Air pollution and multiple acute respiratory outcomes

Abstract

Short-term effects of air pollutants on respiratory mortality and morbidity have been consistently reported but usually studied separately. To more completely assess air pollution effects, we studied hospitalisations for respiratory diseases together with out-of-hospital respiratory deaths. A time-stratified case-crossover study was carried out in six Italian cities from 2001 to 2005. Daily particulate matter (particles with a 50% cut-off aerodynamic diameter of 10 μm (PM10)) and nitrogen dioxide (NO2) associations with hospitalisations for respiratory diseases (n5100 690), chronic obstructive pulmonary disease (COPD) (n538 577), lower respiratory tract infections (LRTI) among COPD patients (n59886) and out-of-hospital respiratory deaths (n55490) were estimated for residents aged o35 years. For an increase of 10 μgm-3 in PM10, we found an immediate 0.59% (lag 01 days) increase in hospitalisations for respiratory diseases and a 0.67% increase for COPD; the 1.91% increase in LRTI hospitalisations lasted longer (lag 03 days) and the 3.95% increase in respiratory mortality lasted 6 days. Effects of NO2 were stronger and lasted longer (lag 05 days). Age, sex and previous ischaemic heart disease acted as effect modifiers for different outcomes. Analysing multiple rather than single respiratory events shows stronger air pollution effects. The temporal relationship between the pollutant increases and hospitalisations or mortality for respiratory diseases differs. Copyright © ERS 2013.