Skip to main content
Find a Lawyer

Code of Federal Regulations Title 40. Protection of Environment § 40.51.150 Classification of regions for episode plans

Current as of January 02, 2025 | Updated by Findlaw Staff

(a) This section continues the classification system for episode plans. Each region is classified separately with respect to each of the following pollutants:  Sulfur oxides, particulate matter, carbon monoxide, nitrogen dioxide, and ozone.

(b) Priority I Regions means any area with greater ambient concentrations than the following:

(1) Sulfur dioxide—100 μg/m3 (0.04 ppm) annual arithmetic mean;  455 μg/m3 (0.17 ppm) 24–hour maximum.

(2) Particulate matter—95 μg/m3 annual geometric mean;  325 μg/m3 24–hour maximum.

(3) Carbon monoxide—55 mg/m3 (48 ppm) 1–hour maximum;  14 mg/m3 (12 ppm) 8–hour maximum.

(4) Nitrogen dioxide—100 μg/m3 (0.06 ppm) annual arithmetic mean.

(5) Ozone—195 μg/m3 (0.10 ppm) 1–hour maximum.

(c) Priority IA Region means any area which is Priority I primarily because of emissions from a single point source.

(d) Priority II Region means any area which is not a Priority I region and has ambient concentrations between the following:

(1) Sulfur Dioxides—60–100 μg/m3 (0.02–0.04 ppm) annual arithmetic mean;  260–445 μg/m3 (0.10–0.17 ppm) 24–hour maximum;  any concentration above 1,300 μg/m3 (0.50 ppm) three-hour average.

(2) Particulate matter—60–95 μg/m3 annual geometric mean;  150–325 μg/m3 24–hour maximum.

(e) In the absence of adequate monitoring data, appropriate models must be used to classify an area under paragraph (b) of this section, consistent with the requirements contained in § 51.112(a).

(f) Areas which do not meet the above criteria are classified Priority III.

Previous Part of Code Next Part of Code
Back to Chapter List

Cite this article: FindLaw.com - Code of Federal Regulations Title 40. Protection of Environment § 40.51.150 Classification of regions for episode plans - last updated January 02, 2025 | https://codes.findlaw.com/cfr/title-40-protection-of-environment/cfr-sect-40-51-150/

FindLaw Codes may not reflect the most recent version of the law in your jurisdiction. Please verify the status of the code you are researching with the state legislature before relying on it for your legal needs.

Was this helpful?

Welcome to FindLaw's Cases & Codes

A free source of state and federal court opinions, state laws, and the United States Code. For more information about the legal concepts addressed by these cases and statutes, visit FindLaw’s Learn About the Law.

Go to Learn About the Law

Latest Blog Posts

For Legal Professionals

Learn About The Law

Get help with your legal needs

FindLaw’s Learn About the Law features thousands of informational articles to help you understand your options. And if you’re ready to hire an attorney, find one in your area who can help.

Go to Learn About the Law

Need to Find an Attorney?

Search our directory by legal issue

Enter information in one or both fields (Required)

Copied to clipboard