U.S. Environmental Protection Agency

Ambient air measurements: EPA AQS

Access ambient monitoring data with station and quality-assurance information.

Read the primary source

Dataset guide · U.S. Environmental Protection Agency

Read with context.

Select pollutant, monitor and averaging period. Check completeness, units and quality flags; use AirData for public extracts and documentation.

Before using a figure in advocacy, record the exact table or measure, geography, observation period, population, denominator and uncertainty. This page is a research guide; it does not claim that raw data have been imported or independently analyzed.

Limits to keep in view

AQS is not a real-time emergency alert service. Monitor coverage is uneven, and a station is not a measurement of every resident’s personal exposure.

Connect evidence to action

Choose a question, verify the relevant jurisdiction, and explain the action you are asking someone to take. A source-backed draft is a starting point—not a message sent on your behalf.

Use this in an advocacy brief

Research sources

Source text supports this summary. Human editorial approval, service availability and eligibility are separate checks.

Related policy & program records

Shared topic, not a claim of causation or eligibility.

Your working notes

Keep the context with the claim.

Write the question first

What are you trying to understand? Identify the population and place before looking for a number that might support your position.

Capture the measure

Record the source title, table or indicator, units, reference period and any stated uncertainty. Preserve the original wording of technical definitions.

Distinguish observation from explanation

A difference between groups can prompt further inquiry. It does not, by itself, identify the cause or establish the effect of a particular policy.