AN ENVIRONMENTAL SCOPING STUDY IN THE LOWER RIO-GRANDE VALLEY OF TEXAS .3. RESIDENTIAL MICROENVIRONMENTAL MONITORING FOR AIR, HOUSE-DUST, AND SOIL

A principal aspect of the 1993 Lower Rio Grande Valley Environmental S coping Study was the analysis and interpretation of residential air, h ousehold dust, and soil pollutant concentration data for exposure asse ssments. Measurements included respirable particulate matter (PM2.5), volatile organic compounds (VOCs), pesticides, and polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor air. Household dust, road d ust, and yard soil were analyzed for elements, pesticides, and PAHs. N ine residences were monitored for three weeks in the spring of 1993. A dditional monitoring was conducted at six of the nine residences for t en days the following summer. Generally good agreement was found betwe en outdoor residential air and same-species measurements collected con currently at a non-residential central site in Brownsville, TX (Ellens on et al. 1997) for fine particulate matter, elements, and VOCs indica ting the dominance of regional influences. PM2.5 mass and element conc entrations in residential indoor and outdoor air were generally higher in the summer than in the spring. Indoor air concentrations of many s pecies were higher than outdoor air concentrations and were attributed to household activities, ventilation of residences, and track-in of d islodged soils. Evidence of agricultural activities was noted in the o ccurrence of crop-related pesticides (e.g., malathion and chlorpyrifos ) in indoor and outdoor air. Concentrations of common household pestic ides (e.g., chlordane, chlorpyrifos, diazinon, heptachlor, and propoxu r) were generally higher indoors than outdoors and were also present i n house dust. Seasonal comparisons of pesticides and PAHs were also pr esented using matched residences in spring and summer; VOCs also may h ave indicated seasonal effects. VOCs (notably propane and butane isome rs) and PAHs were higher indoors, presumably due to cooking-related ac tivities. Published by Elsevier Science Ltd.