The effects of air pollution on asthma hospital admissions in Adelaide, South Australia, 2003–2013 : time series and case-crossover analysis

We read with great interest the recent study by Chen and colleagues [1] which showed an increased risk of asthma hospital admissions in all age groups with total pollen. However, there are numerous issues that have been over-looked in the analysis of the pollen variable. If these issues were considered, the authors may have observed stronger species-specific effects, thereby contributing to the evidence base on which pollen species is the major trigger of asthma exacerbations requiring hospitalization