
How Pollutants Affect Wheezing and Childhood Asthma, a lecture by Dr David Bernstein:
Traffic related air pollutants (TRAPs) are products of combustion of gasoline and diesel, NO2, ozone, and particulate matter from diesel exhaust vehicles. Fine and ultrafine particles are the most problematic.
Particulates induce reactive oxygen species and therefore oxidative stress. It overwhelms antioxidant defenses (such as glutathione). TRAPs can cause significant health effects even in healthy subjects.
Buses and trucks are the worst offenders, TRAPs-wise. This puts children living near highways at higher risk of allergy/asthma.
Diesel exhaust particles (DEP) enhance specific IgE/Th2 immune responses in the nose and augments sensitization to a neoantigen - they act as an adjuvant.
Living close to highways is associated with atopic sensitization. Hypothesis: proximity to traffic source directly correlates with allergic sensitization in high risk infants with atopic parents.
TRAPs can exacerbate existing asthma.

Inflammation in asthma (click to enlarge the image).