The OSHA-NIOSH Heat Safety Tool represents a specialized mobile application developed by federal health and safety agencies to address occupational heat exposure risks. This free iOS application serves as a digital companion for outdoor workers and safety professionals, delivering authoritative heat safety guidance directly from the Centers for Disease Control and Prevention's research divisions. The application's core functionality centers on real-time heat index calculations based on user location, combining temperature and humidity data to generate risk assessments. It provides color-coded risk levels ranging from lower to extreme danger, accompanied by specific OSHA-recommended protective measures. The hourly forecast feature allows for shift planning, while educational sections detail heat illness symptoms, first aid procedures, and employer compliance requirements. All content is available in both English and Spanish, addressing language diversity in outdoor workforces. User experience demonstrates a utilitarian interface prioritizing clarity over aesthetic appeal. The home screen displays current conditions through a prominent visual indicator, with navigation tabs accessing detailed recommendations. Real-world usage patterns show workers checking the app multiple times daily, particularly before and during outdoor shifts. The interface's simplicity enables quick risk assessment even in field conditions, though some users report occasional performance issues affecting reliability. User feedback reveals significant reliability concerns despite recent updates addressing stability problems. Multiple reviews from May 2024 (Mom in SWFL, 2024-05-25; treetopper75, 2024-05-25) documented application crashes that rendered the tool unusable, though subsequent updates appear to have resolved these issues according to July 2024 feedback (GrannysMoistToe, 2024-07-19). Positive reviews highlight the app's precision and practical value for outdoor workers like turtle brooks (2024-08-01), who relies on its hourly breakdowns and symptom identification features during summer work. The application's primary strength lies in its authoritative, research-backed content from federal safety agencies, making it uniquely trustworthy for compliance purposes. However, its 2.45 rating reflects persistent technical reliability issues that undermine its utility as a dependable safety tool. The app serves best as a supplemental planning resource rather than a primary safety monitoring system, particularly valuable for safety managers coordinating outdoor work schedules and needing official heat illness prevention guidelines.