Castner J, et al. - This study was performed to identify air pollutants that increased the risk of asthma emergency department visits amid a time wherein a polluting factory was criminally convicted, changing local air pollutant levels. It was concluded that the pollutants NO2, PM2.5 CO, and O3 were related to increased emergency asthma visits in some, but not all months of the year. Air pollution's effect on asthma emergencies may be masked by other, more influential seasonal triggers, such as infections or allergies.

Methods

• For this study, an ecological time-series design utilized an everyday count of asthma emergency visits from 2007 to 2012 as the dependent variable.
• Independent variables air pollutants (NO2, PM2.5 CO, and O3), controlling for meteorological conditions, were examined utilizing time-series and Poisson GLM models.

Results

• They included total 76,651 emergency asthma visits with an average of 35 visits per day (SD = 9.2, range 11-80) in a stationary time series.
• Increased visit volume in fall and spring were not related to air pollutants.
• Relationship between individual air pollutants occurred in otherwise low-volume months for asthma emergency visits.
• The strongest relationship was an 11.6% increase in the asthma emergency visit rate amid the month of June.
• In monthly groupings that removed most of the autumn and spring months, O3, PM2.5, CO, and NO2 were related to 5, 4, 2, and 2% increases in asthma emergency visits, respectively.
• CO was the only pollutant with a negative relationship with asthma emergency visits, occurring in the month of April.