Heat Stress Resource Page
Heat Index Chart
The Heat Index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature. To find the Heat Index temperature, look at the Heat Index Chart above or check our Heat Index Calculator. As an example, if the air temperature is 96°F and the relative humidity is 65%, the heat index--how hot it feels--is 121°F. The red area without numbers indicates extreme danger. The National Weather Service will initiate alert procedures when the Heat Index is expected to exceed 105°-110°F (depending on local climate) for at least 2 consecutive days.
Why humidity matters: Relative humidity is a measure of the amount of moisture in the air. Sweat does not evaporate as quickly when the air is moist as it does in a dry climate. Since evaporation of sweat from the skin is one of the ways the human body cools itself on a hot day, high humidity reduces our natural cooling potential and we feel hotter. Low humidity can also be a problem for outdoor workers in hot, desert-like climates. Sweat evaporates very rapidly in low humidity, which can lead to severe dehydration if a person does not drink enough water throughout the day.
IMPORTANT NOTE: The heat index values were devised for shady, light wind conditions, and exposure to full sunshine can increase heat index values by up to 15° Fahrenheit. To account for solar load, added precautions are recommended. See Protective Measures to Take at Each Risk Level.
NWS offers a slightly different Heat Index chart for area with high heat but low relative humidity.
Download OSHA's Heat Index Chart here...
Source:OSHA: Using the Heat Index: A Guide for Employers and National Weather Service
How to Recognize the Symptoms of Heat Stress
Heat stroke, the most serious form of heat-related illness, happens when the body becomes unable to regulate its core temperature. Sweating stops and the body can no longer rid itself of excess heat. Signs include confusion, loss of consciousness, and seizures. Heat stroke is a medical emergency that may result in death! Call 911 immediately.
Heat exhaustion is the body's response to loss of water and salt from heavy sweating. Signs include headache, nausea, dizziness, weakness, irritability, thirst, and heavy sweating.
Heat cramps are caused by the loss of body salts and fluid during sweating. Low salt levels in muscles cause painful cramps. Tired muscles—those used for performing the work—are usually the ones most affected by cramps. Cramps may occur during or after working hours.
Heat rash, also known as prickly heat, is skin irritation caused by sweat that does not evaporate from the skin. Heat rash is the most common problem in hot work environments.
Source: OSHA
Infographics
Infographic: Heat-Related Illnesses
Source: CDC
Infographic: Protect Your Workers from Heat Stress
Source: CDC and NIOSH
Infographic: Dehydration Indicator Chart
Source: Ergodyne
Infographic: Hydration Solutions
Source: Sqwincher
OSHA/NIOSH Infosheet and NIOSH Fast Facts
OSHA / NIOSH: Protecting Workers from Heat Illness
Source: OSHA and NIOSH
NIOSH Fast Facts: Heat Stress
Source: NIOSH
NIOSH Fast Facts: Sun Exposure
Source: NIOSH
NIOSH Fast Facts: Stinging Insects
Source: NIOSH
NIOSH Fast Facts: Ticks and Mosquitoes
Source: NIOSH
Printable Posters
Heat Illness Posters
Source: OSHA (Three posters in download)
Heat Related Illness Poster
Source: NIOSH
Ergodyne Toolbox Talks
Toolbox Talk: Heat Stress: Water, Rest and Shade
Source: Ergodyne
Toolbox Talk: Heat Stress: Water, Rest and Shade: Shade
Source: Ergodyne
Toolbox Talk: Heat Stress: Water, Rest and Shade: Water Wisdom
Source: Ergodyne
Toolbox Talk: Heat Stress: Water, Rest and Shade: Rest
Source: Ergodyne
OSHA Fact Sheets and Quick Card
OSHA Fact Sheet: Protecting Workers from the Effects of Heat
Source: OSHA
OSHA Fact Sheet: Working Outdoors in Warm Climates
Source: OSHA
OSHA Quick Card: Protecting Workers from Heat Stress
Source: OSHA
Heat Stress Guides
Guide to Heat Stress
Source: Ergodyne
Hot Weather Survival Guide
Source: SafetyNetwork.me and Safeopedia.com
Using the Heat Index: A Guide for Employers
Source: OSHA
Heat Training Guide
Source: OSHA
Q&A: How Can You Encourage Employee Hydration?
Source: Sqwincher
Heat Stress White Papers
Drink to Your Health
Source: Ergodyne
Beyond Water, Rest and Shade
Source: Ergodyne
Hydration: The Underappreciated Safety and Productivity Measure many Industrial Workplaces Miss
Source: Sqwincher and Safeopedia.com
Dangers of On The Job Dehydration
Source: Sqwincher
Products to Keep Workers Safe in Hot Weather
Hydration Products
Shade Products
Hi-Vis Safety Vests
Hi-Vis Safety Shirts
Traffic Safety Items
Additional Tools and Links
OSHA Heat Safety App
OSHA Occupational Heat Exposure Page
OSHA Heat Illness Prevention Campaign Page
National Weather Service: Heat Index Calculator
NWS Early Heat Index Forecasts Page
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