title: Exposures to acidic aerosols.
abstract: Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m3 more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H+ determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr H+ concentrations exceeded 550 nmole/m3 (approximately 27 micrograms/m3 H2SO4). The maximum estimated 1-hr concentration exceeded 1500 nmole/m3 for H+ ions. At these concentrations, an active child might receive more than 2000 nmole of H+ ion in 12 hr and in excess of 900 nmole during the hour when H2SO4 exceeded 50 micrograms/m3.
authors.affiliation: School of Public Health, Harvard University, Boston, MA 02115.
authors.forename: J D
authors.initials: JD
authors.lastname: Spengler
authors.forename: G J
authors.initials: GJ
authors.lastname: Keeler
authors.forename: P
authors.initials: P
authors.lastname: Koutrakis
authors.forename: P B
authors.initials: PB
authors.lastname: Ryan
authors.forename: M
authors.initials: M
authors.lastname: Raizenne
authors.forename: C A
authors.initials: CA
authors.lastname: Franklin
mesh_terms: D015258:Acid Rain / Q000032:analysis*; D000336:Aerosols; D000393:Air Pollutants / Q000032:analysis*; D006801:Humans; D008452:Maximum Allowable Concentration; D009589:Nitrogen Oxides / Q000032:analysis; D012137:Respiratory System / Q000187:drug effects; D012307:Risk Factors; D012621:Seasons; D013458:Sulfur Dioxide / Q000032:analysis; D013464:Sulfuric Acids / Q000032:analysis
chemical_list: D015258:Acid Rain; D000336:Aerosols; D000393:Air Pollutants; D009589:Nitrogen Oxides; D013464:Sulfuric Acids; D013458:Sulfur Dioxide; C033158:sulfuric acid