What is the PM10 to AQI Calculator?
This tool converts a PM10 (particulate matter up to 10 micrometers) concentration into the United States Air Quality Index (AQI) as defined by the US Environmental Protection Agency (EPA). It applies to the US AQI standard and uses the official EPA PM10 breakpoint table for a 24-hour average concentration measured in micrograms per cubic meter (µg/m³).
How to use it
Enter your 24-hour average PM10 concentration in µg/m³ and the calculator returns the corresponding AQI value (0–500) plus its health category — Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, or Hazardous. The supporting table shows which breakpoint segment was used.
The formula explained
The EPA uses piecewise linear interpolation. The concentration is first truncated to a whole number, then placed in the breakpoint band containing it. Within that band the AQI is computed as:
$$\text{AQI} = \frac{I_{hi} - I_{lo}}{C_{hi} - C_{lo}}\left(C - C_{lo}\right) + I_{lo}$$
where \(C\) is the truncated concentration, \([C_{lo}, C_{hi}]\) is the concentration band, and \([I_{lo}, I_{hi}]\) is the matching AQI band. PM10 bands include 0–54 µg/m³ (AQI 0–50), 55–154 (51–100), 155–254 (101–150) and higher.
Worked example
For PM10 = 200 µg/m³: it falls in the 155–254 band (AQI 101–150). $$\text{AQI} = \frac{150 - 101}{254 - 155}\times(200 - 155) + 101 = \frac{49}{99}\times 45 + 101 = 22.27 + 101 = 123.27,$$ rounded to 123 — category "Unhealthy for Sensitive Groups".
FAQ
Is this the US or international AQI? This uses the US EPA AQI scale and PM10 breakpoints. Other countries (e.g. India, China, EU) use different bands.
Why is my concentration truncated? EPA rules truncate PM10 to an integer µg/m³ before applying the formula.
What is the maximum AQI? This calculator caps at the 505–604 band (AQI up to 500); beyond that the EPA index is considered "beyond AQI".
