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.
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.
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) 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.
Recommended
best match-
Industrial monitor for indoor and outdoor sites. Built-in sensors cover the essentials, and hot-swappable gas sensor cartridges and a differential-pressure option add more.
Built-inPM10PM2.5Gas 1
Aethair O₃+NO₂
Nitrogen Dioxide (NO₂)Ozone (O₃)Four-electrode electrochemical sensing measures oxidizing gases (ozone plus nitrogen dioxide) and reports one…
Gas 2
Aethair CO (electrochemical)
Carbon Monoxide (CO)An amperometric electrochemical CO cell with a solid, non-aqueous electrolyte (the long-life, low-power…
Also fits: Aethair MultiGas+, Aethair CO (ppb, four-electrode)
MultiSense
Aethair MultiSense
Sulfur Dioxide (SO₂)Simultaneous electrochemical detection of sulfur dioxide, nitrogen dioxide, and formaldehyde at…
Expansion
Free: differential pressure
Also measures 12 more
Dew PointHeat IndexRelative HumidityIlluminance / LightParticle Count (by size)PM1Total PM / Mass Conc.Barometric PressureEquivalent Continuous Level (Leq)Sound Pressure Level (SPL)Air TemperatureFormaldehyde (CH₂O)
Who measures each parameter
| Parameter | Aethair PRO |  Aethair IAQ |  External |
|---|---|---|---|
| PM2.5 | Built in | Built in | 3 instruments via Thiamis |
| PM10 | Built in | Built in | 3 instruments via Thiamis |
| Ozone (O₃) | O₃+NO₂ cartridge | — | 1 instrument via Thiamis |
| Carbon Monoxide (CO) | CO (electrochemical), MultiGas+ +1 cartridges | — | 3 instruments via Thiamis |
| Nitrogen Dioxide (NO₂) | NO₂, MultiSense +1 cartridges | — | 1 instrument via Thiamis |
| Sulfur Dioxide (SO₂) | MultiSense, SO₂ cartridges | — | 1 instrument 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
Covers part of it (combine on one Thiamis)
RAE Gas Detectors3 of 6: CO, NO₂, SO₂
TSI DustTrak Particulate & Dust Monitors2 of 6: PM10, PM2.5
Met One E-BAM Particulate & Dust Monitors2 of 6: PM10, PM2.5
Trolex Particulate & Dust Monitors2 of 6: PM10, PM2.5
TSI GM460 Gas Detectors1 of 6: CO
RKI Instruments GX6000 Gas Detectors1 of 6: CO
2B Technologies POM Specialty Air Analyzers1 of 6: O₃Solutions
Solutions Judged Against EPA NAAQS
Outdoor Monitoring
Continuous outdoor air quality networks that sit alongside reference monitors
Perimeter Monitoring
Site boundary dust, silica, and noise compliance
Wildfire Air Monitoring
Smoke plumes, black carbon, and community exposure
Article Library
Articles on EPA NAAQS
Ambient Air Quality Monitoring: What Nonattainment Changes
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
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
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
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
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
Data center air quality monitoring for operators: ISO 14644 cleanliness in the white space, construction dust, generator emissions, and perimeter noise.
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.
Monitor Against EPA NAAQS
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