3. Passive Smoking
Chilmonczyk used urine cotinine measurements as a biological marker of the exposure to tobacco smoke, and was able to demonstrate that acute exacerbations of asthma in children increase with exposure to second hand smoke.
http://www.theberries.ns.ca/BOTW_archives/passive_smoke.html

4. PCCU Volume 15
Although adults with asthma commonly report ETS exposure as a trigger for asthma exacerbation, the effect of exposure on adult asthma status has received less research. In samples drawn from different populations, ranging from clinical to...
http://www.chestnet.org/education/online/pccu/vol15/lessons1_2/lesson01.php

5. EPS 2nd hand smoke/children
ETS exposure is causally associated with additional episodes and increased severity of symptoms in children with asthma. This report estimates that 200,000 to 1,000,000 asthmatic children have their condition worsened by exposure to ETS.
http://www.nationalguild.com/library/ets_children.html