Coarse particulate matter and airborne endotoxin within wood stove homes

Emissions from indoor biomass burning are a major public health concern in developing areas of the world. Less is known about indoor air quality, particularly airborne endotoxin, in homes burning biomass fuel in residential wood stoves in higher income countries. A filter‐based sampler was used to evaluate wintertime indoor coarse particulate matter (PM_10‐2.5) and airborne endotoxin (EU/m³, EU/mg) concentrations in 50 homes using wood stoves as their primary source of heat in western Montana. We investigated number of residents, number of pets, dampness (humidity), and frequency of wood stove usage as potential predictors of indoor airborne endotoxin concentrations. Two 48‐h sampling events per home revealed a mean winter PM_10‐2.5 concentration (± s.d.) of 12.9 (± 8.6) μg/m³, while PM_2.5 concentrations averaged 32.3 (± 32.6) μg/m³. Endotoxin concentrations measured from PM_10‐2.5 filter samples were 9.2 (± 12.4) EU/m³ and 1010 (± 1524) EU/mg. PM_10‐2.5 and PM_2.5 were significantly correlated in wood stove homes (r = 0.36, P < 0.05). The presence of pets in the homes was associated with PM_10‐2.5 but not with endotoxin concentrations. Importantly, none of the other measured home characteristics was a strong predictor of airborne endotoxin, including frequency of residential wood stove usage.     

Personal exposure to PM2.5 in Chinese rural households in the Yangtze River Delta

High levels of PM_2.5 exposure and associated health risks are of great concern in rural China. For this study, we used portable PM_2.5 monitors for monitoring concentrations online, recorded personal time‐activity patterns, and analyzed the contribution from different microenvironments in rural areas of the Yangtze River Delta, China. The daily exposure levels of rural participants were 66 μg/m³ (SD 40) in winter and 65 μg/m³ (SD 16) in summer. Indoor exposure levels were usually higher than outdoor levels. The exposure levels during cooking in rural kitchens were 140 μg/m³ (SD 116) in winter and 121 μg/m³ (SD 70) in summer, the highest in all microenvironments. Winter and summer values were 252 μg/m³ (SD 103) and 204 μg/m³ (SD 105), respectively, for rural people using biomass for fuel, much higher than those for rural people using LPG and electricity. By combining PM_2.5concentrations and time spent in different microenvironments, we found that 92% (winter) and 85% (summer) of personal exposure to PM_2.5in rural areas was attributable to indoor microenvironments, of which kitchens accounted for 24% and 27%, respectively. Consequently, more effective policies and measures are needed to replace biomass fuel with LPG or electricity, which would benefit the health of the rural population in China.     

Controlled experiments measuring personal exposure to PM2.5 in close proximity to cigarette smoking

Few measurements of exposure to secondhand smoke (SHS) in close proximity to a smoker are available. Recent health studies have demonstrated an association between acute (<2 h) exposures to high concentrations of SHS and increased risk of cardiovascular and respiratory disease. We performed 15 experiments inside naturally ventilated homes and 16 in outdoor locations, each with 2–4 non‐smokers sitting near a cigarette smoker. The smoker's and non‐smokers' real‐time exposures to PM_2.5 from SHS were measured by using TSI SidePak monitors to sample their breathing zones. In 87% of the residential indoor experiments, the smoker received the highest average exposure to SHS, with PM_2.5 concentrations ranging from 50–630 μg/m³. During the active smoking period, individual non‐smokers sitting within approximately 1 m of a smoker had average SHS exposures ranging from negligible up to >160 μg/m³ of PM_2.5. The average incremental exposure of the non‐smokers was higher indoors (42 μg/m³, n = 35) than outdoors (29 μg/m³, n = 47), but the overall indoor and outdoor frequency distributions were similar. The 10‐s PM_2.5 averages during the smoking periods showed great variability, with multiple high concentrations of short duration (microplumes) both indoors and outdoors.     

Airborne endotoxin concentrations in indoor and outdoor particulate matter and their predictors in an urban city

Endotoxins are an important biological component of particulate matter and have been associated with adverse effects on human health. There have been some recent studies on airborne endotoxin concentrations. We collected fine (PM_2.5) and coarse (PM_10‐2.5) particulate matter twice on weekdays and weekends each for 48 hour, inside and outside 55 homes in an urban city in Japan. Endotoxin concentrations in both fractions were measured using the kinetic Limulus Amebocyte Lysate assay. The relationships between endotoxin concentrations and household characteristics were evaluated for each fraction. Both indoor and outdoor endotoxin concentrations were higher in PM_2.5 than in PM_10‐2.5. In both PM_2.5 and PM_10‐2.5, indoor endotoxin concentrations were higher than outdoor concentrations, and the indoor endotoxin concentrations significantly correlated with outdoor concentrations in each fraction (R²=0.458 and 0.198, respectively). Indoor endotoxin concentrations in PM_2.5 were significantly higher in homes with tatami or carpet flooring and in homes with pets, and lower in homes that used air purifiers. Indoor endotoxin concentrations in PM_10‐2.5 were significantly higher in homes with two or more children and homes with tatami or carpet flooring. These results showed that the indoor endotoxin concentrations were associated with the household characteristics in addition to outdoor endotoxin concentrations.     

Seasonal variability in environmental tobacco smoke exposure in public housing developments

The risk of tobacco smoking and second‐hand smoke (SHS) exposure combined are the leading contributors to disease burden in high‐income countries. Recent studies and policies are focusing on reducing exposure to SHS in multiunit housing (MUH), especially public housing. We examined seasonal patterns of SHS levels within indoor common areas located on Boston Housing Authority (BHA) properties. We measured weekly integrated and continuous fine particulate matter (PM_2.5) and passive airborne nicotine in six buildings of varying building and occupant characteristics in summer 2012 and winter 2013. The average weekly indoor PM_2.5 concentration across all six developments was 9.2 μg/m³, higher during winter monitoring period (10.3 μg/m³) compared with summer (8.0 μg/m³). Airborne nicotine concentrations ranged from no detection to about 5000 ng/m³ (mean 311 ng/m³). Nicotine levels were significantly higher in the winter compared with summer (620 vs. 85 ng/m³; 95% CI: 72–998). Smoking‐related exposures within Boston public housing vary by season, building types, and resident smoking policy. Our results represent exposure disparities that may contribute to health disparities in low‐income communities and highlight the potential importance of efforts to mitigate SHS exposures during winter when outdoor–indoor exchange rates are low and smokers may tend to stay indoors. Our findings support the use of smoke‐free policy as an effective tool to eliminate SHS exposure and protect non‐smokers, especially residents of MUH.     

Exposure to household air pollution from biomass cookstoves and blood pressure among women in rural Honduras: A cross‐sectional study

Growing evidence links household air pollution exposure from biomass cookstoves with elevated blood pressure. We assessed cross‐sectional associations of 24‐hour mean concentrations of personal and kitchen fine particulate matter (PM_2.5), black carbon (BC), and stove type with blood pressure, adjusting for confounders, among 147 women using traditional or cleaner‐burning Justa stoves in Honduras. We investigated effect modification by age and body mass index. Traditional stove users had mean (standard deviation) personal and kitchen 24‐hour PM_2.5 concentrations of 126 μg/m³ (77) and 360 μg/m³ (374), while Justa stove users’ exposures were 66 μg/m³ (38) and 137 μg/m³ (194), respectively. BC concentrations were similarly lower among Justa stove users. Adjusted mean systolic blood pressure was 2.5 mm Hg higher (95% CI, 0.7‐4.3) per unit increase in natural log‐transformed kitchen PM_2.5 concentration; results were stronger among women of 40 years or older (5.2 mm Hg increase, 95% CI, 2.3‐8.1). Adjusted odds of borderline high and high blood pressure (categorized) were also elevated (odds ratio = 1.5, 95% CI, 1.0‐2.3). Some results included null values and are suggestive. Results suggest that reduced household air pollution, even when concentrations exceed air quality guidelines, may help lower cardiovascular disease risk, particularly among older subgroups.     

Particle characterization in retail environments: concentrations,sources, and removal mechanisms

Particles in retail environments can have consequences for the occupational exposures of retail workers and customers, as well as the energy costs associated with ventilation and filtration. Little is known about particle characteristics in retail environments. We measured indoor and outdoor mass concentrations of PM₁₀ and PM_2.5, number concentrations of submicron particles (0.02–1 μm), size‐resolved 0.3–10 μm particles, as well as ventilation rates in 14 retail stores during 24 site visits in Pennsylvania and Texas. Overall, the results were generally suggestive of relatively clean environments when compared to investigations of other building types and ambient/occupational regulatory limits. PM₁₀ and PM_2.5 concentrations (mean ± s.d.) were 20 ± 14 and 11 ± 10 μg/m³, respectively, with indoor‐to‐outdoor ratios of 1.0 ± 0.7 and 0.88 ± 1.0. Mean submicron particle concentrations were 7220 ± 7500 particles/cm³ with an indoor‐to‐outdoor ratio of 1.18 ± 1.30. The median contribution to PM₁₀ and PM_2.5 concentrations from indoor sources (vs. outdoors) was 83% and 53%, respectively. There were no significant correlations between measured ventilation rates and particle concentrations of any size. When examining options to lower PM_2.5 concentrations below regulatory limits, the required changes to ventilation and filtration efficiency were site specific and depended on the indoor and outdoor concentration, emission rate, and infiltration level.     

Chimney stoves modestly improved Indoor Air Quality measurements compared with traditional open fire stoves: results from a small‐scale intervention study in rural Peru

Nearly half of the world's population depends on biomass fuels to meet domestic energy needs, producing high levels of pollutants responsible for substantial morbidity and mortality. We compare carbon monoxide (CO) and particulate matter (PM_2.5) exposures and kitchen concentrations in households with study‐promoted intervention (OPTIMA‐improved stoves and control stoves) in San Marcos Province, Cajamarca Region, Peru. We determined 48‐h indoor air concentration levels of CO and PM_2.5 in 93 kitchen environments and personal exposure, after OPTIMA‐improved stoves had been installed for an average of 7 months. PM_2.5 and CO measurements did not differ significantly between OPTIMA‐improved stoves and control stoves. Although not statistically significant, a post hoc stratification of OPTIMA‐improved stoves by level of performance revealed mean PM_2.5 and CO levels of fully functional OPTIMA‐improved stoves were 28% lower (n = 20, PM_2.5, 136 μg/m³ 95% CI 54–217) and 45% lower (n = 25, CO, 3.2 ppm, 95% CI 1.5–4.9) in the kitchen environment compared with the control stoves (n = 34, PM_2.5, 189 μg/m³, 95% CI 116–261; n = 44, CO, 5.8 ppm, 95% CI 3.3–8.2). Likewise, although not statistically significant, personal exposures for OPTIMA‐improved stoves were 43% and 17% lower for PM_2.5 (n = 23) and CO (n = 25), respectively. Stove maintenance and functionality level are factors worthy of consideration for future evaluations of stove interventions.     

Effectiveness of portable HEPA air cleaners on reducing indoor endotoxin,PM10, and coarse particulate matter in an agricultural cohort of children with asthma: A randomized intervention trial

We conducted a randomized trial of portable HEPA air cleaners in the homes of children age 6–12 years with asthma in the Yakima Valley, Washington. All families received asthma education while intervention families also received two HEPA cleaners (child's bedroom, living room). We collected 14-day integrated samples of endotoxin in settled dust and PM₁₀ and PM_10-2.5 in the air of the children's bedrooms at baseline and one-year follow-up, and used linear regression to compare follow-up levels, adjusting for baseline. Seventy-one families (36 HEPA, 35 control) completed the study. Baseline geometric mean (GSD) endotoxin loadings were 1565 (6.3) EU/m² and 2110 (4.9) EU/m², respectively, in HEPA vs. control homes while PM₁₀ and PM_10-2.5 were 22.5 (1.9) μg/m³ and 9.5 (2.9) μg/m³, respectively, in HEPA homes, and 19.8 (1.8) μg/m³ and 7.7 (2.0) μg/m³, respectively, in control homes. At follow-up, HEPA families had 46% lower (95% CI, 31%–57%) PM₁₀ on average than control families, consistent with prior studies. In the best-fit heterogeneous slopes model, HEPA families had 49% (95% CI, 6%–110%) and 89% lower (95% CI, 28%–177%) PM_10-2.5 at follow-up, respectively, at 50th and 75th percentile baseline concentrations. Endotoxin loadings did not differ significantly at follow-up (4% lower, HEPA homes; 95% CI, −87% to 50%).     

Unexpected increase in indoor pollutants after the introduction of a smoke‐free policy in a correctional center

Correctional centers (prisons) are one of the few non‐residential indoor environments where smoking is still permitted. However, few studies have investigated indoor air quality (IAQ) in these locations. We quantified the level of inmate and staff exposure to secondhand smoke, including particle number (PN) count, and we assessed the impact of the smoking ban on IAQ. We performed measurements of indoor and outdoor PM_2.5 and PN concentrations, personal PN exposure levels, volatile organic compounds (VOCs), and nicotine both before and after a complete indoor smoking ban in an Australian maximum security prison. Results show that the indoor 24‐h average PM_2.5 concentrations ranged from 6 (±1) μg/m³ to 17 (±3) μg/m³ pre‐ban. The post‐ban levels ranged from 7 (±2) μg/m³ to 71 (±43) μg/m³. While PM_2.5 concentrations decreased in one unit post‐ban, they increased in the other two units. Similar post‐ban increases were also observed in levels of PN and VOCs. We describe an unexpected increase of indoor pollutants following a total indoor smoking ban in a prison that was reflected across multiple pollutants that are markers of smoking. We hypothesise that clandestine post‐ban smoking among inmates may have been the predominant cause.     

Impact of neighborhood biomass cooking patterns on episodic high indoor particulate matter concentrations in clean fuel homes in Dhaka,Bangladesh

Exposure to particulate matter (PM_2.5) from the burning of biomass is associated with increased risk of respiratory disease. In Dhaka, Bangladesh, households that do not burn biomass often still experience high concentrations of PM_2.5, but the sources remain unexplained. We characterized the diurnal variation in the concentrations of PM_2.5 in 257 households and compared the risk of experiencing high PM_2.5 concentrations in biomass and non‐biomass users. Indoor PM_2.5 concentrations were estimated every minute over 24 h once a month from April 2009 through April 2010. We found that households that used gas or electricity experienced PM_2.5 concentrations exceeding 1000 μg/m³ for a mean of 35 min within a 24‐h period compared with 66 min in biomass‐burning households. In both households that used biomass and those that had no obvious source of particulate matter, the probability of PM_2.5 exceeding 1000 μg/m³ were highest during distinct morning, afternoon, and evening periods. In such densely populated settings, indoor pollution in clean fuel households may be determined by biomass used by neighbors, with the highest risk of exposure occurring during cooking periods. Community interventions to reduce biomass use may reduce exposure to high concentrations of PM_2.5 in both biomass and non‐biomass using households.     

Determinants of house dust,endotoxin, and β‐(1→3)‐D‐glucan in homes of Danish children

Little is known about the geographic variation and determinants of bacterial endotoxin and β ‐(1,3)‐d ‐glucan in Danish house dust. In a population of 317 children, we: (i) described loads and concentrations of floor dust, endotoxin, and β‐(1→3)‐d ‐glucan and (ii) their correlations and (iii) assessed their determinants; (iv) Finally, we compared our findings with previous European studies. Bedroom floor dust was analyzed for endotoxin content by the kinetic limulus amoebocyte lysate assay and for β‐(1→3)‐d ‐glucan by the inhibition enzyme immunoassay. The parents answered questions regarding potential determinants. We found: geometric means (geometric standard deviations) 186 mg/m² (4.3) for dust; 5.46 × 10³EU/m² (8.0) and 31.1 × 10³EU/g (2.6) for endotoxin; and 142 μg/m² (14.3) and 0.71 × 10³ μg/g (7.3) for β‐(1→3)‐d ‐glucan. High correlations (r > 0.75) were found between floor dust and endotoxin and β‐(1→3)‐d ‐glucan loads, while endotoxin and β‐(1→3)‐d ‐glucan concentrations were moderately correlated (r = 0.36–0.41) with the dust load. Having a carpet was positively associated with dust load and with endotoxin and β‐(1→3)‐d ‐glucan concentrations. Pet keeping, dwelling type, and dwelling location were determinants of endotoxin concentrations. No other determinants were associated with β‐(1→3)‐d ‐glucan concentrations. Compared with other European studies, we found lower β‐(1→3)‐d ‐glucan loads and concentrations but higher endotoxin loads and concentrations suggesting a geographically determined different composition of Danish floor dust compared with other European regions.     

Kerosene lighting contributes to household air pollution in rural Uganda

The literature on the contribution of kerosene lighting to indoor air particulate concentrations is sparse. In rural Uganda, kitchens are almost universally located outside the main home, and kerosene is often used for lighting. In this study, we obtained longitudinal measures of particulate matter 2.5 microns or smaller in size (PM_2.5) from living rooms and kitchens of 88 households in rural Uganda. Linear mixed‐effects models with a random intercept for household were used to test the hypotheses that primary reported lighting source and kitchen location (indoor vs outdoor) are associated with PM_2.5 levels. During initial testing, households reported using the following sources of lighting: open‐wick kerosene (19.3%), hurricane kerosene (45.5%), battery‐powered (33.0%), and solar (1.1%) lamps. During follow‐up testing, these proportions changed to 29.5%, 35.2%, 18.2%, and 9.1%, respectively. Average ambient, living room, and kitchen PM_2.5 levels were 20.2, 35.2, and 270.0 μg/m³. Living rooms using open‐wick kerosene lamps had the highest PM_2.5 levels (55.3 μg/m³) compared to those using solar lighting (19.4 μg/m³; open wick vs solar, P=.01); 27.6% of homes using open‐wick kerosene lamps met World Health Organization indoor air quality standards compared to 75.0% in homes using solar lighting.     

Developing a predictive model for fine particulate matter concentrations in low socio‐economic households in Durban,South Africa

In low‐resource settings, there is a need to develop models that can address contributions of household and outdoor sources to population exposures. The aim of the study was to model indoor PM_2.5 using household characteristics, activities, and outdoor sources. Households belonging to participants in the Mother and Child in the Environment (MACE) birth cohort, in Durban, South Africa, were randomly selected. A structured walk‐through identified variables likely to generate PM_2.5. MiniVol samplers were used to monitor PM_2.5 for a period of 24 hours, followed by a post‐activity questionnaire. Factor analysis was used as a variable reduction tool. Levels of PM_2.5 in the south were higher than in the north of the city (P < .05); crowding and dwelling type, household emissions (incense, candles, cooking), and household smoking practices were factors associated with an increase in PM_2.5 levels (P < .05), while room magnitude and natural ventilation factors were associated with a decrease in the PM_2.5 levels (P < .05). A reasonably robust PM_2.5 predictive model was obtained with model R² of 50%. Recognizing the challenges in characterizing exposure in environmental epidemiological studies, particularly in resource‐constrained settings, modeling provides an opportunity to reasonably estimate indoor pollutant levels in unmeasured homes.     

Classroom ventilation and indoor air quality—results from the FRESH intervention study

Inadequate ventilation of classrooms may lead to increased concentrations of pollutants generated indoors in schools. The FRESH study, on the effects of increased classroom ventilation on indoor air quality, was performed in 18 naturally ventilated classrooms of 17 primary schools in the Netherlands during the heating seasons of 2010–2012. In 12 classrooms, ventilation was increased to targeted CO₂ concentrations of 800 or 1200 ppm, using a temporary CO₂ controlled mechanical ventilation system. Six classrooms were included as controls. In each classroom, data on endotoxin, β(1,3)‐glucans, and particles with diameters of <10 μm (PM₁₀) and <2.5 μm (PM_2.5) and nitrogen dioxide (NO₂) were collected during three consecutive weeks. Associations between the intervention and these measured indoor air pollution levels were assessed using mixed models, with random classroom effects. The intervention lowered endotoxin and β(1,3)‐glucan levels and PM₁₀ concentrations significantly. PM₁₀ for instance was reduced by 25 μg/m³ (95% confidence interval 13–38 μg/m³) from 54 μg/m³ at maximum ventilation rate. No significant differences were found between the two ventilation settings. Concentrations of PM_2.5 and NO₂ were not affected by the intervention. Our results provide evidence that increasing classroom ventilation is effective in decreasing the concentrations of some indoor‐generated pollutants.     

Chemical characterization of PM₁₀ and PM₂.₅ mass concentrations emitted by heterogeneous traffic

In this paper, the chemical characterization of PM₁₀ and PM_2.5 mass concentrations emitted by heterogeneous traffic in Chennai city during monsoon, winter and summer seasons were analysed. The 24-h averages of PM₁₀ and PM_2.5 mass concentrations, showed higher concentrations during the winter season (PM₁₀ = 98 μg/m³; PM_2.5 = 74 μg/m³) followed by the monsoon (PM₁₀ = 87 μg/m³; PM_2.5 = 56 μg/m³) and summer (PM₁₀ = 77 μg/m³; PM_2.5 = 67 μg/m³) seasons. The assessment of 24-h average PM₁₀ and PM_2.5 concentrations was indicated as violation of the world health organization (WHO standard for PM₁₀ = 50 μg/m³ and PM_2.5 = 25 μg/m³) and Indian national ambient air quality standards (NAAQS for PM₁₀ = 100 μg/m³ and PM_2.5 = 60 μg/m³).The chemicals characterization of PM₁₀ and PM_2.5 samples (22 samples) for each season were made for water soluble ions using Ion Chromatography (IC) and trace metals by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) instrument. Results showed the dominance of crustal elements (Ca, Mg, Al, Fe and K), followed by marine aerosols (Na and K) and trace elements (Zn, Ba, Be, Ca, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, Sr and Te) emitted from road traffic in both PM₁₀ and PM_2.5 mass. The ionic species concentration in PM₁₀ and PM_2.5 mass consists of 47-65% of anions and 35-53% of cations with dominance of SO₄²⁻ ions. Comparison of the metallic and ionic species in PM₁₀ and PM_2.5 mass indicated the contributions from sea and crustal soil emissions to the coarse particles and traffic emissions to fine particles.     

Carbonaceous characteristics of atmospheric particulate matter in Hong Kong

To determine the characteristic of carbonaceous species in atmospheric particles in Hong Kong, PM₁₀ and PM_2.5 samples were collected using high volume (hi-vol.) air samplers from November 2000 to February 2001. The organic carbon (OC) and elemental carbon (EC) were analyzed by the selective thermal manganese dioxide oxidation (TMO) method. The ratios of PM_2.5/PM₁₀ mass ratios were 0.61, 0.78 and 0.53 for particulate matter collected at PolyU station (PolyU, near a major traffic corridor), Kwun Tong station (KT, mixed residential/commercial/industrial) and the Hok Tsui background station (HT), respectively. These results indicate that the PM_2.5 concentrations constitute the majority of the PM₁₀ concentrations, especially in urban and industrial areas of Hong Kong. The average concentrations at the three sites ranged from 73.11 to 83.52 μg/m³ for PM₁₀ and from 42.37 to 57.38 μg/m³ for PM_2.5. The highest daily mass concentrations of PM₁₀ and PM_2.5 were 125.89 μg/m³ and 116.89 μg/m³ at KT, respectively. The correlation between PM₁₀ and PM_2.5 was high at KT and HT (r>0.9, P<0.01). This means that the sources of PM₁₀ and PM_2.5 may be the same at both sites. The highest mean concentration of OC (12.02 μg/m³) and EC (6.86 μg/m³) in PM₁₀ was found at the PolyU among the three sites. For PM_2.5, the highest mean concentration of OC (10.16 μg/m³) was at KT while the highest mean concentration of EC (7.95 μg/m³) was at PolyU. However, the background concentrations at HT were higher than another background area, Kosan, Korea. Transportation of pollutants from the Asian continent may be responsible for the elevations of EC+OC at the remote site. More than 74% of the EC and more than 79% of the OC were found in the PM_2.5 fraction at the three sampling locations. At PolyU station, PM_2.5 consisted of 18.18% OC and 11.16% EC while 17.70% OC and 8.81% EC were found in KT station. Thus OC and EC are major constituents of aerosols in Hong Kong. OC/EC ratios for PM₁₀ and PM_2.5 were less than 2 at PolyU and KT stations while the ratio exceeded 3 at HT background station. This indicates that OC measured in the urban area may be emitted directly as a primary aerosol.     

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.     

Monitoring and modeling of household air quality related to use of different Cookfuels in Paraguay

In Paraguay, 49% of the population depends on biomass (wood and charcoal) for cooking. Residential biomass burning is a major source of fine particulate matter (PM_2.5) and carbon monoxide (CO) in and around the household environment. In July 2016, cross‐sectional household air pollution sampling was conducted in 80 households in rural Paraguay. Time‐integrated samples (24 hours) of PM_2.5 and continuous CO concentrations were measured in kitchens that used wood, charcoal, liquefied petroleum gas (LPG), or electricity to cook. Qualitative and quantitative household‐level variables were captured using questionnaires. The average PM_2.5 concentration (μg/m³) was higher in kitchens that burned wood (741.7 ± 546.4) and charcoal (107.0 ± 68.6) than in kitchens where LPG (52.3 ± 18.9) or electricity (52.0 ± 14.8) was used. Likewise, the average CO concentration (ppm) was higher in kitchens that used wood (19.4 ± 12.6) and charcoal (7.6 ± 6.5) than in those that used LPG (0.5 ± 0.6) or electricity (0.4 ± 0.6). Multivariable linear regression was conducted to generate predictive models for indoor PM_2.5 and CO concentrations (predicted R² = 0.837 and 0.822, respectively). This study provides baseline indoor air quality data for Paraguay and presents a multivariate statistical approach that could be used in future research and intervention programs.     

Indoor exposure to particulate matter and the incidence of acute lower respiratory infections among children: A birth cohort study in urban Bangladesh

Approximately half of all children under two years of age in Bangladesh suffer from an acute lower respiratory infection (ALRI) each year. Exposure to indoor biomass smoke has been consistently associated with an increased risk of ALRI in young children. Our aim was to estimate the effect of indoor exposure to particulate matter (PM_2.5) on the incidence of ALRI among children in a low‐income, urban community in Bangladesh. We followed 257 children through two years of age to determine their frequency of ALRI and measured the PM_2.5 concentrations in their sleeping space. Poisson regression was used to estimate the association between ALRI and the number of hours per day that PM_2.5 concentrations exceeded 100 μg/m³, adjusting for known confounders. Each hour that PM_2.5 concentrations exceeded 100 μg/m³ was associated with a 7% increase in incidence of ALRI among children aged 0–11 months (adjusted incidence rate ratio (IRR) 1.07, 95% CI 1.01–1.14), but not in children 12–23 months old (adjusted IRR 1.00, 95% CI 0.92–1.09). Results from this study suggest that reducing indoor PM_2.5 exposure could decrease the frequency of ALRI among infants, the children at highest risk of death from these infections.