title: Who is sensitive to the effects of particulate air pollution on mortality? A case-crossover analysis of effect modifiers.
abstract: BACKGROUND
  Populations susceptible to the effects of particulate matter have begun to be characterized, but the independent contributions of specific factors have not been explored.
  
  
  METHODS
  We used a case-crossover study to examine PM10-associated mortality risk during 1988-1991 among 65,180 elderly residents of Cook County, Illinois, who had a history of hospitalization for heart or lung disease. We assessed how the effect was independently modified by specific diagnoses and personal characteristics.
  
  
  RESULTS
  We found a 1.14% (95% confidence interval [CI] = 0.44% to 1.85%) increased risk of death per 10 microg/m3 increase in ambient PM10 concentration. Persons with heart or lung disease-but no specific diagnosis of myocardial infarction, diabetes, congestive heart failure, chronic obstructive pulmonary disorder, or conduction disorders-were at 0.74% (-0.29% to 1.79%) increased risk. Persons with a history of myocardial infarction had a 2.7-fold higher risk (CI = -2.1 to 7.4). Those with diabetes carried a 2.0-fold higher risk (CI = -1.5 to 5.5). Risk appeared to decrease with age among elderly men and increase with age among elderly women, but the estimated 3-way interaction was not precise enough to exclude the null. We found no indication that susceptibility varied by group-level socioeconomic measures.
  
  
  CONCLUSIONS
  Among a frail population, individuals diagnosed with myocardial infarction or diabetes were at greatest risk of death associated with high concentrations of PM10. These results suggest that their susceptibility may derive from prior vascular damage to the heart.
authors.affiliation: Environmental Epidemiology Program, Harvard School of Public Health, Boston, Massachusetts, USA. tbateson@post.harvard.edu
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Bateson
authors.forename: Joel
authors.initials: J
authors.lastname: Schwartz
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects*; D002318:Cardiovascular Diseases / Q000145:classification / Q000453:epidemiology / Q000401:mortality*; D002641:Chicago / Q000453:epidemiology; D016001:Confidence Intervals; D004522:Educational Status; D005260:Female; D006760:Hospitalization; D006801:Humans; D007182:Income; D008171:Lung Diseases / Q000145:classification / Q000453:epidemiology / Q000401:mortality*; D008297:Male
chemical_list: D000393:Air Pollutants