EARTH · RADIATION WATCH
Background Radiation, Measured Live
A live map of background radiation from two open networks: the US government’s EPA RadNet fixed gamma monitors and the global Safecast citizen-science sensor network. Every monitor is coloured by its dose rateagainst typical natural background — radar-green where the air reads normal, through to red where a reading is elevated. Tap a monitor for its latest figure, in both nSv/h and µSv/h, with the time it was taken. The numbers are real, sourced and dated — and framed as measurements, never as a safety verdict.
What the colours mean
Every monitor is tinted by its dose-equivalent rate— how much radiation dose you would receive per hour standing there. The scale is drawn relative to typical natural background (0.05–0.20 µSv/h (50–200 nSv/h)), the everyday range that comes from cosmic rays, the ground, and the air. It is a reading aid, nota regulatory threshold: many perfectly ordinary places — up a mountain, on granite bedrock — read a little higher, and that is normal.
If the units are unfamiliar, two short explainers unpack them — what a normal reading actually is, and how sieverts, millisieverts and microsieverts fit together:
The two networks on the map
The US Environmental Protection Agency runs a national network of fixed monitors that report a dose rate in nSv/h roughly every hour (brighter-ringed dots on the map). Built to catch any change during a radiological event.
Safecast is an open, volunteer-run network born after Fukushima. Its fixed Geiger sensors report a count rate (CPM), which we convert to a dose rate using the tube’s published factor. The reach is global, the data is CC0.
US monitors, city by city
Open any EPA RadNet station for its latest reading and recent hours — a live dose rate for that city.
Every US RadNet station
Anaheim, CA · Atlanta, GA · Bakersfield, CA · Baltimore, MD · Baton Rouge, LA · Birmingham, AL · Bloomsburg, PA · Boise, ID · Boston, MA · Carlsbad, NM · Casper, WY · Colorado Springs, CO · Columbus, OH · Concord, NH · Corvallis, OR · Denver, CO · Detroit, MI · Dover, DE · El Paso, TX · Eureka, CA · Fairbanks, AK · Fort Madison, IA · Fort Smith, AR · Fort Worth, TX · Fresno, CA · Grand Junction, CO · Grand Rapids, MI · Harlingen, TX · Hartford, CT · Honolulu, HI · Houston, TX · Idaho Falls, ID · Indianapolis, IN · Jacksonville, FL · Jefferson City, MO · Kalispell, MT · Kansas City, KS · Laredo, TX · Little Rock, AR · Los Angeles, CA · Louisville, KY · Lubbock, TX · Mason City, IA · Memphis, TN · Milwaukee, WI · Mobile, AL · Montgomery, AL · Navajo Lake, NM · New York City, NY · Omaha, NE · Orlando, FL · Orono, ME · Phoenix, AZ · Portsmouth, NH · Richland, WA · Riverside, CA · Saint Paul, MN · San Angelo, TX · San Bernardino, CA · San Diego, CA · San Francisco, CA · San Jose, CA · San Juan, PR · Shawano, WI · Shreveport, LA · Springfield, MO · Syracuse, NY · Tallahassee, FL · Tampa, FL · Tulsa, OK · Washington, DC · Wichita, KS · Wilmington, NC · Worcester, MA · Yaphank, NY · Yuma, AZ
See it in context
About this data
US government readings come from EPA RadNet (US federal data, public domain), which reports a native dose-equivalent rate in nanosieverts per hour and approves each station’s data on a short lag, so a station’s newest figure may be a few hours old. Global readings come from the Safecast realtime network (data dedicated to the public domain under CC0); its sensors report a Geiger count rate, which we convert to a dose rate using the published factor for each tube, and we show the raw count too. We plot only readings with a valid, recent timestamp and real coordinates, and we show each figure with the time it was taken. This is a measurement map, not medical or safety advice; if a reading matters to you, consult the source network directly.