If you work with children with Asthma or have children with Asthma this is a really interesting article published in the British Medical Journal in December 2014. As we know Childhood asthma is a complex condition “where many environmental factors are implicated in causation. The rapid rise in asthma during the 1980s and 90s was too abrupt to be explained solely by change in prevalence of genetic variations. Changing environmental exposures appear to be relevant to the high prevalence of asthma in the Western world.”
The article has captured all of the literature associating early environmental exposures and asthma development in children up to 9 years of age; this cut-off was chosen to avoid the effects of puberty and active smoking on asthma causation. There are some good tables which identify environmental associations which you may find particularly interesting.