Air Quality Index Calculator
About the Air Quality Index Calculator
The Air Quality Index Calculator is a scientifically accurate, real-time online tool that instantly computes the official Air Quality Index (AQI) using the latest United States EPA formula (updated 2024), India NAAQS, and provides comparisons with WHO Air Quality Guidelines. It supports all eight major pollutants (PM₂.₅, PM₁₀, O₃, CO, SO₂, NO₂, NH₃, Pb) with correct breakpoints, averaging times, and health risk categorization. Built on peer-reviewed methodology from the U.S. Environmental Protection Agency Technical Assistance Document (2018, 2024 revision) and WHO Global Air Quality Guidelines (2021), this calculator delivers trustworthy results used by governments, researchers, farmers, schools, and citizens worldwide.
More details at Air Quality Index on Wikipedia.
Importance of the Air Quality Index Calculator
Every year, air pollution causes over 7 million premature deaths globally (WHO). AQI translates complex pollutant concentrations into a single, easy-to-understand number and color code that tells people when it is safe to exercise outdoors, when children should stay inside, and when emergency measures are needed. In agriculture, high AQI days reduce crop photosynthesis, increase livestock stress, and endanger farm workers — issues actively addressed by platforms like Agri Care Hub.
This free calculator removes confusion between different national standards, instantly shows the dominant pollutant (“NowCast” method for PM and O₃), and provides actionable health advice in seconds — saving lives and improving quality of life.
Purpose of the Air Quality Index Calculator
Main functions:
- Calculate official US EPA AQI (0–500+)
- Support India NAAQS AQI (PM₂.₅, PM₁₀, O₃, CO, SO₂, NO₂, NH₃, Pb)
- Apply correct averaging periods and NowCast for real-time accuracy
- Show dominant pollutant and health risk category (Good to Hazardous)
- Compare with WHO 2021 guideline exceedance
- Instant health advisory for general public and sensitive groups
When and Why You Should Use It
Use this calculator whenever you have real-time or manual measurements from air quality monitors, purpleAir sensors, government stations, or low-cost sensors. Perfect for:
- Farmers checking if it’s safe to burn stubble or operate diesel equipment
- Parents deciding if children can play outside
- Schools planning outdoor activities
- Doctors advising patients with asthma/COPD
Scientific Details & Health Breakpoints
The AQI is calculated using the EPA linear segmented formula:
I = [(I_high − I_low) / (BP_high − BP_low)] × (C − BP_low) + I_low
where C = pollutant concentration, BP = breakpoint, I = index.
Current WHO 2021 24-h guidelines (µg/m³): PM₂.₅: 15 | PM₁₀: 45 | O₃: 100 | NO₂: 25 | SO₂: 40
Full EPA breakpoints and color scale are embedded in the calculator with microgram/cubic-meter and ppm/ppb conversions at 25 °C, 1013 hPa.
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