Behind the asthma epidemic
It’s been observed that more and more cases of asthma have been reported over time:
The above chart is from this page of speculations about the causes of the increase. The page has many charts of data that show a rising pattern—that kind of chart is pretty commonly found, especially in a country whose population follows the same pattern (though the chart above corrects for population growth by showing the rate of incidence (per 1000) rather than the absolute number (which would grow as the population grows, other things being equal).
From The Week, another possible reason for the increase: more and more sources of low-frequency EMFs in the home and other places frequented by the pregnant:
Pregnant women with the highest exposure to low-frequency electromagnetic fields, or EMFs—which are generated by microwave ovens, vacuum cleaners, hair dryers, and other common electrical devices—were three times as likely to give birth to a child who later developed asthma as those with the lowest exposure, a Kaiser Permanente study found. “The problem with EMF is that you can’t see, smell it, you can touch it,” says study author De-Kun Li. But you should strive to “avoid those sources that we know about,” especially if you’re expecting.