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Threshold Limit

The threshold limit is the annual emission rate above which a company may need additional controls or review.

The threshold limit is the annual uncontrolled emission rate above which the company needs to either propose add-on controls (to meet Tier I BACT requirements) or perform a Tier III BACT review (economic reasonableness).

The threshold limits for non-halogenated organic compounds and water soluble inorganic compounds were determined by an internal TNRCC Tier I BACT review of all semiconductor permits issued in Texas since 1994.

The New Source Review Permits Division policy requires a PSD review for facilities proposing greater than 250 tons per year of halogenated organic compounds. Therefore, the threshold limit for halogenated organic compounds is set at 250 tons per year. With the Montreal Protocol and the Clean Air Act Amendment of 1990 phasing out halogenated compounds, we would not expect a company to propose significant amounts of this class of emissions.

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