rates of multiple air pollutants including fine particles (PM_2.5), ultrafine particles (UFPs), and volatile organic compounds (VOCs, including formaldehyde, benzene, and toluene) that were generated from typical Chinese cooking in a residential kitchen. The experiment was designed through five-factor and five-level orthogonal testing. The five key factors were cooking method, ingredient weight, type of meat, type of oil, and meat/vegetable ratio. The measured emission rates (mean value ± standard deviation) of PM_2.5, UFPs, formaldehyde, total volatile organic compounds (TVOCs), benzene, and toluene were 2.056 ± 3.034 mg/min, 9.102 ± 6.909 × 10¹² #/min, 1.273 ± 0.736 mg/min, 1.349 ± 1.376 mg/min, 0.074 ± 0.039 mg/min, and 0.004 ± 0.004 mg/min. Cooking method was the most influencing factor for the emission rates of PM_2.5, UFPs, formaldehyde, TVOCs, and benzene but not for toluene. Meanwhile, the emission rate of PM_2.5 was also significantly influenced by ingredient weight, type of meat, and meat/vegetable ratio. Exhausting the range hood decreased the emission rates by approximately 58%, with a corresponding air change rate of 21.38/h for the kitchen room.

Quantifying fine particle emission events from time-resolved measurements: Method description and application to 18 California low-income apartments

PM_2.5 exposure is associated with significant health risk. Exposures in homes derive from both outdoor and indoor sources, with emissions occurring primarily in discrete events. Data on emission event magnitudes and schedules are needed to support simulation-based studies of exposures and mitigations. This study applied an identification and characterization algorithm to quantify time-resolved PM_2.5 emission events from data collected during 224 days of monitoring in 18 California apartments with low-income residents. We identified and characterized 836 distinct events with median and mean values of 12 and 30 mg emitted mass, 16 and 23 minutes emission duration, 37 and 103 mg/h emission rates, and pseudo-first-order decay rates of 1.3 and 2.0/h. Mean event-averaged concentrations calculated using the determined event characteristics agreed to within 6% of measured values for 14 of the apartments. There were variations in event schedules and emitted mass across homes, with few events overnight and most emissions occurring during late afternoons and evenings. Event characteristics were similar during weekdays and weekends. Emitted mass was positively correlated with number of residents (Spearman coefficient, ρ=.10), bedrooms (ρ=.08), house volume (ρ=.29), and indoor-outdoor CO₂ difference (ρ=.27). The event schedules can be used in probabilistic modeling of PM_2.5 in low-income apartments.

The influence of lifestyle on airborne particle surface area doses received by different Western populations

In the present study, the daily dose in terms of particle surface area received by citizens living in five cities in Western countries, characterized by different lifestyle, culture, climate and built-up environment, was evaluated and compared. For this purpose, the exposure to sub-micron particle concentration levels of the population living in Barcelona (Spain), Cassino (Italy), Guilford (United Kingdom), Lund (Sweden), and Brisbane (Australia) was measured through a direct exposure assessment approach. In particular, measurements of the exposure at a personal scale were performed by volunteers (15 per each population) that used a personal particle counter for different days in order to obtain exposure data in microenvironments/activities they resided/performed. Non-smoking volunteers performing non-industrial jobs were considered in the study. Particle concentration data allowed obtaining the exposure of the population living in each city. Such data were combined in a Monte Carlo method with the time activity pattern data characteristics of each population and inhalation rate to obtain the most probable daily dose in term of particle surface area as a function of the population gender, age, and nationality. The highest daily dose was estimated for citizens living in Cassino and Guilford (>1000 mm²), whereas the lowest value was recognized for Lund citizens (around 100 mm²). Indoor air quality, and in particular cooking and eating activities, was recognized as the main influencing factor in terms of exposure (and thus dose) of the population: then confirming that lifestyle (e.g. time spent in cooking activities) strongly affect the daily dose of the population. On the contrary, a minor or negligible contribution of the outdoor microenvironments was documented.

Emission of volatile organic compounds and production of secondary organic aerosol from stir-frying spices

Cooking is an important source of volatile organic compounds (VOCs) and a potential source of secondary organic aerosol (SOA) both indoors and outdoors. In this study, VOC emissions from heating corn oil and stir-frying spices (i.e. garlic, ginger, myrcia and zanthoxylum piperitum (Sichuan pepper)) were characterized using an on-line membrane inlet vacuum ultraviolet single-photon ionization time-of-flight mass spectrometer (VUV-SPI-TOFMS). VOC emissions from heating corn oil were dominated by aldehydes, which were enhanced by factors of one order of magnitude when stir-frying spices. Stir-frying any of the spices studied generated large amounts of methylpyrrole (m/z 81). In addition, stir-frying garlic produced abundant dihydrohydroxymaltol (m/z 144) and diallyldisulfide (DADS) (m/z 146), while stir-frying ginger, myrcia and zanthoxylum piperitum produced abundant monoterpenes (m/z 136) and terpenoids (m/z 152, 154). SOA formed from emissions of stir-frying spices through reactions with excess ozone in a flow reactor as well as primary organic aerosol (POA) emissions were characterized using a scanning mobility particle sizer (SMPS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS). Stir-frying garlic and ginger generated similar POA concentrations to those from heating corn oil while stir-frying myrcia and zanthoxylum piperitum generated double the amount of emissions. No SOA was observed from stir-frying garlic and ginger. The rates of SOA production from stir-frying myrcia and zanthoxylum piperitum were 1.8μgmin^-1g_spice^-1 and 8.7μgmin^-1g_spice^-1, equivalent to 13.4% and 53.1% of their own POA emission rates, respectively. Therefore, the contribution of stir-frying spices to ambient organic aerosol levels is likely dominated by POA. The rates of total terpene emission from stir-frying myrcia and zanthoxylum piperitum were estimated to be 5.1μgmin^-1g_spice^-1 and 24.9μgmin^-1g_spice^-1, respectively. Our results suggest that stir-frying spices could be an important source of terpenes in indoor environments in Hong Kong, at least during cooking.

Ultrafine Particle Production from the Ozonolysis of Personal Care Products

Personal care products (PCP) might be a source of ultrafine particle exposure for users owing to the reaction of ozone with terpene ingredients. The near-person emissions associated with PCP may contribute to exposures that would not be properly accounted for with indoor microenvironmental measurements. To better understand this issue, screening experiments were conducted with 91 PCP to detect the occurrence of ultrafine particle production from exposure to common indoor levels of ozone (23 ± 2 ppb). Twelve products generated measurable particle emissions; quantification experiments were performed for these to determine total particle production and peak particle production rate. A high-resolution, small volume reaction chamber was used with a heated sample plate to simulate conditions found in the human thermal plume. Ten of the quantified PCP exhibited total emissions of less than 10⁹ particles, suggesting that they may not be significant sources of total ultrafine particle exposure. Two samples, a tea tree oil-based scalp treatment and a white lavender body lotion, exhibited relatively elevated peak particle emission rates, 6.2 × 10⁷ min^-1 and 2.0 × 10⁷ min^-1, respectively. The use of such products in the presence of significant ozone levels might materially influence personal exposure to ultrafine particles.

Growth of organic films on indoor surfaces

We present a model for the growth of organic films on impermeable indoor surfaces. The model couples transport through a gas-side boundary layer adjacent to the surface with equilibrium partitioning of semivolatile organic compounds (SVOCs) between the gas phase and the surface film. Model predictions indicate that film growth would primarily be influenced by the gas-phase concentration of SVOCs with octanol-air partitioning (K_oa ) values in the approximate range 10≤log K_oa ≤13. Within the relevant range, SVOCs with lower values will equilibrate with the surface film more rapidly. Over time, the film becomes relatively enriched in species with higher log K_oa values, while the proportion of gas-phase SVOCs not in equilibrium with the film decreases. Given stable airborne SVOC concentrations, films grow at faster rates initially and then subsequently diminish to an almost steady growth rate. Once an SVOC is equilibrated with the film, its mass per unit film volume remains constant, while its mass per unit area increases in proportion to overall film thickness. The predictions of the conceptual model and its mathematical embodiment are generally consistent with results reported in the peer-reviewed literature.

Review of factors impacting emission/concentration of cooking generated particulate matter

Studies have shown that exposure to particulate matter (PM) emitted while cooking is related to adverse human health effects. The level of PM emissions during cooking varies with several factors. This study reviewed controlled studies available in the cooking PM emissions literature, and found that cooking method, type and quality of the energy (heating) source, burner size, cooking pan, cooking oil, food, additives, source surface area, cooking temperature, ventilation and position of the cooking pan on the stove are influential factors affecting cooking PM emission rates and resulting concentrations. Opportunities to reduce indoor PM concentrations during cooking are proposed. Minor changes in cooking habits and manner might result in a substantial reduction in the cook's exposure to the cooking PM. Finally, the need for additional studies is discussed.

Size segregated PM and its chemical composition emitted from heated corn oil

Characterization of the airborne particulate matter (PM) emitted from cooking components including cooking oil, and additives like salt has not been carefully investigated. This study provides new data on the concentration, composition, and emission rates/fluxes of PM (less than 3.3µm) generated during heating corn oil and corn oil with added table salt. The concept of emission flux was employed to estimate the emission rates in this study. A statistically significant reduction of 47.6% (P<0.05) in the total PM emission rate and emission flux were observed when salt was added to the heated corn oil (5.15×10¹mgmin^-1) compared to the pure oil (9.83×10¹mgmin^-1). The OC emission rate decreased 61.3% (P<0.05) when salt was added to the corn oil (2.35×10¹mgmin^-1) compared to the pure corn oil (5.83×10¹mgmin^-1). With the salt, the total EC emission rate was 6.99×10^-1mgmin^-1, a 62.7% reduction in EC emission compared to pure corn oil (1.88mgmin^-1). These results suggest that table salt can be added to the corn oil prior to frying to reduce exposure to cooking generated PM.

Quantifying trace elements in the emitted particulate matter during cooking and health risk assessment

Particulate matter (PM) measurements were conducted during heating corn oil, heating corn oil mixed with the table salt and heating low fat ground beef meat using a PTFE-coated aluminum pan on an electric stove with low ventilation. The main objectives of this study were to measure the size segregated mass concentrations, emission rates, and fluxes of 24 trace elements emitted during heating cooking oil or oil with salt and cooking meat. Health risk assessments were performed based on the resulting exposure to trace elements from such cooking activities. The most abundant elements (significantly different from zero) were Ba (24.4 ug m^-3) during grilling meat and Ti during heating oil with salt (24.4 ug m^-3). The health assessment indicates that the cooking with an electric stove with poor ventilation leading to chronic exposures may pose the risk of significant adverse health effects. Carcinogenic risk exceeded the acceptable level (target cancer risk 1 × 10^-6, US EPA 2015) by four orders of magnitude, while non-carcinogenic risk exceeded the safe level (target HQ = 1, US EPA 2015) by a factor of 5-20. Cr and Co were the primary contributors to the highest carcinogenic and non-carcinogenic risks, respectively.

Airborne particle emission of a commercial 3D printer: the effect of filament material and printing temperature

The knowledge of exposure to the airborne particle emitted from three-dimensional (3D) printing activities is becoming a crucial issue due to the relevant spreading of such devices in recent years. To this end, a low-cost desktop 3D printer based on fused deposition modeling (FDM) principle was used. Particle number, alveolar-deposited surface area, and mass concentrations were measured continuously during printing processes to evaluate particle emission rates (ERs) and factors. Particle number distribution measurements were also performed to characterize the size of the emitted particles. Ten different materials and different extrusion temperatures were considered in the survey. Results showed that all the investigated materials emit particles in the ultrafine range (with a mode in the 10-30-nm range), whereas no emission of super-micron particles was detected for all the materials under investigation. The emission was affected strongly by the extrusion temperature. In fact, the ERs increase as the extrusion temperature increases. Emission rates up to 1×10¹²  particles min^-1 were calculated. Such high ERs were estimated to cause large alveolar surface area dose in workers when 3D activities run. In fact, a 40-min-long 3D printing was found to cause doses up to 200 mm² .

Desorption of SVOCs from Heated Surfaces in the Form of Ultrafine Particles

Ultrafine particles (UFP) produced by electric heating of stoves and metal cooking pans, absent food, have been hypothesized to be created from a surface film of semivolatile organic compounds (SVOCs) sorbed from the surrounding air. This study tests that hypothesis by size-resolved measurements extending the lower range of the UFP studied from 10 to 2.3 nm, and including other surfaces (glass, aluminum, and porcelain). Heating glass Petri dishes or squares of aluminum foil to about 350-400 °C for 4-6 min removed all sorbed organic substances completely. Subsequent exposure of these "clean" Petri dishes and foil squares to indoor air in two different residences for successively longer periods (1 h to 281 days), followed by heating the materials for 4-6 min, indicated a strong relationship of the number, size distribution, and mass of the UFP to the time exposed. Estimates of the accumulation rate of SVOCs on surfaces were similar to those in studies of organic film buildup on indoor windows. Transfer of skin oils by touching the glass or foil surfaces, or after washing the glass surface with detergent and bare hands, was also observed, with measured particle production comparable with that produced by long-term exposure to indoor air.

Fine and ultrafine particle exposures on 73 trips by car to 65 non-smoking restaurants in the San Francisco Bay Area

A number of studies indicate cooking is a major source of exposure to particulate matter, but few studies have measured indoor air pollution in restaurants, where cooking predominates. We made 73 visits by car to 65 different non-smoking restaurants in 10 Northern California towns while carrying portable continuous monitors that unobtrusively measured ultrafine (down to 10 nm) and fine (PM_2.5 ) particles to characterize indoor restaurant exposures, comparing them with exposures in the car. The mean ultrafine number concentrations in the restaurants on dinner visits averaging 1.4 h was 71 600 particles/cm³ , or 4.3 times the mean concentration on car trips, and 12.3 times the mean background concentration in the residence. Restaurants that cooked dinner in the same room as the patrons had higher ultrafine concentrations than restaurants with separate kitchens. Restaurant PM_2.5 mass concentrations averaged 36.3 μg/m³ , ranging from 1.5 to 454 μg/m³ , but were relatively low on most visits: 43% of the indoor means were below 10 μg/m³ and 66% were below 20 μg/m³ , with 5.5% above 100 μg/m³ . Exposure to fine and ultrafine particles when visiting a restaurant exceeded the exposure a person received while traveling by car to and from the restaurant.

Size-Resolved Source Emission Rates of Indoor Ultrafine Particles Considering Coagulation

Indoor ultrafine particles (UFP, <100 nm) released from combustion and consumer products lead to elevated human exposure to UFP. UFP emitted from the sources undergo aerosol transformation processes such as coagulation and deposition. The coagulation effect can be significant during the source emission due to high concentration and high mobility of nanosize particles. However, few studies have estimated size-resolved UFP source emission strengths while considering coagulation in their theoretical and experimental research work. The primary objective of this study is to characterize UFP source strength by considering coagulation in addition to other indoor processes (i.e., deposition and ventilation) in a realistic setting. A secondary objective is to test a hypothesis that size-resolved UFP source emission rates are unimodal and log-normally distributed for three common indoor UFP sources: an electric stove, a natural gas burner, and a paraffin wax candle. Experimental investigations were performed in a full-scale test building. Size- and time-resolved concentrations of UFP ranging from 2 to 100 nm were monitored using a scanning mobility particle sizer (SMPS). Based on the temporal evolution of the particle size distribution during the source emission period, the size-dependent source emission rate was determined using a material-balance modeling approach. The results indicate that, for a given UFP source, the source strength varies with particle size and source type. The analytical model assuming a log-normally distributed source emission rate could predict the temporal evolution of the particle size distribution with reasonable accuracy for the gas stove and the candle. Including the effect of coagulation was found to increase the estimates of source strengths by up to a factor of 8. This result implies that previous studies on indoor UFP source strengths considering only deposition and ventilation might have largely underestimated the true values of UFP source strengths, especially for combustion due to the natural gas stove and the candle.

Emission of particulate matter from a desktop three-dimensional (3D) printer

Desktop three-dimensional (3D) printers are becoming commonplace in business offices, public libraries, university labs and classrooms, and even private homes; however, these settings are generally not designed for exposure control. Prior experience with a variety of office equipment devices such as laser printers that emit ultrafine particles (UFP) suggests the need to characterize 3D printer emissions to enable reliable risk assessment. The aim of this study was to examine factors that influence particulate emissions from 3D printers and characterize their physical properties to inform risk assessment. Emissions were evaluated in a 0.5-m(3) chamber and in a small room (32.7 m(3)) using real-time instrumentation to measure particle number, size distribution, mass, and surface area. Factors evaluated included filament composition and color, as well as the manufacturer-provided printer emissions control technologies while printing an object. Filament type significantly influenced emissions, with acrylonitrile butadiene styrene (ABS) emitting larger particles than polylactic acid (PLA), which may have been the result of agglomeration. Geometric mean particle sizes and total particle (TP) number and mass emissions differed significantly among colors of a given filament type. Use of a cover on the printer reduced TP emissions by a factor of 2. Lung deposition calculations indicated a threefold higher PLA particle deposition in alveoli compared to ABS. Desktop 3D printers emit high levels of UFP, which are released into indoor environments where adequate ventilation may not be present to control emissions. Emissions in nonindustrial settings need to be reduced through the use of a hierarchy of controls, beginning with device design, followed by engineering controls (ventilation) and administrative controls such as choice of filament composition and color.