Faculty Bibliography

BACKGROUND:Commercial databases can be used to identify participant addresses over time, but their quality and impact on environmental exposure assessment is uncertain. OBJECTIVE:To evaluate the performance of a commercial database to find residences and estimate environmental exposures for study participants. METHODS:We searched LexisNexis® for participant addresses in the Los Angeles Ultrafines Study, a prospective cohort of men and women aged 50-71 years. At enrollment (1995-1996) and follow-up (2004-2005), we evaluated attainment (address found for the corresponding time period) and match rates to survey addresses by participant characteristics. We compared geographically-referenced predictors and estimates of ultrafine particulate matter (UFP) exposure from a land use regression model using LexisNexis and survey addresses at enrollment. RESULTS:LexisNexis identified an address for 69% of participants at enrollment (N=50,320) and 95% of participants at follow-up (N=24,432). Attainment rate at enrollment modestly differed (≥5%) by age, smoking status, education, and residential mobility between surveys. The match rate at both survey periods was high (82-86%) and similar across characteristics. When using LexisNexis versus survey addresses, correlations were high for continuous values of UFP exposure and its predictors (rho=0.86-0.92). SIGNIFICANCE/CONCLUSIONS:Time period and population characteristics influenced the attainment of addresses from a commercial database, but accuracy and subsequent estimation of specific air pollution exposures were high in our older study population.

OBJECTIVES/OBJECTIVE:The goals of this study were to assess the air quality in subway systems in the northeastern United States and estimate the health risks for transit workers and commuters. METHODS: RESULTS: DISCUSSION/CONCLUSIONS:

Food carts are common along streets in cities throughout the world. In North America, food cart vendors generally use propane, charcoal, or both propane and charcoal (P and C) for food preparation. Although cooking emissions are known to be a major source of indoor air pollution, there is limited knowledge on outdoor cooking's impact on the ambient environment and, in particular, the relative contribution of the different cooking fuels. This field study investigated the air pollution the public is exposed to in the micro-environment around 19 food carts classified into 3 groups: propane, charcoal, and P and C carts. Concentrations near the food carts were measured using both real-time and filter-based methods. Mean real-time concentrations of PM_2.5, BC_2.5, and particle counts were highest near the charcoal food carts: 196 μg/m³, 5.49 μg/m³, and 69,000 particles/cm³, respectively, with peak exposures of 1520 μg/m³, 67.9 μg/m³, and 235,000 particles/cm³, respectively. In order of pollution emission impacts: charcoal > P and C > propane carts. Thus, significant differences in air pollution emissions occurred in the vicinity of mobile food carts, depending on the fuel used in food preparation. Local air pollution polices should consider these emission factors in regulating food cart vendor operations.

In Dhaka, Bangladesh, fine particulate matter (PM_2.5) air pollution shows strong seasonal trends, with significantly higher mean concentrations during winter than during the monsoon (winter = 178.1 μg/m³ vs. monsoon = 30.2 μg/m³). Large-scale open burning of post-harvest agricultural waste across the Indo-Gangetic Plain is a major source of PM_2.5 air pollution in northern India during the non-monsoon period. This study evaluates the extent to which the seasonal differences in PM_2.5 pollution concentrations in Dhaka are accounted for by biomass-burning vs. fossil-fuel combustion sources. To assess this, an index was developed based on elemental potassium (K) as a marker for biomass particulate matter, after adjusting for soil-associated K contributions. Alternatively, particulate sulfur was employed as a tracer index for fossil-fuel combustion PM_2.5. By simultaneously regressing total PM_2.5 on S and adjusted K, the PM_2.5 mass for each day was apportioned into: 1) fossil-fuels combustion associated PM_2.5; 2) biomass-burning associated PM_2.5; and, 3) all other PM_2.5. The results indicated that fossil-fuel combustion contributed 21.6% (19.5 μg/m³), while biomass contributed 40.2% (36.3 μg/m³) of overall average PM_2.5 from September 2013 to December 2017. However, the mean source contributions varied by season: PM_2.5 in Dhaka during the monsoon season was dominated by fossil-fuels sources (44.3%), whereas PM_2.5 mass was dominated by biomass-burning (41.4%) during the remainder of the year. The contribution to PM_2.5 and each of its source components by transport of pollution into Dhaka during non-monsoon time was also evaluated by: 1) Conditional bivariate (CBPF) and pollution rose plots; 2) Concentration weighted trajectories (CWT), and; 3) NASA satellite photos to identify aerosol loading and fire locations on high pollution days. The collective evidence indicates that, while the air pollution in Dhaka is contributed to by both local and transboundary sources, the highest pollution days were dominated by biomass-related PM_2.5, during periods of crop-burning in the Indo-Gangetic Plain.

Outdoor air pollution is a major contributor to the burden of disease worldwide. Most of the global population resides in places where air pollution levels, because of emissions from industry, power generation, transportation, and domestic burning, considerably exceed the World Health Organization's health-based air-quality guidelines. Outdoor air pollution poses an urgent worldwide public health challenge because it is ubiquitous and has numerous serious adverse human health effects, including cancer. Currently, there is substantial evidence from studies of humans and experimental animals as well as mechanistic evidence to support a causal link between outdoor (ambient) air pollution, and especially particulate matter (PM) in outdoor air, with lung cancer incidence and mortality. It is estimated that hundreds of thousands of lung cancer deaths annually worldwide are attributable to PM air pollution. Epidemiological evidence on outdoor air pollution and the risk of other types of cancer, such as bladder cancer or breast cancer, is more limited. Outdoor air pollution may also be associated with poorer cancer survival, although further research is needed. This report presents an overview of outdoor air pollutants, sources, and global levels, as well as a description of epidemiological evidence linking outdoor air pollution with cancer incidence and mortality. Biological mechanisms of air pollution-derived carcinogenesis are also described. This report concludes by summarizing public health/policy recommendations, including multilevel interventions aimed at individual, community, and regional scales. Specific roles for medical and health care communities with regard to prevention and advocacy and recommendations for further research are also described.

Air pollution is a major contributor to cardiovascular morbidity and mortality. Fine particulate matter <2.5 µm in diameter may be a modifiable risk factor for hypertension. The benefits of in-home air filtration on systolic blood pressure (BP) and diastolic BP are unclear. To examine the effects of in-home personal air cleaner use on fine particulate exposure and BP, we queried PubMed, Web of Science, Cochrane Central Register, Inspec, and EBSCO GreenFILE databases for relevant clinical trials. Included studies were limited to nonsmoking participants in smoke-free homes with active or sham filtration on indoor fine particulate concentrations and changes in systolic and diastolic BP. Of 330 articles identified, 10 trials enrolling 604 participants who met inclusion criteria were considered. Over a median 13.5 days, there was a significant reduction of mean systolic BP by ≈4 mm Hg (-3.94 mm Hg [95% CI, -7.00 to -0.89]; P=0.01) but a nonsignificant difference in mean diastolic BP (-0.95 mm Hg [95% CI, -2.81 to 0.91]; P=0.32). Subgroup analyses indicated no heterogeneity of effect by age, level of particulate exposure, or study duration. Given the variation in study design, additional study is warranted to confirm and better quantify the observed benefits in systolic BP found with personal air cleaner use.

Although it is well accepted that air pollution exposure exacerbates preexisting airway disease, it has not been firmly established that long-term pollution exposure increases the risk of new-onset asthma or chronic obstruction pulmonary disease (COPD). This Workshop brought together experts on mechanistic, epidemiological, and clinical aspects of airway disease to review current knowledge regarding whether air pollution is a causal factor in the development of asthma and/or COPD. Speakers presented recent evidence in their respective areas of expertise related to air pollution and new airway disease incidence, followed by interactive discussions. A writing committee summarized their collective findings. The Epidemiology Group found that long-term exposure to air pollution, especially metrics of traffic-related air pollution such as nitrogen dioxide and black carbon, is associated with onset of childhood asthma. However, the evidence for a causal role in adult-onset asthma or COPD remains insufficient. The Mechanistic Group concluded that air pollution exposure can cause airway remodeling, which can lead to asthma or COPD, as well as asthma-like phenotypes that worsen with long-term exposure to air pollution, especially fine particulate matter and ozone. The Clinical Group concluded that air pollution is a plausible contributor to the onset of both asthma and COPD. Available evidence indicates that long-term exposure to air pollution is a cause of childhood asthma, but the evidence for a similar determination for adult asthma or COPD remains insufficient. Further research is needed to elucidate the exact biological mechanism underlying incident childhood asthma, and the specific air pollutant that causes it.