Effects of aqueous extracts of PM10 filters from the Utah Valley on human airway epithelial cells

We hypothesized that the reduction in hospital respiratory admissions in th e Utah Valley during closure of a local steel mill in 1986-1987 was attribu table in part to decreased toxicity of ambient air particles. Sampling filt ers for particulate matter < 10 mu m (PM10) were obtained from a Utah Valle y monitoring station for the year before (year 1), during (year 2), and aft er (year 3) the steel mill closure. Aqueous extracts of the filters were an alyzed for metal content and oxidant production and added to cultures of hu man respiratory epithelial (BEAS-2B) cells for 2 or 24 h. Year 2 dust conta ined the lowest concentrations of soluble iron, copper, and zinc and showed the least oxidant generation. Only dust from year 3 caused cytotoxicity (b y microscopy and lactate dehydrogenase release) at 500 mu g/ml. Year 1 and year 3, but not year 2, dust induced expression of interleukin-6 and -8 in a dose-response fashion. The effects of ambient air particles on human resp iratory epithelial cells vary significantly with time and metal concentrati ons.