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Canadian Journal of Public Health = Revue Canadienne de Santé Publique logoLink to Canadian Journal of Public Health = Revue Canadienne de Santé Publique
. 2011 Jan 1;102(1):35–41. doi: 10.1007/BF03404874

The Population Attributable Fraction of Asthma Among Canadian Children

Elinor Simons 17,✉, Teresa To 17, Sharon Dell 17,27
PMCID: PMC6974220  PMID: 21485964

Abstract

Objective

We calculated the population attributable fraction (PAF) of Canadian childhood asthma due to modifiable environmental exposures, in order to estimate their relative contributions to asthma development based on the current literature.

Methods

We conducted a systematic review to determine Canadian childhood asthma incidence, Canadian prevalence of exposure to airborne pollutants and indoor allergens, and international estimates of the risk of developing physician-diagnosed asthma (PDA) associated with each exposure. Combining risk estimates by meta-analysis where possible, PAF was calculated by the formula: Inline graphic

Synthesis

Age-specific Canadian childhood asthma incidence ranged from 2.8%-6.9%. Canadian exposure prevalences were: PM10 16%, PM2.5 7.1%, NO2 25%, environmental tobacco smoke (ETS) 9.0%, cat 22%, dog 12%, mouse 17%, cockroach 9.8%, dust mite 30%, moisture 14% and mould 33%. Relative risk estimates of PDA were: PM10 1.64, PM2.5 1.44, NO2 1.29, ETS 1.40, mouse 1.23, cockroach 1.96, and spanned 1.00 for cat, dog, dust mites, moisture and mould. PAF estimates for incident asthma among preschool children were: PM10 11%, PM2.5 1.6%, NO2 4.0%, ETS 2.9%, mouse 6.5% and cockroach 13%.

Conclusions

This systematic review suggests contributions to childhood asthma development from exposure to particulates, NO2, ETS, mouse and cockroach. The associations appeared to be more complex for cat, dog and dust mite allergens and more variable for mould and moisture. Additional prospective, population-based studies of childhood asthma development with objectively-measured exposures are needed to further quantify these associations.

Key words: Asthma, children, population attributable fraction, environmental exposure

Footnotes

Conflict of Interest: None to declare.

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