Thanks for your question in HCM.
 I can understand your concern
Asthma effects 5 to 8 % of population. 
Symptom can be precipitated  by 1.
cold air, 2.allergens like house dust mite, pollen, fur etc 3..infection,4. smoking and 
passive smoking, 5.pollution 6.Even by some drugs like ,  NSAIDs , beta- blockers..
 Symptoms may also increase in 7.early morning and 8. in contact with pets/carpets/feather pillows/ duvet/ floor cushions and other soft furnishings..
So you should avoid such precipitant factor as much as possible.
Hope I have solved your query.
Wish you good health thanks.
Thanks.