OSHA Heat Index Calculator

OSHA Heat Index Equation:

\[ HI = -42.379 + 2.04901523 \times T + 10.14333127 \times RH - 0.22475541 \times T \times RH - 0.00683783 \times T^2 - 0.05481717 \times RH^2 + 0.00122874 \times T^2 \times RH + 0.00085282 \times T \times RH^2 - 0.00000199 \times T^2 \times RH^2 \]

Heat Index (HI):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the OSHA Heat Index?

The OSHA Heat Index is a measure of how hot it feels when relative humidity is factored with the actual air temperature. It provides important information for assessing heat stress risk in workplaces.

2. How Does the Calculator Work?

The calculator uses the NWS Heat Index equation:

Where:

\( T \) — Temperature in degrees Fahrenheit
\( RH \) — Relative humidity percentage

Explanation: The equation accounts for the combined effects of temperature and humidity on human perception of heat.

3. Importance of Heat Index Calculation

Details: The heat index is crucial for workplace safety, helping to prevent heat-related illnesses by determining when extra precautions are needed.

4. Using the Calculator

Tips: Enter temperature in °F and relative humidity in %. Both values must be valid (temperature > 0°F, humidity between 0-100%).

5. Frequently Asked Questions (FAQ)

Q1: What heat index level requires precautions?
A: OSHA recommends precautions starting at 91°F, with increasing protections as the heat index rises.

Q2: How does heat index affect the body?
A: High heat index makes it harder for the body to cool itself through sweating, increasing risk of heat exhaustion or heat stroke.

Q3: When is heat index most important?
A: Particularly important during hot weather, especially for outdoor workers or those in hot indoor environments.

Q4: Are there limitations to this calculation?
A: The index assumes shade and light wind conditions. Full sun exposure can increase felt temperatures by up to 15°F.

Q5: What actions should be taken at different heat index levels?
A: OSHA provides specific recommendations for worker protections at different heat index ranges (caution, extreme caution, danger, extreme danger).