Esther Bejarano's son was 11 months old when asthma landed him in the hospital. She didn't know what had triggered his symptoms — neither she nor her husband had asthma — but she suspected it was the pesticides sprayed on the agricultural fields near her family's home.

Pesticides are a known contributor to asthma and are commonly used where Bejarano lives in California's Imperial Valley, a landlocked region that straddles two counties on the U.S.-Mexico border and is one of the main producers of the nation's winter crops. It also has some of the worst air pollution in the nation and one of the highest rates of childhood asthma emergency room visits in the state, according to data collected by the California Department of Public Health.

Bejarano has since learned to manage her now-19-y

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