February 6, 2025
This interactive map shows where small industrial boilers contribute to unsafe air quality across the United States. Each shaded area on the map represents a county that does not meet the U.S. Environmental Protection Agency’s 2015 ozone standards, and the purple gradient depicts the quantity of small boilers (≤50 MMBtu/hr) in the county. These 174 counties can achieve cleaner air by adopting policies to accelerate installation of electric industrial technologies, such as industrial heat pumps. Additional discussion of this map and policy solutions is available in our blog post.
Click the labels in the bottom-right corner of the map to toggle between different views:
- Number of small industrial boilers in counties in nonattainment areas
- Industrial subsector distribution of the boilers within those counties, focusing on food and beverage, paper, refining, and chemicals
- Fuel type of the boilers within those counties (natural gas, oil products, coal, or other fuel types)
- Ozone classification
To view a full list of the counties we identified and the number of small boilers operating there, you can download our dataset.
Sources: We used Schoeneberger et al.’s boiler inventory (which we have found to be the most comprehensive and recent inventory) to locate boilers with capacities less than or equal to 50 million British thermal units per hour (MMBtu/hr) in counties in nonattainment areas, as defined by the Environmental Protection Agency (EPA) 8-hour ozone standards set in 2015.
