While most haze pollution does not originate in national parks, it can travel hundreds of miles from its source – coal plants, vehicles and oil and gas operations are the main culprits– harming the air we breathe, and the health of park visitors, wildlife and nearby communities.
In fact, nearly 90 percent of our more than 400 national parks are plagued by haze pollution. Utilizing a standard EPA calculation method, NPCA has identified polluting sources that are likely affecting Class I national parks and wilderness areas across the country. Here are the worst:
 This analysis is based on the Q/d metric where Q, in tons, are the emissions by a point source and d is the distance (in kilometers) from that point source to the nearest boundary of a Class I Area. The emissions data was obtained from the 2017 NEI for non EGUs and from the 2019 AMPD for EGUs.