It is noteworthy that we find negative effects of exposure to CO even at the low levels of ambient CO currently observed.
Some areas in our study saw a reduction in mean CO levels from 4 ppm to 1 ppm over our sample period.
Our estimates of the effects of CO on birth weight and gestation suggest that this reduction had an effect roughly equivalent to getting a women smoking 10 cigarettes a day to quit.
We also find that infants of smokers are at much greater risk of negative effects from CO exposure.
We also find some evidence of significant effects of PM10 and ozone on health at birth,particularly among smokers, though these estimates are less robust than our CO estimates.
We further find that a one unit decrease in mean CO levels in the first 2 weeks of life saves roughly 18 lives per 100,000 births, which represents a reduction in the probability of infant death of about 2.5%.