The air quality health index and asthma morbidity: a population-based study.
BACKGROUND
Exposure to air pollution has been linked to the exacerbation of respiratory diseases. The Air Quality Health Index (AQHI), developed in Canada, is a new health risk scale for reporting air quality and advising risk reduction actions.


OBJECTIVE
We used the AQHI to estimate the impact of air quality on asthma morbidity, adjusting for potential confounders.


METHODS
Daily air pollutant measures were obtained from 14 regional monitoring stations in Ontario. Daily counts of asthma-attributed hospitalizations, emergency department (ED) visits, and outpatient visits were obtained from a provincial registry of 1.5 million patients with asthma. Poisson regression was used to estimate health services rate ratios (RRs) as a measure of association between the AQHI or individual pollutants and health services use. We adjusted for age, sex, season, year, and region of residence.


RESULTS
The AQHI values were significantly associated with increased use of asthma health services on the same day and on the 2 following days, depending on the specific outcome assessed. A 1-unit increase in the AQHI was associated with a 5.6% increase in asthma outpatient visits (RR = 1.056; 95% CI: 1.053, 1.058) and a 2.1% increase in the rate of hospitalization (RR = 1.021; 95% CI: 1.014, 1.028) on the same day and with a 1.3% increase in the rate of ED visits (RR = 1.013; 95% CI: 1.010, 1.017) after a 2-day lag.


CONCLUSIONS
The AQHI values were significantly associated with the use of asthma-related health services. Timely AQHI health risk advisories with integrated risk reduction messages may reduce morbidity associated with air pollution in patients with asthma.
Child Health Evaluative Sciences, The Hospital for Sick Children, Toronto, Ontario, Canada. teresa.to@sickkids.ca
Teresa
T
To
Shixin
S
Shen
Eshetu G
EG
Atenafu
Jun
J
Guan
Susan
S
McLimont
Brian
B
Stocks
Christopher
C
Licskai
D000393:Air Pollutants / Q000633:toxicity*; D000397:Air Pollution / Q000009:adverse effects*; D001249:Asthma / Q000139:chemically induced* / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D052638:Particulate Matter / Q000633:toxicity*
D000393:Air Pollutants; D052638:Particulate Matter