EPA gives final approval to Maricopa County rule letting fleet owners earn pollution credits for cleaner trucks

The U.S. Environmental Protection Agency has signed off on a Maricopa County air quality rule that turns cleaner trucks into a commodity businesses can trade.

The county announced Thursday that the EPA gave final approval to Rule 205, which lets fleet owners and operators earn emission reduction credits when they replace or upgrade higher-emitting on-road vehicles.

Companies that want to build or expand industrial sites can use those credits to offset their own emissions and satisfy the federal Clean Air Act's permitting program for areas that do not meet air quality standards. The county says it can begin issuing credits right away.

The Board of Supervisors adopted the rule in May 2025. Like other local air rules, it could not take full effect until the EPA approved it as part of the state's air quality plan. The EPA proposed approval in April, and a public comment period followed.

County Air Quality Director Philip McNeely told KJZZ in October that the rules were already on the books but were "really not effective in terms of creating" credits without federal approval. The rule covers reductions of nitrogen oxides and volatile organic compounds, the pollutants that form ground-level ozone.

A second rule is pending

A companion measure, Rule 204, would do the same for non-road equipment such as locomotives and construction machinery. The EPA proposed approving it about a month ago, and it has not received final approval.

County leaders say the approach rewards businesses instead of penalizing them. "By incentivizing rather than punishing job creators, this approach will deliver measurable improvements in air quality while creating new opportunities for businesses to invest and expand," Board Chair Kate Brophy McGee said in the announcement. Vice Chair Debbie Lesko praised EPA Administrator Lee Zeldin for his agency's cooperation with the county.

The county calls the two rules the first of their kind in the country. The county's announcement did not estimate the expected emission reductions, and no environmental group comment on the final approval had surfaced as of Friday.

Sources

maricopa.gov

kjzz.org