Enter your room dimensions, ventilation rate, and pollutant sources to estimate your Indoor Air Quality (IAQ). The calculator returns a pollutant concentration in µg/m³, an air quality index score, and a health risk rating — helping you understand whether your indoor environment meets safe exposure thresholds set by the EPA.
Estimated Indoor PM2.5 Concentration
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Estimated AQI Score
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Health Risk Rating
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Source Emission Rate
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Purifier Reduction
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It estimates the concentration of airborne pollutants — particularly PM2.5 fine particulate matter — inside a room based on its size, ventilation rate, outdoor air quality, and indoor emission sources. The result is expressed in µg/m³ and mapped to an Air Quality Index (AQI) score so you can compare against EPA health thresholds.
The EPA's 24-hour PM2.5 standard is 35 µg/m³, while the annual standard is 12 µg/m³. For ongoing indoor exposure, levels below 12 µg/m³ are considered good. Concentrations between 35–55 µg/m³ are unhealthy for sensitive groups, and anything above 55 µg/m³ poses risks for the general population.
Ventilation dilutes indoor pollutants by replacing contaminated air with outdoor air. A higher Air Changes per Hour (ACH) rate flushes out pollutants faster, lowering steady-state concentrations. However, in areas with high outdoor pollution, increasing ventilation can also bring in more outdoor contaminants — so purifiers may be needed.
ACH measures how many times the total air volume in a room is replaced in one hour. A typical home has 0.35–1 ACH through natural infiltration. Mechanical ventilation systems in offices and commercial buildings typically deliver 4–10 ACH. Higher ACH values generally mean better dilution of indoor pollutants.
A HEPA air purifier removes at least 99.97% of particles ≥0.3 µm in the air it processes. Its effectiveness in a room depends on its Clean Air Delivery Rate (CADR) relative to the room volume. A high-capacity unit (CADR ~350 m³/h) in a medium room can reduce PM2.5 concentrations by 50–70% when running continuously.
Gas cooking — especially frying or grilling — is one of the largest sources of indoor PM2.5, often spiking levels above 100 µg/m³ during cooking. Wood-burning fireplaces, cigarette smoking, burning candles or incense, and VOC-emitting cleaning sprays are also major contributors. Even laser printers release ultrafine particles during operation.
PM2.5 is a direct physical measurement of fine particulate matter concentration in micrograms per cubic metre (µg/m³). The AQI (Air Quality Index) is a standardised 0–500 scale that converts pollutant concentrations into a colour-coded category (Good, Moderate, Unhealthy, etc.) for easier public communication. This calculator converts PM2.5 to an estimated AQI using EPA breakpoints.
Currently, the calculator models one primary source at a time combined with the outdoor background level. For spaces with multiple simultaneous sources — such as cooking while a fireplace is active — run separate estimates for each and consider the results additive. Selecting a higher-emission source and a longer activity duration provides a conservative worst-case estimate.