About Smog Report

Smog Report is an independent iOS app that turns official, reference-grade air-quality data into a fast, no-friction way to see what you're breathing — across ~100 countries, with the right local index for wherever you are, for every location you save, and with Lock Screen alerts that arrive even when the app is closed. No account required, and your location is sent only to the relevant air-quality service — never to a server we operate.

Our mission

Air quality affects how you feel, how well you sleep, how hard you can train, and — for tens of millions of people with asthma, COPD, or cardiovascular conditions — whether the day is safe to spend outside. Government air-quality data already exists and is excellent, but for most people it's still hidden behind clunky map sites and acronyms. Our job is to surface that data on the device people already check first thing in the morning, in the simplest possible form: a number, a color, a recommendation.

How Smog Report works

When you open the app, it asks for your location (or you can search for any place), then queries the nearest reference-grade monitor — EPA AirNow in the US, OpenAQ across ~100 other countries, or a national agency like Singapore's NEA. It shows the current Air Quality Index on the index your country actually uses — the US EPA's 0-to-500 AQI, the UK's DAQI, Europe's EAQI, Canada's AQHI, Singapore's PSI, India's NAQI, Korea's CAI, or Australia's AQI — color-coded from green (Good) to the top of each scale, along with the pollutant driving that reading (usually fine particulate matter, PM2.5, or ozone, O₃) and the official health guidance for that level. You can also override the scale in Settings if you prefer a specific one. Where the data source supports it, forecasts are pulled the same way, so you can decide tonight whether tomorrow's run is safe.

The app is also home to widgets and Live Activities so the AQI sits on your home screen and lock screen. You don't need to open the app to know.

Where the data comes from

Every reading you see comes from official, reference-grade monitors — never consumer or citizen sensors — drawn from the right source for your location:

• United States: AirNow, the official U.S. air quality data service operated by the U.S. EPA in cooperation with NOAA, the National Park Service, and tribal, state, and local agencies. AirNow aggregates readings from thousands of regulatory-grade monitors and runs the EPA's NowCast algorithm to translate raw hourly measurements into the AQI you see.
• ~100 other countries: OpenAQ, a U.S. nonprofit that aggregates measurements from government and research-grade reference monitors worldwide.
• Singapore: the National Environment Agency's official PSI feed via data.gov.sg.

The app is not affiliated with the EPA, NOAA, OpenAQ, Singapore's NEA, or any government agency — we just consume their public APIs and present the result on the air-quality index your country uses. If you want to learn more about how the data flows from a sensor on a rooftop to the number you see, see our guide: How AirNow data works, or AQI around the world for how indices differ by country.

Editorial standards

The guides on this site are not original research. They are curated summaries of published guidance from public-health authorities — primarily the U.S. Environmental Protection Agency (EPA), the World Health Organization (WHO), the U.S. Centers for Disease Control and Prevention (CDC), and the California Air Resources Board (CARB). Each guide opens with a "Compiled from primary sources" panel that names and links to the specific publications it draws from, so any claim can be traced back to its source in one click.

Tables of EPA values (the AQI category scale, pollutant breakpoints, NAAQS standards) are reproduced as published, with an explicit source caption. The surrounding plain-English descriptions are Smog Report's own paraphrase of the published guidance, written to make the underlying material easier to read — not to add new claims.

Where a guide touches on health effects, action thresholds, or protective measures, it carries a "Not medical advice" disclaimer making clear that it summarizes published public-health guidance for general information and is not a substitute for a clinician. We do not publish original medical recommendations.

We do not accept payment for editorial coverage, we do not write sponsored guides, and the choice of topics is driven by what readers ask in our support inbox — not by advertising relationships. The site does run Google AdSense (disclosed in our Privacy Policy), but ad inventory and editorial content are separated: advertisers have no input into what we publish.

If you find a factual error or a source we should be citing more clearly, please email hello@smogreport.com — we'll correct the page and note the correction.

Privacy, in plain language

The iOS app does not require an account, and your location is sent only to the relevant air-quality service for your location — EPA AirNow in the US, OpenAQ elsewhere, or Singapore's NEA — never to a server we operate, and never to any advertising service. Starting with version 2.5.1, the app does show a small number of native ads via Google AdMob in two engaged-surface placements (the bottom of the main AQI scroll and the bottom of the About screen). Ads never appear on watchOS, in widgets, or in Live Activities. They're suppressed when you've tipped, during the first few launches, when AQI is unhealthy, when you're offline, when accessibility settings are on, and when a remote kill switch is set. You can also remove ads permanently with a tip from the in-app Tip Jar. The smogreport.com website is a separate surface and also runs Google Analytics and Google AdSense. Full details, including opt-out instructions, are in our Privacy Policy.

Contact

Feedback, bug reports, story tips, or just hello: hello@smogreport.com. For known issues and troubleshooting steps, start with the Support page.