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Carbon Monoxide (CO)
Most of the change in CO emissions is driven by reductions in NEI onroad mobile sources in 2025 relative to the base, as seen in this plot showing the difference between January monthly total CO emissions from onroad mobile sources. Nonpoint O&G sources from the U.S. EPA NEI drive regional CO increases in Texas. Surveyed 3SAQS basin O&G sources drive the increases in NW New Mexico and NE Utah.
Nitrogen Oxides (NOx)
The NOx emissions changes are driven by similar sources as carbon monoxide. Diffuse and large U.S. EPA NEI onroad mobile source reductions in 2025 relative to the base can be seen in a plot of January total onroad mobile source NOx changes between 2025 and 2011.
Nonpoint U.S. EPA NEI O&G sources also drive regional NOX increases in Texas
. Surveyed 3SAQS O&G sources drive the NOx increases in NW New Mexico and NE Utah
Total Organic Gases (TOG)
Increases in future year TOG emissions are driven by oil and gas sources, particularly non-point O&G sources from the U.S. EPA NEI in Texas, Oklahoma, West Virgina, and western Pennsylvania
. Increases in future year TOG emissions are also seen in the surveyed 3SAQS O&G inventory in northeast Colorado and Wyoming
. Decreases in future year TOG emissions are primarily the result of reductions in TOG from onroad
mobile, although decreases in non-point O&G in southern Kansas
contrasts sharply with increasing emissions in the same sector just across the border in Oklahoma.
Projected increases in livestock NH3 emissions in the midwest and southeast
drive the regional increases in NH3. Emissions decreases in the West, Northeast, and Florida
are primarily from reductions in onroad mobile NH3. The changes in the NH3 emissions are driven by sources in the U.S. EPA NEI.
Sulfur Dioxide (SO2)
Elevated point sectors like EGU and non-EGU point are the largest sources of SO2 emissions. As these tile plots show low level emissions only, they do not reflect the future year emission changes due to the elevated source sectors. The reductions in low-level SO2 are due primarily to the nonpoint sector
. Reductions in fuel oil emissions in the Northeast and in stationary source coal combustion in the Southeast are reflected in these tile plots. Reductions in residual oil combustion drive the SO2 decreases seen in Utah. The increase in SO2 emissions northwest of Phoenix, Arizona is from cement manufacturing in Yavapai county. The projected SO2 emissions increase in west Texas
is from the U.S. EPA NEI non-point oil and gas sector.
Fine Particulate Matter (PM2.5)
Changes in PM emissions in the west are driven by increases in the U.S. EPA NEI fugitive dust sector
. While all sources of fugitive dust are projected to increase, unpaved road dust sources are projected to experience the largest increase across much of the west, leading to the PM2.5 emissions increases seen in New Mexico, Texas, Oklahoma, and Wyoming. The fugitive dust increases are offset by decreases in the onroad mobile sector
, as seen in the widespread PM2.5 emissions reductions in Colorado, California, and most of the East U.S.