Generation Of Hydroxyl Radicals From Ambient Fine Particles In A Surrogate Lung Fluid Solution

摘要

While it has been hypothesized that the adverse health effects associated with ambient paniculate matter (PM) are due to production of hydroxyl radical (OH), few studies have quantified OH production from PM. Here we report the amounts of OH produced from ambient fine particles (PM_2.5) collected in northern California and extracted in a cell-free surrogate lung fluid (SLF). On average, the extracted particles produced 470 nmol·OH mg~(-1)-PM(2.5) during our 15-month collection period. There was a clear seasonal pattern in the efficiency with which particles generated OH, with highest production during spring and summer and lowest during winter. In addition, nighttime PM was typically more efficient than daytime PM at generating OH. Transition metals played the dominant role in OH production: on average (±σ), the addition of desfer-oxamine (a chelator that prevents metals from forming OH) to the SLF removed (90 ± 5) % of OH generation. Furthermore, based on the concentrations of Fe in the PM_(2.5) SLF extracts, and the measured yield of OH as a function of Fe concentration, dissolved iron can account for the majority of OH produced in most of our PM_(2.5) extracts.