EPA Proposes Amendments to Exceptional Events Regulations for Ozone [US]

On November 19th, 2015, the Environmental Protection Agency (EPA) announced a proposed rule to amend the Clean Air Act regulations that excuse spikes of ground-level ozone.

Attainment ornonattainment areas

Under 40 CFR Part 50 of the Clean Air Act regulations, state air monitoring data generated from “exceptional events” are excluded from EPA’s determination of whether to designate an area as “attainment” or “non-attainment.”

This labelling indicates whether the area complies with the National Ambient Air Quality Standard for ozone.

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Reasons for ozone surges

These proposed amendments would make it easier for states to prove that certain ground-level ozone surges are due to exceptional events, such as natural forces and not human activity.

The EPA has also announced the availability of a draft version of a guidance document entitled: “Draft Guidance on the Preparation of Exceptional Events Demonstrations for Wildfire Events that May Influence Ozone Concentrations.”

The proposed rule

The proposal follows the EPA’s new national ambient air quality standard for ground-level ozone, which lowered the standard from 75 parts per billion to 70 parts per billion and was finalized on October 1st, 2015.

The EPA is accepting public comments on the proposed exceptional event regulations and on the draft guidance until January 19th, 2016.  In addition, a public hearing will be held on December 8, 2015.

Red-on-line EHS Legalist


Proposed Rule: Treatment of Data Influenced by Exceptional Events, Federal Register, 80 FR 72839, November 19th, 2015.

Sharon Montazeri, U.S. EPA Finalizes Lower Ozone Standard of 70 ppb, Red-on-line USA, October 2nd, 2015.

40 CFR 50

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