The 1998 Baltimore Particulate Matter Epidemiology–Exposure Study: Part 1. Comparison of ambient, residential outdoor, indoor and apartment particulate matter monitoring

Abstract

A combined epidemiological–exposure panel study was conducted during the summer of 1998 in Baltimore, Maryland. The objectives of the exposure analysis component of the 28-day study were to investigate the statistical relationships between particulate matter (PM) and related co-pollutants from numerous spatial boundaries associated with an elderly population, provide daily mass concentrations needed for the epidemiological assessment, and perform an extensive personal exposure assessment. Repeated 24-h integrated PM_2.5 (n=394) and PM₁₀ (n=170) data collections corresponding to stationary residential central indoor, individual apartment, residential outdoor and ambient monitoring were obtained using the same sampling methodology. An additional 325 PM_2.5 personal air samples were collected from a pool of 21 elderly (65+ years of age) subjects. These subjects were residents of the 18-story retirement facility where residential monitoring was conducted. Mean daily central indoor and residential apartment concentrations were approximately 10 µg/m³. Outdoor and ambient PM_2.5 concentrations averaged 22 µg/m³ with a daily range of 6.7–59.3 µg/m³. The slope of the central indoor/outdoor PM_2.5 mass relationship was 0.38. The average daily ratio of PM_2.5/PM₁₀ mass co ncentrations across the measurement sites ranged from 0.73 to 0.92. Both the central indoor and mean apartment PM_2.5 mass concentrations were highly correlated with the outdoor variables (r>0.94). The lack of traditionally recognized indoor sources of PM present within the facility might have accounted for the high degree of correlation observed between the variables. Results associated with the personal monitoring effort are discussed in depth in Part 2 of this article.