Does asthma crop up more on the farm?

The results of a recent study of the epidemiology of asthma may come as a surprise to some of our readers. Reporting in the Annals of Allergy, Asthma & Immunology, Vanderbilt University researchers found that, among 117,000 Tennessee children on Medicaid, the incidence of asthma was slightly higher among rural children, compared to their urban counterparts (13 percent versus 11 percent, respectively). Though the reason for this difference is not clear, the researchers believe maternal smoking could be a factor. They found that the mothers of 35 percent of rural children smoked during pregnancy, compared with the moms of 16 percent of urban children. Meanwhile, 22 percent of rural kids had bronchiolitis as infants, versus 17 percent of urban kids.

That maternal smoking — even during pregnancy — is a factor in infant development of asthma is nothing new to ACSH, whose 2003 edition of Cigarettes: What the Warning Label Doesn't Tell You includes this finding.

ACSH’s Dr. Josh Bloom is cautious about interpreting these data, since the differences are so small. “But, assuming there really is a difference in rural and urban incidences, this could simply reflect additional exposure to natural asthma-triggering allergens, such as pollen, in rural areas."