Methodology, data sources, and update policy
This site is designed to help people interpret AQI and make air-quality decisions. The estimate is intentionally simple enough to be understandable, while still tied to recognizable public methodology.
1. AQI to PM2.5
The calculator first converts AQI into an estimated PM2.5 concentration using EPA-style AQI breakpoint logic. AQI is easier to look up, while PM2.5 is the dose unit needed for the cigarette-equivalent framing.
Primary reference: AirNow AQI calculator and AQI breakpoint methodology.
2. PM2.5 to cigarette-equivalent exposure
After estimating PM2.5, the site uses the Berkeley Earth cigarette-equivalence framing to make the exposure easier to understand. In plain terms, it estimates how much PM2.5 exposure corresponds to the particulate dose from cigarettes over time.
Primary reference: Berkeley Earth's air pollution and cigarette equivalence framing.
3. What the estimate is good for
4. Important limitations
- The estimate is not a medical diagnosis and does not predict an individual health outcome.
- AQI varies by pollutant and local conditions. This tool is most aligned with PM2.5-oriented exposure interpretation.
- Real-world exposure changes with exertion, indoor leakage, masks, ventilation, and time spent in cleaner or dirtier microenvironments.
5. Update policy
We review the site when the calculator logic changes, when key methodology references materially change, or when new internal content is added. Supporting pages are updated to improve clarity, internal linking, and user decision value.
The city and scenario pages are intentionally framed as planning aids, not live-data feeds. Users should pair them with a current AQI source and then use this site to interpret what that number means.