Tecnobosque Wildfire Knowledge Graph · Smoke & Indoor Air
Reference Concept · v1.0Definition → relationship → calculation → evidence context
The Air Quality Index (AQI) is a dimensionless public-health communication scale that converts pollutant concentrations, including PM2.5, into standard index categories using defined breakpoints.
AQI
What is air quality index (aqi)?
EPA AQI maps pollutant concentrations to common health-communication categories. For particle pollution, the PM2.5 concentration is first matched to the appropriate breakpoint interval and then linearly interpolated to the corresponding AQI interval.
Breakpoint tables can change when standards and AQI policy are updated. A calculator should therefore state which breakpoint set it uses rather than treating the mapping as timeless.
Why it matters
During wildfire smoke events, PM2.5 often drives the AQI. Correct conversion matters because current PM2.5 breakpoints determine the category shown to the public.
AQI is not a particle concentration. It translates a concentration into a common 0–500 scale so air-quality conditions can be communicated consistently.
I = ((I_hi − I_lo)/(C_hi − C_lo)) × (C − C_lo) + I_loAQI is calculated piecewise inside the pollutant breakpoint interval containing concentration C. Use the current EPA breakpoint table and required concentration truncation/rounding rules.
Interpolated air-quality index.
Concentration being converted.
Bounds of the applicable pollutant interval.
AQI bounds paired with the concentration interval.
Piecewise AQI conversion
Suppose a PM2.5 concentration falls inside the EPA interval paired with AQI 101–150.
Identify the correct concentration interval.Insert C and both breakpoint pairs into the interpolation equation.Apply the EPA-specified concentration handling and round the final AQI to an integer.Always use the current EPA table; do not reuse an old breakpoint set without labelling it.
What controls or changes this quantity?
AQI changes as measured concentration moves through the breakpoint intervals.
Updated standards or AQI policies can change concentration-to-index mapping.
Ozone, particles and other criteria pollutants use different breakpoint tables.
AQI calculations follow pollutant-specific concentration handling and reporting conventions.
Engineering context
AQI 0–50
AQI 51–100
AQI 101–150
AQI 151+ spans progressively more severe categories.
How to interpret it correctly
- State that the index is US EPA AQI if using EPA breakpoints.
- Keep the original PM2.5 concentration available alongside AQI.
- Use current breakpoint tables and label the version/date.
- Do not convert an indoor PM2.5 value to AQI and then imply it is an official ambient AQI report.
Use the calculator as a transparent technical aid and keep its assumptions explicit.Open PM2.5 ↔ AQI Calculator →
Why it matters in wildfire analysis
During wildfire smoke, AQI is excellent for communication while PM2.5 concentration is usually the more direct engineering variable for filtration and indoor mass-balance calculations.
Tecnobosque therefore links AQI to PM2.5 rather than replacing the underlying concentration.
Limitations and boundaries
- AQI compresses pollutant concentration into a communication index and loses some quantitative detail.
- Official AQI reporting may use monitoring and averaging procedures not reproduced by a simple web conversion.
- Indoor PM2.5 converted to AQI is an interpretive comparison, not an official ambient AQI measurement.
Air Quality Index (AQI) FAQ
What does AQI mean?
Air Quality Index is a public-health communication scale that converts pollutant concentrations to a common index.
Is AQI measured directly?
Usually no. It is calculated from pollutant concentration using defined breakpoint intervals.
What pollutant usually drives wildfire-smoke AQI?
PM2.5 commonly drives AQI during wildfire smoke events.
Can PM2.5 and AQI have the same number?
They can coincide numerically by chance, but they are different quantities and units.