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Purpose: Social status influences asthma morbidity but the mechanisms are not well understood. To determine if sociodemographics influence the susceptibility to ambient aeroallergens, we determined the association between daily hospitalizations for asthma and daily concentrations of ambient pollens and molds in 10 large Canadian cities., Methods: Daily time-series analyses were performed and results were adjusted for day of the week, temperature, barometric pressure, relative humidity, ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Results were then stratified by age, gender, and neighborhood family education and income., Results: There appeared to be age and gender interactions in the relation between aeroallergens and asthma. An increase in basidiomycetes equivalent to its mean value, about 300/m3, increased asthma admissions for younger males (under 13 years of age) by 9.3% (95% CI, 4.8%, 13.8%) vs. 4.2% (95% CI, - 0.1%, 8.5%) for older males. The reverse was true among females with increased effect in the older age group: 2.3% (95% CI, 1.2%, 5.8%) in those under 13 years vs. 7.1% (95% CI, 4.1%, 10.1%) for older females. Associations were seen between aeroallergens and asthma hospitalization in the lowest but not the highest education group., Conclusions: Our results suggest that younger males and those within less educated families may be more vulnerable to aeroallergens as reflected by hospitalization for asthma.

Study Objectives: To document the existence and investigate the etiology of "thunderstorm asthma," which has been reported sporadically over the past 20 years., Design: We assessed the relationship between thunderstorms, air pollutants, aeroallergens, and asthma admissions to a children's hospital emergency department over a 6-year period., Results: During thunderstorm days (n = 151 days) compared to days without thunderstorms (n = 919 days), daily asthma visits increased from 8.6 to 10 (p < 0.05), and air concentrations of fungal spores doubled (from 1,512 to 2,749/m(3)), with relatively smaller changes in pollens and air pollutants. Daily time-series analyses across the 6 years of observation, irrespective of the presence or absence of thunderstorms, demonstrated that an increase in total spores, equivalent to its seasonal mean, was associated with a 2.2% (0.9% SE) increase in asthma visits., Conclusions: Our results support a relationship between thunderstorms and asthma, and suggest that the mechanism may be through increases in spores that exacerbate asthma. Replication in other climates is suggested to determine whether these findings can be generalized to other aeroallergen mixes.