The transformation of outdoor ammonium nitrate aerosols in the indoor environment

• Published in: Atmospheric environment (1994) Vol. 37; no. 39; pp. 5633 - 5644
• Main Authors: Lunden, Melissa M., Revzan, Kenneth L., Fischer, Marc L., Thatcher, Tracy L., Littlejohn, David, Hering, Susanne V., Brown, Nancy J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01-12-2003; Elsevier Science
• Subjects: Aerosols; Ammonia; ammonium nitrate; Applied sciences; Atmospheric pollution; Biological and medical sciences; Buildings. Public works; Chemical transformation; Environment. Living conditions; Exact sciences and technology; Housing. Living conditions; Indoor particulate nitrate; Medical sciences; Nitric acid; Penetration; Pollution; Pollution indoor buildings; Pollution sources. Measurement results; Public health. Hygiene; Public health. Hygiene-occupational medicine; California; United States; North America; America; USA, California; Aerosols; Ammonia; Chemical transformation; Penetration; Indoor particulate nitrate; Nitric acid; Pollutant behavior; Reaction product; Air quality; Exposure; Housing; Sulfates; Health and environment; Chemical reaction; Fine particle; Ammonium nitrate; Indoor pollution; Indoor outdoor ratio; Material balance; Public health
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2003.09.035

Recent studies associate particulate air pollution with adverse health effects; however, the exposure to indoor particles of outdoor origin is not well characterized, particularly for individual chemical species. We conducted a field study in an unoccupied, single-story residence in Clovis, California to provide data and analyses to address issues important for assessing exposure. We used real-time particle monitors both outdoors and indoors to quantify nitrate, sulfate, and carbon particulate matter of particle size 2.5
μm or less in diameter (PM-2.5). The results show that measured indoor ammonium nitrate concentrations were significantly lower than would be expected based solely on penetration and deposition losses. The additional reduction can be attributed to the transformation indoors of ammonium nitrate into ammonia and nitric acid gases, which are subsequently lost by deposition and sorption to indoor surfaces. A mass balance model that accounts for the kinetics of ammonium nitrate evaporation was able to reproduce measured indoor ammonium nitrate and nitric acid concentrations, resulting in a fitted value of the deposition velocity for nitric acid of 0.56
cm
s
−1. The results indicate that indoor exposure to outdoor ammonium nitrate in Central Valley of California are small, and suggest that exposure assessments based on total particle mass measured outdoors may obscure the actual causal relationships for indoor exposure to particles of outdoor origin.