OSHA NIOSH Heat Safety Tool

Name: OSHA NIOSH Heat Safety Tool
Author: US Centers for Disease Control and Prevention

US Centers for Disease Control and Prevention

VALIDATED

Studied in research · Did not demonstrate expected effectiveness

For:General Public & EnthusiastsIndustry Professionals

Free

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App Summary

The OSHA NIOSH Heat Safety Tool is a reference app designed for outdoor workers that provides location-specific heat index values and corresponding safety recommendations to help prevent heat-related illness. An evaluation study (N=682 measurements) comparing the app's heat index to gold-standard wet bulb globe temperature (WBGT) found it was reliable for minimal-to-moderate risk conditions but failed to identify any high or extreme risk conditions. The associated research concludes that the app is not sufficiently protective for workers under heavy workloads and that direct environmental monitoring should be used for accurate risk assessment in these settings.

App Screenshots

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Detailed Description

Functionality & Mechanism

Developed by the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH), this tool leverages device location data to calculate a real-time heat index and project hourly forecasts. The interface displays a visual risk level indicator alongside corresponding occupational safety recommendations. The system also contains reference modules detailing symptoms and first aid protocols for heat-related illnesses. Users can manually modulate location, temperature, and humidity inputs for variable condition analysis.

Evidence & Research Context

A comparison study evaluated the app's heat index-based risk assessments against the gold-standard Wet Bulb Globe Temperature (WBGT) monitor in an agricultural setting (N=682 measurements).
The app demonstrated high agreement with WBGT for lower-risk scenarios, correctly identifying 94% of moderate risk conditions for light workloads and 74% of low risk conditions for moderate workloads.
Reliability diminished significantly under more strenuous conditions; the app failed to identify any instances of high or extreme risk, regardless of workload type.
The study's authors concluded the app's risk assessment is not sufficiently protective for workers engaged in heavy workloads and did not recommend its use for formal risk assessment in agricultural settings.

Intended Use & Scope

This tool is intended for outdoor workers and supervisors as a resource for general awareness and preliminary activity planning. It is not a substitute for direct environmental monitoring via a Wet Bulb Globe Temperature (WBGT) instrument. The app's risk assessment may be insufficient for high-exertion work, and users must adhere to established occupational safety protocols.

Studies & Publications

1 publication

Peer-reviewed research associated with this app.

Validation Study

Comparison between OSHA-NIOSH Heat Safety Tool app and WBGT monitor to assess heat stress risk in agriculture

Dillane et al. (2020) · Journal of Occupational and Environmental Hygiene

App measurements did not reliably match the reference standard, missing all high-risk heat stress conditions.

Agricultural workers are exposed to heat stress due to spending significant amount of time outdoors. Risk information from mobile apps is more readily available for timely advice on risk management that is crucial in preventing severe acute illnesses and deaths, but its reliability is unknown. The purpose of this study was to determine the reliability of the OSHA-NIOSH Heat Safety Tool mobile app in providing accurate risk information to prevent heat-related illnesses among agricultural workers in eastern North Carolina. Wet bulb globe temperature (WBGT) indices were datalogged at two agricultural sites using heat stress monitors from April–August 2019 and were assigned to risk levels (minimal, low, moderate, high, extreme) by workload (light, moderate, heavy, very heavy) based on the ACGIH® Threshold Limit Values (TLVs®). Hourly heat index (HI) and its corresponding risk level were obtained using the app. Hourly HI-based risk level assignments were time-matched to their corresponding WBGT-based risk level assignments (682 pairs) and analyzed using cross-tabulation by determining the percentage of hourly WBGT-based risk level assignments ("gold standard") with the same hourly HI-based risk level assignments under different workloads, with a higher percentage indicating higher app reliability. Results showed that the app correctly identified 60–100% of minimal risk conditions, depending on workload type, but its reliability decreased as the heat stress risk condition and workload became more severe. The app identified the majority of low risk conditions for a moderate workload (74%) and moderate risk conditions for a light workload (94%) only, indicating limited use in these specific conditions, while the app identified 0% of either the high risk or extreme risk conditions at any workload type. It is concluded that the performance of the OSHA-NIOSH app in assessing occupational risk to heat stress is not protective of workers particularly for heavy and very heavy workloads, and that the use of the app for the assessment of occupational heat stress risk in agricultural settings is not recommended.

In the Media

Beat the heat with the OSHA-NIOSH mobile app

The Centers for Disease Control and Prevention's National Institute for Occupational Safety and Health (NIOSH) redesigned OSHA's original Heat Safety Tool as a free mobile app to help individuals stay safe in hot weather, using GPS to extract temperature and humidity data from National Oceanic and Atmospheric Administration satellites. According to OSHA, "extreme heat causes more deaths than any other weather-related hazard," making this tool particularly valuable as climate change drives rising temperatures. The app provides color-coded risk levels and specific safety recommendations based on calculated heat index values.

BmjRead article

Announcing OSHA-NIOSH Heat Safety Tool

OSHA and NIOSH collaborated to update and rebrand the OSHA Heat Safety Tool, creating the OSHA-NIOSH Heat Safety Tool with a refreshed interface for both Android and iPhone users. Since the original app's launch in 2011, more than 450,000 users have downloaded the OSHA Heat Safety Tool, and both agencies expect the co-branded version to reach even more users. The original OSHA Heat Safety Tool was discontinued for download after September 30, 2017.

AohpRead article

Redesigned Heat Safety Tool app released (updated)

The National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) collaborated to update OSHA's original Heat Safety Tool app, providing a clearer user interface while maintaining essential information to protect outdoor workers in hot weather. The app addresses a critical need, as extreme heat causes more deaths than any other weather-related hazard and more than 65,000 people seek medical treatment for extreme heat exposure annually. The updated tool forecasts hourly heat index throughout entire workdays and provides tips for recognizing heat-related illness signs.

NalcRead article

NIOSH, OSHA update heat safety app for outdoor workers

NIOSH and OSHA teamed up to update a heat safety mobile app that uses temperature and humidity to measure heat index values for outdoor workers exposed to heat on the job. "With the hot summer months on our doorstep, this app is a valuable tool for employers and workers to help prevent heat-related illnesses," NIOSH Director John Howard said. The free app uses geolocation technology to assess current heat index and risk levels while offering projected heat indices throughout the workday.

SafetyandhealthmagazineRead article

NIOSH and OSHA Introduce Improved Heat Safety App for Outdoor Workers

NIOSH and OSHA redesigned the OSHA-NIOSH Heat Safety Tool to help outdoor workers prevent heat-related illnesses by calculating heat index values based on temperature and humidity data from NOAA satellites. "With the hot summer months on our doorstep, this app is a valuable tool for employers and workers to help prevent heat-related illnesses," said NIOSH director John Howard, M.D. The updated app uses geolocation capabilities to show current risk levels and hourly heat index forecasts throughout the workday.

PR NewswireRead article

OSHA, NIOSH Release Redesigned Heat Safety Tool App

NIOSH and OSHA released a redesigned, co-branded Heat Safety Tool app to help users plan outdoor work activities based on real-time heat conditions, replacing OSHA's original 2011 version with updated guidance and location-specific forecasts. "Since workers in hot environments experience heat stress from a combination of environmental factors and metabolic heat from the tasks they are performing, OSHA modified some of the heat index cutoffs to create heat index-associated protective measures for worksites," explains NIOSH health scientist Brenda Jacklitsch.

AihaRead article

Heat Index: When humidity makes it feel hotter

NIOSH and OSHA recently released a redesigned, co-branded Heat Safety Tool App that calculates the heat index at outdoor worksites using smartphone geolocation capabilities to pull current weather conditions from NOAA satellites. The app provides specific protection recommendations based on calculated heat index values, with updates reflecting information from the NIOSH Criteria for a Recommended Standard published in 2016. This version replaces the original app created by OSHA in 2011 and features improved usability for workers and managers adjusting outdoor work environments.

CdcRead article

OSHA Launches New Version of its Heat Safety Tool App to Keep Workers Safe in Summer Weather

The Occupational Safety and Health Administration (OSHA) released a new version of its Heat Safety Tool mobile app in 2015 to help outdoor workers prevent heat illness, partnering with the Presidential Innovation Fellows program to modernize the platform. With nearly 200,000 downloads since its 2011 launch, the app has been one of the most successful mobile apps developed by the Federal government. The updated version features a user-centric design, Section 508 compliance for accessibility, Spanish language support, and open-source code availability.

ArchivesRead article