A new study has found a connection between electromagnetic fields (EMFs) and asthma – and could reignite the controversy about the safety of electronics and power lines. Lead study author Dr. De-Kun Li followed pregnant women and their children for up to 13 years to assess the possible effects of magnetic fields on health. The women wore a meter during pregnancy to measure their exposure to magnetic fields, which are emitted by everything from microwaves and vacuums to power lines. About 20 percent of the 626 children born were eventually diagnosed with asthma. Li found that women exposed to the highest levels of exposure to EMFs had a 3.5-fold increased risk of having a child who would later be diagnosed with asthma, compared to women with lower exposure levels.