Air Quality Index Calculator
Calculate AQI from PM2.5, PM10, or Ozone concentrations. Get your air quality category, health advisory, and recommendations for exercise, masks, and vulnerable populations.
μg/m³
AQI Value
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AQI Category —
Health Advisory —
Mask Recommendation —
Extended More scenarios, charts & detailed breakdown ▾
μg/m³
PM2.5 AQI
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Category —
Health Advisory —
Exercise Guidance —
Professional Full parameters & maximum detail ▾
Overall
Overall AQI (Dominant Pollutant) —
Dominant Pollutant —
AQI Category —
Individual Pollutant AQIs
PM2.5 AQI —
PM10 AQI —
Ozone AQI —
CO AQI —
SO₂ AQI —
NO₂ AQI —
Advisory
Health & Mask Advisory —
How to Use This Calculator
- Enter your PM2.5 concentration in μg/m³ (micrograms per cubic meter).
- The calculator converts it to an AQI value and shows the category and health advisory.
- Use the PM10 and Ozone tabs to calculate AQI for other pollutants.
- The Professional tab calculates all pollutants at once and identifies the dominant pollutant.
Formula
AQI = ((AQI_High − AQI_Low) / (BP_High − BP_Low)) × (Cp − BP_Low) + AQI_Low
Where Cp = pollutant concentration, BP = concentration breakpoints from EPA tables.
Example
Example: PM2.5 = 35.5 μg/m³ → AQI breakpoints: 12.1-35.4 (Good-Moderate). AQI = ((100−51)/(35.4−12.1)) × (35.5−12.1) + 51 ≈ 101 (Unhealthy for Sensitive Groups).
Frequently Asked Questions
- The Air Quality Index (AQI) is a scale from 0-500 used by the EPA to communicate how polluted the air is. AQI 0-50 is Good, 51-100 is Moderate, 101-150 is Unhealthy for Sensitive Groups, 151-200 is Unhealthy, 201-300 is Very Unhealthy, and 301-500 is Hazardous.
- AQI is calculated using breakpoint tables. For PM2.5: AQI = ((AQI_high − AQI_low) / (BP_high − BP_low)) × (concentration − BP_low) + AQI_low. Each pollutant has different concentration breakpoints defined by the EPA.
- Health experts generally recommend N95 or higher respirators when AQI exceeds 150 (Unhealthy). At this level, PM2.5 concentrations exceed approximately 55 μg/m³. Surgical masks offer minimal protection against fine particles.
- The overall AQI is determined by the highest AQI among all measured pollutants on a given day. This "dominant pollutant" drives the overall index and health advisory.
- Indoor air can be 2-5 times less polluted than outdoor during high AQI events if windows are closed and air filtration (HEPA) is used. During wildfire smoke events, staying indoors with good filtration dramatically reduces exposure.