AQI Breakpoints Reference Table
| AQI Range |
Category |
PM2.5 (Āµg/mĀ³) |
Who’s Affected |
| 0ā50 | Good | 0.0ā12.0 | No impact |
| 51ā100 | Moderate | 12.1ā35.4 | Unusually sensitive |
| 101ā150 | Unhealthy for Sensitive | 35.5ā55.4 | Children, elderly, asthma |
| 151ā200 | Unhealthy | 55.5ā150.4 | Everyone |
| 201ā300 | Very Unhealthy | 150.5ā250.4 | Everyone ā health alert |
| 301ā500 | Hazardous | 250.5ā500.4 | Everyone ā emergency |
What is the formula to convert PM2.5 to AQI?
The US EPA uses a piecewise linear interpolation formula: AQI = ((AQI_high ā AQI_low) Ć· (C_high ā C_low)) Ć (C ā C_low) + AQI_low. Where C is the PM2.5 concentration and the breakpoints are defined by EPA for each pollutant category.
Is PM2.5 or PM10 more dangerous?
PM2.5 is considered more dangerous because its smaller particle size (under 2.5 micrometres) allows it to penetrate deep into the alveoli and enter the bloodstream. PM10 particles are filtered more effectively by the upper respiratory tract. However, both are regulated pollutants with established health thresholds.
What PM2.5 level is safe for jogging?
Below 12 Āµg/mĀ³ (AQI 50) is ideal for all outdoor activity. Up to 35.4 Āµg/mĀ³ (AQI 100) is generally acceptable. Above 55.4 Āµg/mĀ³ (AQI 150), prolonged vigorous outdoor exercise is not recommended even for healthy adults.
Who developed the AQI scale?
The US Environmental Protection Agency (EPA) developed the AQI scale. It consolidates measurements of five major air pollutants ā PM2.5, PM10, ground-level ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide ā into a single 0ā500 number with colour-coded categories.