Emissions from ships waiting to dock are beginning to affect the local environment.

Hundreds of cargo freighters are still waiting for their turn to dock at the ports of Los Angeles, California. The freighters have been idling off the coast for weeks now as the understaffed port workers try to get to every vessel and ship out their cargo to the rest of the country. Normally, when cargo ships need to idle like this, they would plug into power sources along the shoreline, allowing them to power down their engines. Due to the blockage, though, these ships have been forced to stay out on the water, leaving their engines running, and the emissions are starting to affect the local environment.

The diesel engines utilized by the ships have been ejecting potentially harmful particles into the air around the coast, lowering the air quality for California denizens. “We know that more particles make people more sick,” Suzanne Paulson, a professor in the Department of Atmospheric and Oceanic Sciences at the University of California, Los Angeles, told NBC News. “Diesel engines produce a lot of particulate and these diesel particles make people more sick than some other types of particles.”

“The area closer to the ports is predominantly lower income, people of color; there’s a large Latino population,” said Chris Chavez, deputy policy director for the Coalition for Clean Air. “It’s a frontline community and is one of the most polluted areas in the state. Constant exposure to pollution is something they live with day in and day out.”

The emissions and air quality are expected to worsen the long the supply chain problems last.