Triggers of asthma attacks in adults

131 adult asthma patients were enrolled into a study that assessed asthma triggers via a questionnaire.

Regardless of asthma severity, 59.5 % of the subjects reported to be triggered by more than 10 factors.

The most common triggers were air pollutants (89%) and weather changes (82%).

In the severe group, more frequently mentioned triggers were medications, emotional stress, weather changes and indoor pollutants. Stress was reported more frequently by females than males.

References:
Triggers in adult asthma: are patients aware of triggers and doing right? Göksel O, Celik GE, Oner Erkekol F, Güllü E, Mungan D, Misirligil Z. Allergol Immunopathol (Madr). 2009 May-Jun;37(3):122-8.
Air pollution near the home increases asthma severity in children
Traffic exposure associated with decreased lung function in asthma

The burden of adult asthma in the United States: patients with asthma less likely to be employed (odds ratio, 0.78) http://goo.gl/eCNuu
Image source: Interstate 80, seen here in Berkeley, California, is a freeway with many lanes and heavy traffic, Wikipedia, GNU Free Documentation License.