333. Would a listed toxic chemical present in compressed air be exempt? What if the listed toxic chemical is present in air emissions from a boiler?
A listed toxic chemical present in compressed air drawn from the environment would not have to be counted toward a threshold determination because it meets the intake air exemption (40 CFR Section 372.38(c)(5)). If that same listed toxic chemical is present in the boiler emissions air only because it was in the compressed air fed to the boiler, then it would remain exempt. However, if the listed toxic chemical is created as a result of combustion, you have coincidentally manufactured the toxic chemical and must consider it for reporting.