EPA AQI from concentration API

Converts a raw pollutant concentration (PM2.5, PM10, O3, CO, SO2, NO2) into the US EPA Air Quality Index via the official piecewise-linear breakpoint interpolation with EPA truncation rules, returning category and color. Answers 'What AQI is 35.5 ug/m3 of PM2.5?', 'Which color band is this pollution?'.

Price$0.04per request

MethodPOST

Route/v1/climate/epa-aqi

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

aqiair-qualityepapm25ozonepollutionbreakpointconcentration

API URLhttps://x402.hexl.dev/v1/climate/epa-aqi

Integration docs

Example request

{
  "pollutant": "pm25",
  "concentration": 35.5
}

Example response

{
  "pollutant": "pm25",
  "concentration": 35.5,
  "truncatedConcentration": 35.5,
  "unit": "µg/m³",
  "aqi": 101,
  "category": "Unhealthy for Sensitive Groups",
  "color": "orange",
  "breakpoint": {
    "cLo": 35.5,
    "cHi": 55.4,
    "iLo": 101,
    "iHi": 150
  },
  "interpretation": "PM25 35.5 µg/m³ → AQI 101 (Unhealthy for Sensitive Groups).",
  "formula": "US EPA piecewise-linear AQI: I = (iHi−iLo)/(cHi−cLo)·(C−cLo) + iLo"
}

Input schema

{
  "type": "object",
  "required": [
    "pollutant",
    "concentration"
  ],
  "properties": {
    "pollutant": {
      "type": "string",
      "description": "One of pm25, pm10, o3, co, so2, no2",
      "examples": [
        "pm25"
      ]
    },
    "concentration": {
      "type": "number",
      "description": "Raw concentration (pollutant-specific units)",
      "examples": [
        35.5
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}