Measurements were made during two seasons at five Los Angeles area museums to determine the concentrations of nitric acid in outdoor and indoor air. Mean seasonal indoor nitric acid concentrations ranged from <0.1 to 1.5 µg/m3 corresponding to less than 1% to 40% of the outdoor nitric acid concentration depending on building construction and ventilation system design. A mathematical model was applied to determine whether indoor/outdoor HNO3 concentration ratios can be predicted from data on building parameters and ventilation system design. Good agreement between predicted and measured values was found. The rates of deposition of total inorganic nitrate onto vertical surfaces due to gas-phase plus aerosol-phase pollutants were measured and found to vary from 0.2 to 5.8 ng/m2-sec. Measurements indicate that nearly all of this deposition flux was delivered due to deposition of gas-phase species, but comparison to theoretical HNO3 transport calculations suggests that gaseous species in addition to HNO3 contribute to the observed accumulation of inorganic nitrate.
Article about my work in Caltech On Campus, October, 1990
Another article in Science News of the Week, July 14, 1990: Pigments take thier NOx
Lynn Garry Salmon <>{