Air Pollution Index Calculator

Enter Pollutant Data

Site Name

Optional label for report exports.

Sample Date

Optional monitoring date.

PM2.5

Fine particulate matter in µg/m³.

PM10

Coarse particulate matter in µg/m³.

O₃ (8-hour)

Ozone concentration in ppm.

CO

Carbon monoxide in ppm.

SO₂

Sulfur dioxide in ppb.

NO₂

Nitrogen dioxide in ppb.

Example Data Table

Scenario	PM2.5	PM10	O₃	CO	SO₂	NO₂	Overall AQI	Category
Urban weekday sample	18.0	72	0.061	2.1	14	34	71	Moderate
Busy traffic corridor	42.3	168	0.074	5.6	48	82	118	Unhealthy for Sensitive Groups
Heavy emission event	88.0	286	0.092	13.4	210	410	168	Unhealthy

Formula Used

The calculator applies the standard pollutant sub-index interpolation method. Each measured concentration is matched with its breakpoint interval, then converted into a sub-index.

Sub-index formula:
I = ((I_high - I_low) / (C_high - C_low)) × (C - C_low) + I_low

I = calculated sub-index for one pollutant.
C = observed pollutant concentration.
C_low and C_high = concentration breakpoints surrounding the observed value.
I_low and I_high = AQI breakpoint values attached to that range.
Overall AQI = maximum sub-index among all entered pollutants.
Dominant pollutant = pollutant producing the highest sub-index.

This method preserves pollutant-specific health significance while keeping the final index easy to interpret for engineering reviews, environmental dashboards, and reporting.

How to Use This Calculator

Enter an optional site name and sample date for reporting.
Fill in one or more pollutant concentrations using the listed units.
Click Calculate Air Pollution Index to compute pollutant sub-indices.
Review the overall AQI, category, dominant pollutant, and health guidance shown above the form.
Inspect the Plotly graph to compare pollutant influence visually.
Download the result summary as CSV or PDF for records.

For better comparability, enter concentrations from the correct averaging periods, especially for ozone and other time-sensitive pollutants.

Frequently Asked Questions

1. What does the calculator actually measure?

It converts pollutant concentrations into pollutant sub-indices, then reports the highest one as the overall air pollution index or AQI.

2. Why is the highest sub-index used?

The highest sub-index represents the pollutant creating the greatest health concern at that time, so it becomes the overall air quality indicator.

3. Can I leave some pollutant fields empty?

Yes. The calculator works with any combination of entered pollutants, though fuller input gives a more useful environmental snapshot.

4. What units should I enter?

Use the exact units shown beside each field: particulate matter in µg/m³, ozone and carbon monoxide in ppm, and sulfur dioxide and nitrogen dioxide in ppb.

5. Does the graph show concentrations or index values?

The graph displays calculated pollutant sub-indices, making it easier to see which pollutant most strongly drives the overall air quality category.

6. What happens if a concentration is extremely high?

Values exceeding the highest supported breakpoint are capped at an AQI of 500, which represents the upper hazard limit in this tool.

7. Can I use this for compliance reporting?

It is useful for screening, dashboards, and internal engineering review, but formal compliance submissions should still follow local regulatory methods.

8. Why does ozone specify 8-hour averaging?

AQI breakpoints depend on averaging time. Entering the correct averaging basis helps keep the reported ozone sub-index technically meaningful.