Best Available Control Technology

The federal Clean Air Act and Maricopa County Air Pollution Control Regulations Rule 241 (Minor New Source Review (NSR)) require the use of Best Available Control Technology (BACT) for sources that are either new sources or modifications to existing sources of air pollution that exceed the following emission thresholds:

• 40 or more tons/yr of volatile organic compounds (VOCs)
• 40 or more tons/yr of nitrogen oxides (NO_x)
• 40 or more tons/yr of sulfur dioxide (SO₂)
• 15 or more tons/yr of PM₁₀
• 100 or more tons/yr of carbon monoxide (CO)
• 10 or more tons/yr of PM_2.5
• 0.3 or more tons/yr of lead (Pb)

If a source is a new source or a source is making modifications that exceed these emission thresholds, it is the permit applicant’s responsibility to include a BACT analysis in their permit application and to propose BACT for their project. As part of the BACT analysis, the permit applicant may be required to conduct a survey to determine what methods, measures, or control technologies are available for emissions control. In some cases, alternative basic equipment, processes, and fuels must be considered in addition to emission control technologies and standards. The analysis must also include a justification of the permit applicant’s proposed BACT. 

BACT Clearinghouse

The Maricopa County Air Quality Department (MCAQD) BACT Clearinghouse specifies the BACT requirements that MCAQD has approved for commonly permitted sources subject to MCAQD Rule 241. The BACT Clearinghouse is for informational purposes only and serves as a guide for permit applicants and others interested in understanding emissions limits, control devices, and techniques needed to meet BACT. 

Permit applicants are encouraged to use the BACT Clearinghouse to ensure consistent and expeditious processing of permit applications where BACT is required. 

Permit applicants should review the BACT Clearinghouse to determine if BACT is available for their specific equipment or process. If the BACT Clearinghouse does not include or the permit applicant chooses not to propose a listed BACT control/reduction measure or an alternative measure that meets the emission thresholds, then the permit applicant has other options for meeting BACT requirements: 

• Agree to enforceable emission limits in their permit to avoid triggering BACT
• Use BACT for the same or similar source category listed by the South Coast Air Quality Management District (SCAQMD), the San Joaquin Valley Air Pollution Control District (SJVAPCD), or the Bay Area Air Quality Management District (BAAQMD)
• Complete a top-down BACT analysis customized for their equipment or facility

Access BACT Determinations >>  

For more information on BACT determinations, please consult the MCAQD Permitting Handbook or email Permit Engineering.