Michael G. Apte

Air pollution and the energy ladder in asian cities

Household fuel switching from lower to higher quality fuels, i.e. movement up the “energy ladder,” generally leads to substantially lower emissions of health-damaging pollutants. The extent to which human exposures are reduced is difficult to predict, however, because of interactions due to penetration of outdoor pollutants into homes and vice versa. In order to help answer the question of how much exposures might be reduced by movement up the energy ladder, a three-city household air pollution study covering particulates (PM10), nitrogen dioxide (NO2), and carbon monoxide (CO) was conducted in and near households spanning the most important current steps in each citys energy ladder. Steps examined were biomass-kerosene-gas in Pune, India; coal-gas in Beijing, China; and charcoal-gas in Bangkok, Thailand. In most instances, 24-hour sampling was conducted and some personal monitoring was undertaken during cooking periods. Preliminary calculations of the exposure and health implications of fuel switching are presented.

Determining size-specific emission factors for environmental tobacco smoke particles

Because size is a major controlling factor for indoor airborne particle behavior, human particle exposure assessments will benefit from improved knowledge of size-specific particle emissions. We report a method of inferring size-specific mass emission factors for indoor sources that makes use of an indoor aerosol dynamics model, measured particle concentration time series data, and an optimization routine. This approach provides--in addition to estimates of the emissions size distribution and integrated emission factors--estimates of deposition rate, an enhanced understanding of particle dynamics, and information about model performance. We applied the method to size-specific environmental tobacco smoke (ETS) particle concentrations measured every minute with an 8-channel optical particle counter (PMS-LASAIR; 0.1 m 2+ w m diameters) and every 10 or 30 min with a 34-channel differential mobility particle sizer (TSI-DMPS; 0.01 m 1+ w m diameters) after a single cigarette or cigar was machine-smoked inside a low air-exchange-rate 20 m 3 chamber. The aerosol dynamics model provided good fits to observed concentrations when using optimized values of mass emission rate and deposition rate for each particle size range as input. Small discrepancies observed in the first 1-2 h after smoking are likely due to the effect of particle evaporation, a process neglected by the model. Size-specific ETS particle emission factors were fit with log-normal distributions, yielding an average mass median diameter of 0.2 w m and an average geometric standard deviation of 2.3 with no systematic differences between cigars and cigarettes. The equivalent total particle emission rate, obtained by integrating each size distribution, was 0.2-0.7 mg/min for cigars and 0.7-0.9 mg/min for cigarettes.

An Exploratory Analysis of the Relationship Between Mortality and the Chemical Composition of Airborne Particulate Matter.

We explored relationships between daily mortality and the major sources of airborne particulate matter (PM) using a newly developed approach, Factor Analysis and Poisson Regression (FA/PR). We hypothesized that by adding information on PM chemical speciation and source apportionment to typical PM epidemiological analysis, we could identify PM sources that cause adverse health effects. The FA/PR method was applied to a merged data set of mortality and extensive PM chemical speciation (including trace metals, sulfate, and extractable organic matter) in New Jersey. Statistically significant associations were found between mortality and several of the FA-derived PM sources, including oil burning, industry, sulfate aerosol, and motor vehicles. The FA/PR method provides new insight into potentially important PM sources related to mortality. For the data set we analyzed, the use of FA/PR to integrate multiple chemical species into source-related PM exposure metrics was found to be a more sensitive tool than the traditional approach using PM mass alone.

Association of Classroom Ventilation with Reduced Illness Absence: A Prospective Study in California Elementary Schools

Abstract Limited evidence associates inadequate classroom ventilation rates (VRs) with increased illness absence (IA). We investigated relationships between VRs and IA in California elementary schools over two school years in 162 3rd–5th‐grade classrooms in 28 schools in three school districts: South Coast (SC), Bay Area (BA), and Central Valley (CV). We estimated relationships between daily IA and VR (estimated from two year daily real‐time carbon dioxide in each classroom) in zero‐inflated negative binomial models. We also compared IA benefits and energy costs of increased VRs. All school districts had median VRs below the 7.1 l/s‐person California standard. For each additional 1 l/s‐person of VR, IA was reduced significantly (p<0.05) in models for combined districts (−1.6%) and for SC (−1.2%), and nonsignificantly for districts providing less data: BA (−1.5%) and CV (−1.0%). Assuming associations were causal and generalizable, increasing classroom VRs from the California average (4 l/s‐person) to the State standard would decrease IA by 3.4%, increase attendance‐linked funding to schools by

Volatile organic compounds in small- and medium-sized commercial buildings in California

33 million annually, and increase costs by only

Outdoor ozone and building‐related symptoms in the BASE study

4 million. Further increasing VRs would provide additional benefits. These findings, while requiring confirmation, suggest that increasing classroom VRs above the State standard would substantially decrease illness absence and produce economic benefits.

Indoor air pollution due to emissions from wood-burning stoves

While small- and medium-sized commercial buildings (SMCBs) make up 96% of the commercial buildings in the U.S., serving a large variety of uses, little information is available on indoor air quality (IAQ) in SMCBs. This study investigated 37 SMCBs distributed across different sizes, ages, uses, and regions of California. We report indoor concentrations and whole building emission rates of a suite of 30 VOCs and aldehydes in these buildings. There was a considerable range in the concentrations for each of the contaminants, especially for formaldehyde, acetaldehyde, decamethylcyclopentasiloxane, d-limonene, 2-butoxyethanol, toluene, 2,2,4-trimethylpentanediol diisobutyrate, and diethylphthalate. The cause of higher concentrations in some building categories generally corresponded to expected sources, for example, chloroform was higher in restaurants and grocery stores, and formaldehyde was higher in retail stores and offices. Factor analysis suggests sources in SMCBs include automobile/traffic, cleaning products, occupant sources, wood products/coating, and plasticizers. The comparison to health guidelines showed that formaldehyde concentrations were above the chronic RELs required by the OEHHA (9 μg/m³) in 86% of the buildings. Data collected in this study begins to fill the knowledge gap for IAQ in SMCBs and helps us understand the indoor sources of VOCs to further improve indoor air quality in SMCBs.

Effect of Temperature and Humidity on Formaldehyde Emissions in Temporary Housing Units

UNLABELLED Reactions between ozone and indoor contaminants may influence human health and indoor air quality. The U.S. EPA Building Assessment Survey and Evaluation (BASE) study data were analyzed for associations between ambient ozone concentrations and building-related symptom (BRS) prevalence. Multiple logistic regression (MLR) models, adjusted for personal, workplace, and environmental variables, revealed positive relationships (P < 0.05) between ambient ozone concentrations and upper respiratory (UR), dry eyes, neurological and headache BRS (odds ratios ranged from 1.03 to 1.04 per 10 mug/m(3) increase in ambient ozone concentrations). Other BRS had marginally significant relationships with ambient ozone (P < 0.10). A linear dose-response in UR symptoms was observed with increasing ambient ozone (P = 0.03); most other symptoms showed similar but not statistically significant trends. Ambient ozone correlated with indoor concentrations of some aldehydes, a pattern suggesting the occurrence of indoor ozone chemistry. Coupled with the MLR ambient ozone-BRS analysis, this correlation is consistent with the hypothesis that ozone-initiated indoor reactions play an important role in indoor air quality and building occupant health. Replication with increased statistical power and with longitudinal data is needed. If the observed associations are confirmed as causal, ventilation system ozone removal technologies could reduce UR BRS prevalence when higher ambient ozone levels are present. PRACTICAL IMPLICATIONS This paper provides strong statistical evidence that supports (but does not prove) the hypothesis that ozone entrained into buildings from the outdoor air is involved in increasing the frequency that occupants experience and a range of upper and lower respiratory, mucosal and neurological symptoms by as much as a factor of 2 when ambient ozone levels increase from those found in low-ozone regions to those typical of high-ozone regions. Although replication is needed, the implication is that reducing the amount of ozone entrained into building ventilation systems, either by ambient pollution reduction or engineered gas-phase filtration, may substantially reduce the prevalence of these symptoms experienced by occupants.

Air filter materials, outdoor ozone and building-related symptoms in the BASE study.

Four wood-burning stoves, three airtight and one non-airtight, were operated in a single-floor 236-m/sup 3/ residence and tested for indoor pollutant emissions. Results showed the airtight stoves emitted minor amounts of carbon monoxide and respirable suspended particles during door-opening operations, while the nonairtight stove continuously injected pollutants indoors under certain operating conditions. During airtight stove operation, carbon monoxide levels reached a maximum of 4 ppm, while average total suspended particulate levels ranged from 24 to 71 ..mu..g/m/sup 3/. During normal nonairtight stove operation, carbon monoxide levels reached a maximum of 8 ppm, while total suspended particulate levels ranged from 30 to 650/sup +/g/m/sup 3/. Outdoor carbon monoxide levels were 1.1 ppm or less, and outdoor particulate levels ranged from 7 to 31 ..mu..g/m/sup 3/. Five polycyclic aromatic hydrocarbons, including benzo(a)pyrene, were measured in the collected particulate samples, and the results are reported. Source strengths for carbon monoxide, total suspended particles, and five polycyclic aromatic hydrocarbons are reported. 26 references, 4 figures, 5 tables.

Indoor Air Pollution Due to Emissions from Unvented Gas-Fired Space Heaters

ABSTRACT The effect of temperature and humidity on formaldehyde emissions from samples collected from temporary housing units (THUs) was studied. The THUs were supplied by the U.S. Federal Emergency Management Administration (FEMA) to families that lost their homes in Louisiana and Mississippi during the Hurricane Katrina and Rita disasters. On the basis of a previous study, four of the composite wood surface materials that dominated contributions to indoor formaldehyde were selected to analyze the effects of temperature and humidity on the emission factors. Humidity equilibration experiments were carried out on two of the samples to determine how long the samples take to equilibrate with the surrounding environmental conditions. Small chamber experiments were then conducted to measure emission factors for the four surface materials at various temperature and humidity conditions. The samples were analyzed for formaldehyde via high-performance liquid chromatography. The experiments showed that increases in temperature or humidity contributed to an increase in emission factors. A linear regression model was built using the natural log of the percent relative humidity (RH) and inverse of temperature (in K) as independent variables and the natural log of emission factors as the dependent variable. The coefficients for the inverse of temperature and log RH with log emission factor were found to be statistically significant for all of the samples at the 95% confidence level. This study should assist in retrospectively estimating indoor formaldehyde exposure of occupants of THUs. IMPLICATIONS Maddalena et al. reported differences between formalde-hyde concentrations in samples collected from the THUs during the morning and afternoon of the same day, highlighting the need to carry out further analysis on the effect of temperature and humidity on formaldehyde emissions. This study addresses the influence of temperature and humidity on formaldehyde emission factors from individual materials. The information provided can be incorporated into an exposure assessment study for the occupants of the FEMA trailers. However, because the experiments are carried out only on four samples from the THUs, they might not be representative of the entire fleet of THUs.