Search

EPA Revises National Ambient Air Quality Standard

Posted on 2/12/2024 by Nick Waldron

EPA finalized a rule on February 7, 2024, to tighten the annual national ambient air quality standard for fine particulate matter (PM2.5) by 25%*. EPA says the decision is based on available science and comments on its 2023 proposed rule. This week’s rule did not change the 24-hour standard for fine particulate matter or any other NAAQSs.

*The standard is lowering from 12 micrograms per cubic meter to 9 micrograms per cubic meter.

Back in December 2020, EPA finalized a rule to retain the National Ambient Air Quality Standard (NAAQS) for particulate matter—meaning, the Agency decided not to revise it.

See EPA's news release covering the rule.

Why make a rule without changes?

The Clean Air Act requires EPA to reevaluate the NAAQS standards every five years. In 2020, EPA determined that the rule did not need to change.

In 2021, the Agency said that it reconsidered the 2020 decision to retain the old standards because “the available scientific evidence and technical information indicated that the standards may not be adequate.” This led to the 2023 proposed rule and the subsequent final rule that we are seeing now.

What is fine particulate matter?

Fine particulate matter includes dust, dirt, soot, or smoke, and other particles that are “so small they can only be detected using an electron microscope.” For reference, the average human hair is 50–70 micrometers thick. These particles are 2.5 micrometers wide or smaller—significantly smaller, even, than the width of a human hair.

Some of these particles are a result of chemical reactions in the air, and others are emitted directly from construction sites, unpaved roads, fires, and other sources.

Exposure to particulate matter can negatively impact human health and the environment by affecting the lungs and heart, making lakes and streams acidic, affecting the diversity of ecosystems, damaging sensitive forests and farm crops, and more.

Complete Environmental Regulations Training

Want a clearer idea of how major EPA air, water, and chemical programs all fit together to affect your site's activities? Join in on the next Complete Environmental Regulations Webinar on March 14–15 at Lion.com.

EH&S professionals who attend can identify the regulations that apply to their facility and locate key requirements to achieve compliance with the Clean Air and Clean Water Acts to EPCRA, TSCA, Superfund, and more. Prefer to train at your own pace? Try the interactive online course.

Find a Post

Compliance Archives

Lion - Quotes

The instructor was great, explaining complex topics in terms that were easily understandable and answering questions clearly and thoroughly.

Brittany Holm

Lab Supervisor

Lion is at the top of the industry in compliance training. Course content and structure are updated frequently to make annual re-training enjoyable. I like that Lion has experts that I can contact for 1 year after the training.

Caroline Froning

Plant Chemist

Lion Technology workshops are amazing!! You always learn so much, and the instructors are fantastic.

Dorothy Rurak

Environmental Specialist

As always, Lion never disappoints

Paul Resley

Environmental Coordinator

I love that the instructor emphasized the thought process behind the regs.

Rebecca Saxena

Corporate Product Stewardship Specialist

The instructor created a great learning environment.

Avinash Thummadi

CAD & Environmental Manager

No comparison. Lion has the best RCRA training ever!!

Matt Sabine

Environmental Specialist

Having the tutorial buttons for additional information was extremely beneficial.

Sharon Ziemek

EHS Manager

The instructor was very knowledgeable and provided pertinent information above and beyond the questions that were asked.

Johnny Barton

Logistics Coordinator

Attending Lion Technology classes should be mandatory for every facility that ships or stores hazmat.

Genell Drake

Outbound Lead

Download Our Latest Whitepaper

What to do before, during, and after a RCRA hazardous waste inspection to defend your site from rising State and Federal penalties.

Latest Whitepaper

By submitting your phone number, you agree to receive recurring marketing and training text messages. Consent to receive text messages is not required for any purchases. Text STOP at any time to cancel. Message and data rates may apply. View our Terms & Conditions and Privacy Policy.