Particulate Concentration Calculator Formula
Understand the math behind the particulate concentration calculator. Each variable explained with a worked example.
Formulas Used
Estimated AQI
aqi_estimate = round(pm25_ugm3 * 500 / 500.4)AQI (linear approx 0-50 range)
aqi_linear_low = round(pm25_ugm3 * 50 / 12)Concentration in mg/m³
mg_m3 = pm25_ugm3 / 1000Variables
| Variable | Description | Default |
|---|---|---|
pm25_ugm3 | PM2.5 Concentration(ug/m³) | 35 |
How It Works
Particulate Matter and Air Quality
PM2.5 refers to fine particles smaller than 2.5 micrometers. These penetrate deep into the lungs and are the most health-relevant air pollutant.
AQI Estimation
AQI = PM2.5 (ug/m³) x 500 / 500.4
This is a simplified linear approximation. The actual EPA AQI uses piecewise breakpoints. Generally, 0-12 ug/m³ is Good (AQI 0-50), 12-35.4 is Moderate (51-100), and above 55.4 is Unhealthy (151-200).
Worked Example
The local air quality monitor reads 35 ug/m³ PM2.5.
- 01Simplified AQI = 35 x 500 / 500.4 = 35 (approximately)
- 02Linear low-range AQI = 35 x 50 / 12 = 146
- 03In mg/m³ = 35 / 1000 = 0.035 mg/m³
- 04This falls in the Unhealthy for Sensitive Groups range
Frequently Asked Questions
What is PM2.5?
PM2.5 stands for particulate matter with a diameter of 2.5 micrometers or less. Sources include vehicle exhaust, industrial emissions, wildfires, and cooking.
What PM2.5 level is safe?
The WHO guideline is an annual mean below 5 ug/m³ and a 24-hour mean below 15 ug/m³. The US EPA standard is an annual mean of 9 ug/m³.
How does PM2.5 affect health?
Long-term exposure increases risks of heart disease, stroke, lung cancer, and respiratory illness. Even short-term spikes can trigger asthma and other acute effects.
Ready to run the numbers?
Open Particulate Concentration Calculator