People who suffer from asthma often say an attack feels like breathing through a pool of water or with a pillow covering their face.

In the United States, asthma is a bona fide public health epidemic: 17 million adults and 7 million children suffer from the disease. In thousands of severe cases, people die. Environmental triggers, like air pollution, can cause and exacerbate asthma—it’s critically important that we defend existing clean air protections and work for new ones.