Question of the Week: Hazardous Air Pollutants: Part 61 vs. Part 63
Q. What is the difference between the “original” National Emissions Standards for Hazardous Air Pollutants (NESHAPs) of 40 CFR 61 and the “new” NESHAPs of 40 CFR 63?
A. Congress, through the Clean Air Act (CAA) of 1970, required the EPA to identify Hazardous Air Pollutants (HAP) and promulgate standards for each HAP. Between 1971 and 1990, the EPA published emissions standards for each identified HAP in Part 61. But, in almost twenty years, the Agency only identified eight HAPs (asbestos, benzene, beryllium, coke oven emissions, inorganic arsenic, mercury, radionuclides, and vinyl chloride).
This pace was too slow for Congress, so as part of the Clean Air Act Amendments of 1990, they added a list of 189 HAPs to Section 112 of the CAA and gave EPA a specific schedule to issue final standards on sources of HAPs. Most of these Congressionally mandated HAPs were volatile organic compounds or toxic heavy metals.
That’s the history. What’s the difference in the standards themselves?
Standards in Part 61 apply based on the activity you are doing and what hazardous air pollutants that may emit (for example: demolition and renovation of old buildings may emit asbestos or fugitive emissions of benzene from storage tanks). If you are performing an activity identified in Part 61, you must perform whatever actions or implement whatever controls are required for that type of source to reduce your HAP emissions. If you do not perform any of the activities identified in Part 61, then Part 61 does not apply to you. [40 CFR 61.01(c)]
The more than 100 standards in Part 63 apply based on the industrial classification of your facility, not to specified activities, and are further broken down with alternative standards for “major sources” and “area sources.” [40 CFR 63.1(b)(1)]
A major source is one that emits or has the potential to emit ten (10) tons per year or more of any single HAP, or 25 tons per year or more of any combination of HAP (for example: lead smelters, dry cleaners, pulp and paper production). Major sources are supposed to use Maximum Achievable Control Technology (MACT) in order to reduce their HAP emissions.
An area source is a facility that does not emit enough HAP to be a major source, but is specifically identified by the EPA in Part 63. Area sources are supposed to use Generally Available Control Technology (GACT) to control their HAP emissions. GACT is generally considered to be a less burdensome requirement than MACT.
If your facility is not a major source of HAPs, and is not specifically identified in Part 63 as an area source, then Part 63 does not apply to you.
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