The air quality health index and emergency department visits for injury

Abstract

Abstract Introduction. The purpose of this study was to investigate the associations of ambient air quality with emergency department (ED) visits for injury. Aim. To explore correlations between ED visits for injury and ambient air pollution. Materials and methods. Considered health outcomes are ED visits for injury (ICD-9 codes: 800-999) in Edmonton, Canada, for the period from April 1998 to March 2002 (1,444 days). Air pollution concentration in the ambient air is represented as a daily maximum of the Air Quality Health Index (AQHI). The AQHI value encapsulates levels of three urban ambient air pollutants (ozone, nitrogen dioxide and fine particulate matter), weighted by constant risk coefficients. A time-stratified casecrossover design, using conditional logistic regression and conditional Poisson regression, was realized to assess the associations. The risk, reported as odds ratio and relative risk, was estimated using log-linear models and parametric non-linear concentrationresponse functions. Results. The strongest effects were observed for young male patients in the cold season (October-March). Lagged exposures were found to have positive statistically significant associations. Discussion. The study results indicate that air quality was associated with increased risk of daily ED visits for injury. This study determined concentration-response functions which allow one to assess the effects for various levels of the AQHI.