Hurricane Laura hit an area known for its refineries and chemical plants. They released millions of pounds of air pollution when they shut down, and many air monitors are not functioning.

A new study finds that the U.S. places with the most polluted air in the 1980s remain the most polluted today. Poor people and people of color are more likely to live in places with dirty air.

Transportation — trucks, trains, planes and automobiles — is a major source of greenhouse gas emissions in the U.S. Electric vehicles offer a less...