---
title: "EPA NAAQS Limits: PM2.5, PM10, O₃, CO | Aethair"
description: "US EPA National Ambient Air Quality Standards (NAAQS) limit values for PM2.5, PM10, Ozone, Carbon Monoxide, and more: every value and averaging period,…"
url: https://aethair.io/standards/epa_naaqs/
---

Compliance · US EPA

# US EPA National Ambient Air Quality Standards (NAAQS)

Ambient air: regulatory (USA)

The National Ambient Air Quality Standards (NAAQS) are the air-pollution limits set by the US Environmental Protection Agency under the Clean Air Act to protect public health and welfare across the United States. They cover six "criteria" pollutants: fine particulate matter (PM2.5), coarse particulate matter (PM10), ground-level ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. For each, the EPA sets **primary standards** to protect health (including sensitive groups such as children, the elderly, and people with respiratory disease) and **secondary standards** to protect crops, ecosystems, visibility, and materials.

[Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Configure EPA NAAQS Monitoring](https://aethair.io/build/?params=pm2_5,pm10,o3,co,no2,so2\&setting=outdoor)

At a glance

**US EPA** Ambient air: regulatory (USA)

6 parameters · 9 limit values

[PM2.5](https://aethair.io/parameters/pm2_5/) [PM10](https://aethair.io/parameters/pm10/) [Ozone (O₃)](https://aethair.io/parameters/o3/) [Carbon Monoxide (CO)](https://aethair.io/parameters/co/) [Nitrogen Dioxide (NO₂)](https://aethair.io/parameters/no2/) [Sulfur Dioxide (SO₂)](https://aethair.io/parameters/so2/)

1 device measures them all

- **Aethair PRO** Aethair O₃+NO₂ · Aethair CO (electrochemical) · Aethair MultiSense

[Official text from US EPA](https://www.epa.gov/criteria-air-pollutants/naaqs-table)

The standard

## What the NAAQS Are

The NAAQS are the reference point against which air quality is judged across the country, and the basis on which regions are declared to be in "attainment" or "nonattainment".

Limit values

## EPA NAAQS Limit Values

Every value US EPA publishes for the 6 parameters below, with its averaging period, as the standard states it.

[**PM2.5** Particulate Matter](https://aethair.io/parameters/pm2_5/)

**9 µg/m³** *Annual* 2024 primary

**35 µg/m³** *24-hour*

[**PM10** Particulate Matter](https://aethair.io/parameters/pm10/)

**150 µg/m³** *24-hour*

[**Ozone (O₃)** Gases & VOCs](https://aethair.io/parameters/o3/)

**0.07 ppm** *8-hour*

[**Carbon Monoxide (CO)** Gases & VOCs](https://aethair.io/parameters/co/)

**9 ppm** *8-hour*

**35 ppm** *1-hour*

[**Nitrogen Dioxide (NO₂)** Gases & VOCs](https://aethair.io/parameters/no2/)

**53 ppb** *Annual*

**100 ppb** *1-hour*

[**Sulfur Dioxide (SO₂)** Gases & VOCs](https://aethair.io/parameters/so2/)

**75 ppb** *1-hour*

Who it applies to

## Who Must Pay Attention

State and local air agencies are legally responsible for meeting the NAAQS through monitoring networks and State Implementation Plans. But the standards reach much further. Industrial facilities near their permit limits, developers whose projects must not tip a region into nonattainment, ports, airports, logistics hubs, and community groups tracking local exposure all measure against NAAQS values. Nonattainment carries real consequences (tighter permitting, mandated controls, and federal funding conditions), so credible monitoring matters commercially as well as legally.

Monitoring

## How Monitoring Demonstrates Compliance

Regulatory NAAQS compliance rests on Federal Reference Methods ([FRM](https://aethair.io/standards/epa_frm_fem/)) and Federal Equivalent Methods (FEM) operated in sited, quality-assured networks. Increasingly, agencies and private operators supplement these with dense networks of lower-cost sensors for spatial coverage, source identification, and public information, co-locating them against reference instruments for correction. A practical NAAQS-oriented deployment measures all six criteria pollutants together with meteorology, so that concentrations can be related to sources and weather.

A compliance station combines designated instruments, one per pollutant: a particulate monitor for PM2.5 and PM10, an ozone analyzer, and gas analyzers for CO, NO₂, and SO₂. For continuous monitoring alongside them, the recommended configuration below measures all six in one Aethair PRO: particulates with its built-in sensor and gases with cartridges.

[Customize this configuration](https://aethair.io/build/?params=pm2_5,pm10,o3,co,no2,so2\&setting=outdoor)

### Who measures each parameter

| Parameter | Aethair PRO | Aethair IAQ | External |
| - | - | - | - |
| [PM2.5](https://aethair.io/parameters/pm2_5/) | Built in | Built in | [3 instruments](https://aethair.io/parameters/pm2_5/) via Thiamis |
| [PM10](https://aethair.io/parameters/pm10/) | Built in | Built in | [3 instruments](https://aethair.io/parameters/pm10/) via Thiamis |
| [Ozone (O₃)](https://aethair.io/parameters/o3/) | O₃+NO₂ cartridge | — | [1 instrument](https://aethair.io/parameters/o3/) via Thiamis |
| [Carbon Monoxide (CO)](https://aethair.io/parameters/co/) | CO (electrochemical), MultiGas+ +1 cartridges | — | [3 instruments](https://aethair.io/parameters/co/) via Thiamis |
| [Nitrogen Dioxide (NO₂)](https://aethair.io/parameters/no2/) | NO₂, MultiSense +1 cartridges | — | [1 instrument](https://aethair.io/parameters/no2/) via Thiamis |
| [Sulfur Dioxide (SO₂)](https://aethair.io/parameters/so2/) | MultiSense, SO₂ cartridges | — | [1 instrument](https://aethair.io/parameters/so2/) via Thiamis |

Devices

## Devices That Cover EPA NAAQS

How much of this standard one Aethair monitor covers, followed by the third-party instruments in the sensor catalog that measure its parameters. Each connects to Environet through a Thiamis gateway, which adds whatever the monitor leaves out.

Aethair monitors

[**Aethair PRO** Built in + Aethair O₃+NO₂, Aethair CO (electrochemical), Aethair MultiSense Covers all 6](https://aethair.io/products/pro/)

Covers part of it (combine on one Thiamis)

[**RAE** Gas Detectors 3 of 6: CO, NO₂, SO₂](https://aethair.io/sensors/rae-gas-detectors/) [**TSI DustTrak** Particulate & Dust Monitors 2 of 6: PM10, PM2.5](https://aethair.io/sensors/tsi-particulate-dust-monitors/) [**Met One E-BAM** Particulate & Dust Monitors 2 of 6: PM10, PM2.5](https://aethair.io/sensors/met-one-particulate-dust-monitors/) [**Trolex** Particulate & Dust Monitors 2 of 6: PM10, PM2.5](https://aethair.io/sensors/trolex-particulate-dust-monitors/) [**TSI GM460** Gas Detectors 1 of 6: CO](https://aethair.io/sensors/tsi-gas-detectors/) [**RKI Instruments GX6000** Gas Detectors 1 of 6: CO](https://aethair.io/sensors/rki-instruments-gas-detectors/) [**2B Technologies POM** Specialty Air Analyzers 1 of 6: O₃](https://aethair.io/sensors/2b-technologies-specialty-air-analyzers/)

Solutions

## Solutions Judged Against EPA NAAQS

### [Outdoor Monitoring](https://aethair.io/solutions/outdoor-monitoring/)

Continuous outdoor air quality networks that sit alongside reference monitors

### [Perimeter Monitoring](https://aethair.io/solutions/perimeter-monitoring/)

Site boundary dust, silica, and noise compliance

### [Wildfire Air Monitoring](https://aethair.io/solutions/wildfires/)

Smoke plumes, black carbon, and community exposure

[All solutions](https://aethair.io/solutions/)

Article Library

## Articles on EPA NAAQS

### [Ambient Air Quality Monitoring: What Nonattainment Changes](https://aethair.io/resources/ambient-air-quality-monitoring/)

Ambient air quality monitoring explained: how PM2.5 attainment is measured, what a nonattainment designation triggers, and what site-level monitoring adds.

### [Wildfire Smoke Air Quality Monitoring: Detection & Response](https://aethair.io/resources/wildfire-smoke-air-quality-monitoring/)

Wildfire smoke monitoring for EHS and public health teams: real-time PM2.5, the AQI 151 respirator trigger, and how to alert workers before smoke arrives.

### [PM2.5 Exposure Limits & Monitoring: OSHA and NAAQS Standards](https://aethair.io/resources/pm25-monitoring-health-regulatory-guide/)

What are the OSHA and NAAQS exposure limits for PM2.5? Fine particulate thresholds explained, plus how continuous monitoring keeps workplaces compliant.

### [EHS Compliance Reporting Guide: Defensible, Audit-Ready Data](https://aethair.io/resources/ehs-compliance-reporting-guide/)

EHS compliance reporting needs defensible, audit-ready documentation. Build a workflow that holds up to OSHA and EPA audits and NAAQS benchmarks.

### [Ozone Exposure Limits and Monitoring: OSHA and NAAQS](https://aethair.io/resources/ozone-monitoring-exposure-limits/)

OSHA's ozone PEL is 0.1 ppm as an 8-hour TWA. How NIOSH, ACGIH, and the 70 ppb NAAQS compare, and why ozone needs short-interval monitoring.

### [Data Center Air Quality Monitoring, Inside and Out](https://aethair.io/resources/data-center-air-quality-monitoring/)

Data center air quality monitoring for operators: ISO 14644 cleanliness in the white space, construction dust, generator emissions, and perimeter noise.

[All articles](https://aethair.io/resources/)

Questions

## EPA NAAQS FAQ

What are the six criteria pollutants?

PM2.5, PM10, ground-level ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. Lead is also a NAAQS pollutant but is measured differently. These six are the ones a general ambient air-quality station targets, and each has primary (health) and secondary (welfare) standards.

What is the difference between attainment and nonattainment?

An area is in "attainment" when its measured concentrations meet a NAAQS and "nonattainment" when they exceed it. Nonattainment triggers stricter permitting, mandatory emission controls, and planning consequences, which is why accurate monitoring against the standards has direct regulatory and commercial weight.

Do low-cost sensors meet the NAAQS?

Formal compliance requires Federal Reference or Equivalent Methods in quality-assured networks. Lower-cost sensors are widely used alongside them for spatial coverage, source-finding, and public information, and are most reliable when co-located with a reference monitor and corrected. They complement rather than replace the regulatory instruments.

How do I build a NAAQS monitoring station?

For compliance data, combine a designated instrument for each pollutant with wind and weather sensors: a particulate monitor (PM2.5/PM10), an ozone analyzer, and gas analyzers (CO, NO₂, SO₂). For continuous monitoring, one Aethair PRO carries all six, and a Thiamis adds a weather station. Use the configurator to assemble and customize the configuration for your site.