Nice catch. I saw a related post yesterday saying the Mann et al. original paper lacked his raw data for peer review
It wouldn't be the first time the eviro-hucksters tried to withhold data. Was it an EPA study blaming midwest power plant particulates on asthma in the Eastern states that didn't reveal data? I think EPA said it was proprietary data of the contractor. What a load.
I'm not familiar with that study. However, I am very familiar with asthma, and I'm inclined to think that recent increases in the prevalence of asthma is due to more folks with a genetic predisposition for asthma. More minorities have asthma, and I believe the increase in the prevalence is due to changing demographics.
In support of my hypothesis, I maintain that folks who originally migrated to this country were more self selected to tolerate air pollution. Those folks had to endure miserable indoor air in the cold winters of the northern hemishere during the winter or freeze to death.
Recent immigration of people whose ancestors came from more tropical climates have respiratory systems whose genes were not selected for dealing with such pollution. It's indirect support for Darwin's theory of natural selection, but now invoking the theory of natural selection, which is the current explanation for evolution, is now politically incorrect.
Anyone doubting the demographic distribution of asthma is invited to go to PubMed, the website of the National Institute of Health, and use the following search strategy: asthma AND prevalence .