title: Respiratory hospital admissions and summertime haze air pollution in Toronto, Ontario: consideration of the role of acid aerosols.
abstract: A study of air pollution and daily hospital admissions for respiratory causes was conducted in Toronto, Ontario. Fine aerosol (da < 2.5 microns) samples were collected daily at a central city site during July and August 1986, 1987, and 1988 and were subsequently extracted and analyzed for daily particulate phase aerosol strong acidity (H+) and sulfates (SO4 =). Daily counts of respiratory admissions to 22 acute care hospitals and daily meteorological and environmental data (e.g. ozone [O3], total suspended particulate matter [TSP], and thoracic particle mass [PM10] were also obtained. Regression analyses indicated that only the O3, H+, and SO4 = associations with respiratory and asthma admissions remained consistently significant after controlling for temperature. Even after excluding days with maximum 1-hr O3 > 120 ppb, O3 was still strongly significant. In the various model specifications considered, the relative particle metric strengths of association with admissions were generally H+ > SO4 = > FP > PM10 > TSP, indicating that particle size and composition are of central importance in defining the adverse human health effects of particulate matter. On average, summertime haze air pollution was associated with 24% of all respiratory admissions (21% with O3, 3% with H+). On peak pollution days, however, aerosol acidity yielded the highest relative risk estimates (e.g., RR = 1.5 at 391 nmole/m3 H+), and summertime haze was associated with roughly half of all respiratory admissions.
authors.affiliation: Nelson Institute of Environmental Medicine, New York University Medical Center, Tuxedo 10987.
authors.forename: G D
authors.initials: GD
authors.lastname: Thurston
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: C G
authors.initials: CG
authors.lastname: Hayes
authors.forename: D V
authors.initials: DV
authors.lastname: Bates
authors.forename: M
authors.initials: M
authors.lastname: Lippmann
mesh_terms: D000143:Acids / Q000009:adverse effects* / Q000032:analysis; D000336:Aerosols; D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009864:Ontario / Q000453:epidemiology; D010126:Ozone / Q000009:adverse effects / Q000032:analysis; D012044:Regression Analysis; D012140:Respiratory Tract Diseases / Q000453:epidemiology / Q000209:etiology*; D012621:Seasons; D013431:Sulfates / Q000009:adverse effects / Q000032:analysis; D013696:Temperature
chemical_list: D000143:Acids; D000336:Aerosols; D013431:Sulfates; D010126:Ozone