EPA Air Quality: National Summary for 2023: Analysis

     The annual EPA Air Quality National Summary includes air quality trends, emissions trends, and weather influence. The data clearly shows improvements in nearly all ambient air pollutants in the most recent trend from 2010-2023. EPA notes:

“These estimates are based on actual monitored readings or engineering calculations of the amounts and types of pollutants emitted by vehicles, factories, and other sources. Emission estimates are based on many factors, including levels of industrial activity, technological developments, fuel consumption, vehicle miles traveled, and other activities that cause air pollution.”

Input from state and local air quality agencies, tribes, and industry is used to get the data. Percent changes in air quality are shown below. I made two graphs from the data to show the same information graphically, one for 2010-2023 and one for 2000-2023.

     The next table shows the percent changes in emissions. Similarly, I made two graphs from the data, one for 2010-2023 and the other for 2000-2023. The emissions data shows changes in VOC emissions as well as the six criteria pollutants.

“Emissions of air pollutants continue to play an important role in a number of air quality issues. In 2023, about 66 million tons of pollution were emitted into the atmosphere in the United States. These emissions mostly contribute to the formation of ozone and particles, the deposition of acids, and visibility impairment.”

     The graph below shows some interesting, important, and optimistic trends. It is clear that the aggregate emissions from the six criteria pollutants (lead, carbon monoxide, nitrogen oxides, sulfur dioxide, PM 2.5, and ozone) have thoroughly decoupled from GDP, vehicle miles traveled, and population. Energy consumption and CO2 emissions have also decoupled from GDP, vehicle miles traveled, and population, but not as much as the air pollutants. There are several reasons for the reductions in air pollutants including the retiring of more coal-fired power plants which reduced sulfur dioxide, PM, and NOx, and some of the other criteria pollutants. This increase in the retiring of these plants was made possible in large part due to the wide low-cost availability of less-emitting natural gas to replace coal. That availability was enabled by advances in the upstream oil & gas industry such as high-volume hydraulic fracturing, horizontal drilling, and other associated technological and efficiency improvements in the industry. Tighter regulations also contributed to the decrease. It is a success story that should be told more often.

     The final graph below shows that there is still more work to be done to decrease air pollution since millions of people still live where air pollutants are present at high levels, particularly ozone and particulate matter.

     Finally, the EPA notes that the weather has a strong influence, particularly on the ozone and particulate matter that make up most of the air pollution problems faced today.

“Weather conditions influence emissions and air quality.  EPA has developed statistical approaches to account for weather’s influence on ozone and fine particles.  While these approaches do not change the quality of air we breathe, they do help us understand how well emission reduction programs are working.”

 

References:

 

Air Quality – National Summary. U.S. EPA. 2024. Air Quality - National Summary | US EPA