Tap, assess, and cool.

1. Before work: NIOSH sample outdoor schedule

Choose a range for outdoor air temperature, sunlight, humidity and workload. The app selects the more protective work/rest entry from the chosen temperature band. Adjusted temperature = measured outdoor °F + sunlight (+13 full, +7 partial, +0 shade) + humidity (+0 below 40%, +3 at 40–49%, +6 at 50–59%, +9 at 60% or more). If humidity is unknown the app uses +9°F for screening. This is a NIOSH sample schedule per hour for its stated assumptions, not a universal safe threshold. “Normal” does not mean no heat hazard; “Caution” is not permission to continue work.

2. California rules are not the same as the sample schedule

When applicable, California outdoor standard 8 CCR §3395 requires water, access to shade (shade must be present above 80°F), preventive cool-down rest and other protections; high-heat procedures apply at 95°F or above. Indoor standard 8 CCR §3396 generally addresses work areas at 82°F or above, with further provisions at 87°F or in certain radiant-heat/clothing situations, plus exceptions. Determine applicability with the actual workplace and employer heat illness prevention plan. California does not require this app's example 60/90/120-minute recovery schedule.

3. WBGT: measurement and approximation

If a workplace WBGT meter reading is entered, the app screens it against simplified workload/acclimatization values; the difference is shown in °C WBGT, not minutes of rest owed. If humidity and enclosed-area temperature are given, the app may show an experimental shaded approximation using the Stull wet-bulb relationship and globe temperature assumed equal to air temperature. This is not a measured WBGT, does not reflect high radiant heating or PPE, and is never used for exceedance or recovery-time decisions. A measured WBGT cannot be directly substituted into the NIOSH adjusted-air-temperature schedule.

4. After work: exposure and optional cooling example

Outdoors, a vehicle/enclosed work area, and an indoor area confirmed below 80°F are logged separately. Time in a cooler environment may reduce heat exposure but is not automatically a duty-free break. The approximate time buttons are 0–19, 20–39, 40–60, and 60+ minutes; hot time uses the low end, cooler time uses the high end when one exists. The 60+ range has no known upper bound. If the outdoor or hot enclosed-area selection exceeds the sample outdoor work interval, the app displays a warning. This is a screening prompt: location totals do not establish the chronology of work and actual rest. The outdoor NIOSH table is not a validated cabin or indoor work/rest limit.

Illustrative nonregulatory recovery example: A user-reported cooling delay of 1–29 minutes maps to 60 minutes cooling, 30–59 minutes maps to 90 minutes, and 60+ maps to 120 minutes. If a duty-free cooled break is reported, the app subtracts only the lower end of the selected rest band. These example values are not NIOSH or California requirements, are not validated as individualized recovery times, and must not determine fitness to resume work. Symptoms or concern for heat illness always supersede a timer and trigger STAND DOWN guidance.