Yuma PM-10 Moderate Nonattainment Area Rulemaking


The Yuma PM-10 (particulate matter 10 microns or less in diameter) Moderate Nonattainment Area (NAA) is at risk of being reclassified as a PM-10 Serious Nonattainment Area, which would require additional and costly controls that could affect Yuma’s economy. Because the Yuma NAA is currently designated as moderate, new and amended regulations will have to comply with requirements for reasonable available control measures (RACM) with a goal to achieve attainment and reduce burdens while improving health. Continued nonattainment may prompt EPA to reclassify Yuma as a serious nonattainment area and then controls will have to comply with requirements for best available control measures (BACM), which are more stringent than RACM and likely more expensive and burdensome. New major stationary sources applying for an air quality permit in the Yuma area would be required to install control technology with the lowest achievable emission rate (LAER) and acquire costly emission credits to offset new PM-10 emissions. In a moderate NAA the threshold for new major sources is 100 tons of PM-10 per year, but in a serious NAA the threshold drops to 75 tons per year.

To avoid reclassification, EPA must concur with ADEQ’s exceptional event demonstrations that provide detailed proof and evidence that an exceedance of the PM-10 standard was due to an exceptional event, like a dust storm. The Federal Exceptional Events Rule only allows EPA to review an exceptional event demonstration if ADEQ has EPA (federally) approved regulations for PM-10 in the Yuma NAA, which ADEQ does not currently have.

The new/amended rules will reduce emissions of PM-10, improve air quality, and protect human health. Once implemented and federally approved, they will allow for the development of exceptional event demonstrations that will help the area move forward toward redesignation to attainment.