The generally weaker interactions of cat ownership with air pollution and the absence of an effect of air pollution among children with only a cat in the home suggest that allergen exposure may be less likely to be responsible for the observed effects than endotoxin.
"We think it's probably not allergy to dogs, otherwise we would expect to see an effect of air pollution with cats," said Dr. Rob S. McConnell, the lead author of the study and professor of preventive medicine at the University of Southern California.
Evidence of an effect of air pollution on blood pressure is increasing (Brook et al. 2010).
Several hypothesized mechanisms support biologic plausibility of an effect of air pollution on preterm birth.
In summary, overall the results of this large cohort study of female nurses do not support an effect of air pollution on PD risk.
Potential biologic mechanisms behind this association may involve an effect of air pollution on the placenta, embryo, maternal immunologic system, ovarian hypothalamic axis, and the induction of IUGR, which can lead to a more vulnerable fetus.
A variety of hypothesized pathways have been implicated in human and animal studies, including an effect of air pollution on endothelial function and vascular tone, autonomic function, thrombosis, blood pressure, and oxidative stress.
In this study, we observed evidence of an effect of air pollution on pregnancy outcomes, specifically the association of PM2.5 concentrations in the first month of pregnancy and LBW.
In addition, human experimental (Mills et al. 2007) and epidemiologic (Chuang et al. 2008) studies have demonstrated an effect of air pollution on ST-segment changes in electrocardiograms indicating the triggering of acute ischemia.
The suggested modification by fruit intake of an effect of air pollution on the risk for lung cancer might similarly be explained by the presence of oxidants and prooxidants in air pollution (Borm et al. 2004; Moller et al. 2010), which might lead to a higher risk for lung cancer mainly in individuals with low intake of antioxidants in fruits.
