---
title: "Safecast"
chunk: 1/1
source: "https://en.wikipedia.org/wiki/Safecast"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:15:46.598403+00:00"
instance: "kb-cron"
---

Safecast is an international volunteer-driven nonprofit organization focused on citizen science and environmental monitoring. Founded in 2011 in the aftermath of the Fukushima Daiichi nuclear disaster, it is best known for collecting and publishing open radiation data and for developing community-based environmental sensing projects.
Safecast publishes its measurements as open data under a CC0 public-domain dedication and makes them available through a public API and interactive map. Its data and methods have been discussed in both scientific and social-scientific literature as an example of post-disaster citizen sensing and open environmental data production.


== History ==
Safecast was initiated on 12 March 2011, one day after the 2011 Tōhoku earthquake and tsunami and the beginning of the Fukushima nuclear accident. It was founded by Sean Bonner, Joi Ito, and Pieter Franken in response to the lack of accessible, granular, and trusted public radiation information after the disaster.
Initially centered on post-Fukushima radiation monitoring in Japan, the project developed a volunteer-based model for gathering, uploading, and openly sharing geolocated environmental measurements. Over time it expanded into broader environmental sensing, including air-quality monitoring.


== Data and methodology ==
Safecast's principal activity has been the collection and publication of ionizing radiation measurements, especially ambient dose-rate data gathered by volunteers using mobile and fixed sensors. Measurements are uploaded to the organization's database and displayed through its public map.
The organization states that all collected data are released under a CC0 public-domain designation. Safecast data are also distributed through external open-data repositories, including the AWS Registry of Open Data.
A 2020 study in the Journal of Environmental Radioactivity reported that Safecast had accumulated more than 120 million observations by January 2020 and used those data to estimate mean ambient dose rates in 330 cities worldwide. Safecast's website later described its radiation archive as the largest open dataset of background radiation measurements collected to date.
Independent validation work has also compared Safecast data with official aerial survey data gathered by the United States Department of Energy and the National Nuclear Security Administration in Fukushima Prefecture, finding the datasets to be highly correlated.


== Devices ==
Safecast has developed and supported several open-hardware environmental sensing devices. Its best-known instrument is the bGeigie Nano, a GPS-enabled mobile radiation sensor used primarily for car-borne mapping, but also for static readings and contamination surveys. The device has been described in the scientific literature as one of the main tools used in the Safecast monitoring project.

In 2021 Safecast introduced the bGeigie Zen, an updated mobile radiation sensor based on the earlier bGeigie design.
Safecast has also developed air-quality sensing projects and devices to monitor particulate matter, including PM1.0, PM2.5 and PM10.


== Ukraine initiative ==
Following the Russian invasion of Ukraine in 2022 and Russian military activity in the Chernobyl Exclusion Zone, Safecast launched the bGeigies for Ukraine initiative in cooperation with SaveDnipro, the Czech National Radiation Protection Institute (SÚRO), and the Chornobyl Radiation and Ecological Biosphere Reserve.
According to Safecast, the project was intended to support rapid, open radiation monitoring after the withdrawal of Russian troops from contaminated areas. In September 2022, the organization stated that the initiative had gathered more than 300,000 radiation data points in Ukraine.


== See also ==
Citizen science
Fukushima Daiichi nuclear disaster
Environmental monitoring
Open data


== References ==


== External links ==

Official website
Safecast Map