GULF COAST STUDY OF URBAN AIR POLLUTION AND RESPIRATORY FUNCTION (SURF)

Abstract

ISEE-78 Introduction: The purpose of this study was to identify and evaluate exposure to and effects of urban air pollutants on respiratory function in an occupational cohort of beach lifeguards. This area of the Gulf Coast is adjacent to many point sources of air toxics, including major petrochemical industrial complexes and heavily trafficked roads and highways. It is also a consistent non-attainment area for compliance with number of days during which ozone concentrations exceed permissible levels. The need to determine health effects associated with air pollution has thus increased. Methods: The lifeguard occupational cohort includes >100 guards, ages 16-27, working 10-hour shifts and sustaining continuous ambient air exposures. A “natural” experiment was facilitated, given that guards are traditionally exposed to low levels of photochemically formed air pollutants during summer mornings and high levels (reaching seasonal peaks) in the afternoons. Three times daily, each lifeguard performed computerized spirometry, according to ATS standards, to measure air flow rates and lung volumes: in the morning prior to exercise (baseline), following a one-hour strenuous cardiovascular workout, and again in the afternoon following sustained exposure to ambient air. Each guard also completed an initial survey, detailing family and personal history of asthma, smoke exposure, and lung disease as well as daily surveys documenting potential confounders including recent illness, medication use, and smoke exposure. Hourly measurements of ozone, oxides of nitrogen, nitrogen dioxide, sulfur dioxide, and particulates (PM2.5) were obtained from a regulated monitoring site at the local airport. Meteorologic data collected include wind speed, wind direction, temperature, and relative humidity. Results: Univariate statistics revealed normally distributed data meeting assumptions of homogeneity of variance for ANOVA, which showed a significant difference (p<0.05) between morning and afternoon lung function measures. Linear regression revealed a significant decrease in FVC and FEV1 after exposure to increasing levels of PM2.5 for several hours. Discussion: Results indicate a decrease in total lung volume (preserved FEV1/FVC ratio) rather than typical patterns of airway obstruction due to bronchospasm as seen in asthma exacerbations (FEV1 reduced more than FVC)—even at relatively low levels of PM2.5. While federal air quality standards list PM2.5 levels >65 μg/m3 as unhealthy, we have seen average lung volumes decrease by as much as 0.5 liters (5-30%) with maximum PM2.5 concentrations of only 38 μg/m3. This may have implications for environmental recommendations and regulations as well as disease prevention, in that our data suggest that even tighter standards may be necessary.