Ambient particle source apportionment and daily hospital admissions among children and elderly in Copenhagen

An association between particulate air pollution and morbidity and mortality is well established. However, little is known about which sources of particulate matter contribute most to the adverse health effects. Identification of responsible sources would merit more efficient control. For a 6-year period (01 January 1999 to 31 December 2004), we examined associations between urban background PM₁₀ in the presence of gaseous pollutants (CO, NO ₂) and hospital admissions due to cardiovascular and respiratory disease in the elderly (age≥65), and asthma in children (age 5-18) in Copenhagen, Denmark. We further studied associations between fractions of PM₁₀ assigned to six sources (biomass, secondary, oil, crustal, sea salt, and vehicle) and admissions during a 11/2-year campaign. We used Poisson generalized additive time-series model adjusted for season, day of the week, public holidays, influenza epidemics, grass pollen, school holidays, and meteorology, with up to 5 days lagged air pollution exposure. We found positive associations between PM₁₀ and the three health outcomes, with strongest associations for asthma. The PM₁₀ effect remained robust in the presence of CO and NO₂. We found different PM₁₀ sources to be variably associated with different outcomes: crustal and secondary sources showed strongest associations with cardiovascular, biomass with respiratory, and vehicle with asthma admissions. These novel results may merit future research of potential mechanism, whereas at present, no single PM ₁₀ source can be attributed to all morbidity.