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Your alerts
Alerts update only while this page is open — there is no background push or account.
Neighborhood alerts
Areas where heat or air quality has crossed a public-health danger threshold this hour. Aggregate environmental data — no account, no tracking.
Subscribe by adding the alert feed to any RSS/Atom reader, or point an automation at it. The feed is public and carries no personal data; thresholds follow US-EPA and US-NWS bands.
Right now across the network
Which sensors need attention
| Air quality | Status |
|---|
An interactive map of sensor locations — drag to pan, scroll or pinch to zoom, or use the buttons and arrow keys. Each marker states its reading in text; the same data is in the List and Table tabs for any reader the map does not serve.
Cooling centers
Public places to cool down — libraries, community and senior centers, and cooled public buildings. The list below is the accessible equivalent of the map overlay; everything shown on the map is here in text.
Selected location
Recent days here
Health context: US EPA AirNow.
What to do now
Practical steps drawn from US EPA and NWS guidance — not medical advice.
Show your work
Alert me about this location
Set a level for this measurement. While this page is open, you'll see an alert here when this location reaches it. Saved on this device only — no account, no server.
Air-quality categories (PM2.5)
What is AQI?
The Air Quality Index (AQI) turns a pollution concentration into a 0–500 scale and a named category. Higher is worse: 0–50 is Good, 100+ starts to affect sensitive people.
- Good — AQI 0 to 50
- Moderate — AQI 51 to 100
- Unhealthy for sensitive groups — AQI 101 to 150
- Unhealthy — AQI 151 to 200
- Very unhealthy — AQI 201 to 300
- Hazardous — AQI 301+
The AQI shown is computed from each location's hourly mean, not a 24-hour average.
- Coolest — below about 24 °C (75 °F)
- Cool — about 24 to 28 °C (75 to 82 °F)
- Warm — about 28 to 32 °C (82 to 90 °F)
- Hot — about 32 to 36 °C (90 to 97 °F)
- Hottest — about 36 °C (97 °F) and up
The shading is a coolest-to-hottest cue only — the number on each marker is the exact reading, in your chosen units.
- Minimal — little added heat or air stress
- Low — mild conditions
- Elevated — take some care outdoors
- High — limit time and exertion outdoors
- Extreme — avoid being outdoors
Heat + air exposure combines the heat index and the PM2.5 AQI into one level (Minimal to Extreme), taking the higher of the two and flagging when heat and air are both elevated. It is decision-support, not a validated health index, and never a claim that conditions are safe.
This measurement is shown by its value on each marker, not by a severity category. Higher numbers mean more of the pollutant; see the List or Table view for every location.
Provisional locations have only early, uncalibrated readings — still being double-checked, and never shown as a confirmed category. Status is conveyed by text and pattern, not color alone.
How to read this — and what it does not say
Confirmed readings are calibrated against a reference monitor and carry a ± uncertainty. Provisional readings are early and uncalibrated. This page reports what the air and heat readings are; it does not tell anyone they are safe. Use it alongside how you feel and official advisories.
How the numbers are made
- Confirmed means calibrated against a reference monitor; a sensor with no fit stays raw and is shown provisional.
- Every confirmed reading carries a ± 1-sigma uncertainty, published alongside it.
- Published locations snap to a ~150 m grid, so the map shows the area, not the porch.
- The AQI shown comes from each location's hourly mean, not the official 24-hour average.
- Heat + air exposure takes the higher of the heat and air levels — it never blends them into one number.
- All readings are public-domain (CC0) and downloadable — no account, no key.