Heat Illness

woman suffering from heat illnessSummer weather means getting outside and having fun or working in the yard, but too much heat can make you sick. Heat waves are the leading cause of extreme weather-related deaths in the United States, and the number of heat-related deaths is rising. From 2010 to 2014, a total of 3,111 heat-related deaths were reported in the U.S. for an average of 622 per year. Averages temperatures are predicted to rise by 1.8 to 5.4°F in the Great Lakes region by the year 2050. This has the potential to cause an increase in extreme heat events and related heat illnesses.  the sun

What causes heat illness?

Your body normally cools itself as your sweat evaporates. But during some extremely hot weather conditions, sweating isn’t enough to cool you. Hot weather conditions can make your body temperature dangerously high, possibly leading to illness or even death.

Who is at risk of heat illness?

Anyone can develop heat illness, but some groups are at higher risk. These groups are:

  • Infants and children up to four years of age
  • Outdoor athletes
  • Adults age 65 years of age and older
  • People without air conditioning in their homes
  • Overweight individuals
  • People who have a serious illness such as heart disease or high blood pressure
  • People who are on certain medications
  • Workers who work outdoors or in hot environments
  • People who live in urban heat islands


What can you do to protect your health?

Illness Symptoms First Aid
Sunburn Red, painful skin, sometimes with blisters Get medical help for infants under 1 year of age with fever, blisters, or severe pain. Use cold compresses or cool water. Apply moisturizing lotion. Do not use salve, butter, or ointment. Do not break blisters.
Heat Rash Red cluster of pimples or small blisters most likely to occur on the neck, upper chest, groin, under the breasts, or in elbow creases Get into a cooler, less humid area. Keep the area dry. Do not use ointments or creams.
Heat Cramps Heavy sweating, muscle pain Stop all activity for a few hours. Drink water, clear juice, or a sports beverage. Get medical help if the cramps do not go away within 1 hour.
Heat Exhaustion Heavy sweating, cramps, fatigue, weakness, headache, cool and moist skin, fast and weak pulse, faint breathing, nausea, fainting Get the person out of the sun, lay them down, and loosen their clothing. Apply cool, wet cloths. Give sips of a cool, non-alcoholic drink. Get medical help right away for an infant, the elderly, or someone who has an existing medical condition. You should also get help right away if the symptoms worsen or last longer than 1 hour. Heat exhaustion can lead to heat stroke.
Heat Stroke Skin that feels hot and dry but not sweaty. Body temperature above 103°F. Rapid, strong pulse. Throbbing, headache, Nausea, confusion, dizziness, unconsciousness. Heat stroke can cause death! Call 911 to get medical help immediately. While waiting, move the person into a shady area. Cool them by putting them in a tub of cool water or shower, spray with cool water from a garden hose, or sponge with cool water. Do not give the person alcohol to drink. If there is vomiting, turn the person on their side to keep their airway open.


Even short periods of high temperature can cause serious, and sometimes life-threatening, health problems. These are steps you can take to avoid heat illness when it’s hot outside.

  • Stay out of the sun.
  • Check your local weather to find out if there are heat-related weather alerts.
  • Never, ever leave anyone or pets in a closed, parked car. Cars can quickly become dangerously hot, even with the windows open.
  • Drink lots of water when it’s hot, even when you are not thirsty.
  • Avoid sugary, caffeinated, and alcoholic drinks. These cause you to lose fluid.
  • Use an air conditioner or go to a cool place such as a cooling shelter, library, or mall.
  • Keep shades and curtains closed to block the sun from coming in your home.
  • Take a cool shower or bath.
  • Wear light-weight, light-color, loose fitting clothes.
  • Limit outdoor activity to the morning and evening hours when it’s not as warm.
  • Wear sunscreen with an SPF of 15 or higher, and that says “broad spectrum” or “UVA/UVB protection” on the label.
  • Ask your doctor if your medical condition or medication could cause you to be affected by hot weather.
  • If your doctor limits the amount of fluid you drink or if you are taking water pills, ask your doctor how much you should drink when the weather is hot.
  • Check on family members, neighbors, or friends that are confined to their home at least twice a day. Move them to a cool place if necessary.

What are heat-related weather alerts?

The National Weather Service issues heat advisories and warnings when the heat index is expected to rise to a dangerous level. The heat index combines high temperatures and humidity to let you know how hot it feels outside.

An excessive heat warning is issued when a heat index of 105°F degrees or higher is expected for 3 hours or more. It is continued when night time temperatures are expected to be around 80°F or higher. The warning is issued within 24 hours of the first day that excessive heat is expected.

A heat advisory is issued within 12 hours of the start of extremely dangerous conditions when the heat index is expected to be 100°F or higher for 3 hours or more. It is continued when night time temperatures are expected to be around 80°F or higher.

An excessive heat watch is issued when there may be an excessive heat event in the next 24 to 72 hours.

An excessive heat outlook is issued when there may be an excessive heat event in the next 3 to 7 days.

What heat illness data are available on MiTracking?

Heat illness data on MiTracking include this indicator:

  • Hospitalizations for heat illness

The data can tell us:

  • The numbers of reported hospitalizations for heat illness
  • The crude rate of hospitalization for heat
  • The age-adjusted rate of hospitalization for heat illness
  • If heat-related hospitalizations are going up or down over time

However, the heat illness data cannot tell us:

  • The total number of people who are affected by heat illness
  • The cost, effect, result, or consequence of heat illness



Centers for Disease Control and Prevention (CDC) and

the Environmental Protection Agency (EPA)

Tips for Preventing Heat-Related Illness

Climate Change and Extreme Heat: What You Can Do to Prepare

Michigan Department of Health and Human Services (MDHHS)

Extreme Heat

Preparing for the Public Health Impacts of Climate Change

Michigan Heat-Related Illness: Syndromic Surveillance Summaries

July 22, 2019

July 15, 2019

July 8, 2019

July 1, 2019

July 9, 2018

July 2, 2018

June 25, 2018

June 18, 2018

June 4, 2018

May 29, 2018

National Institute for Occupational Safety and Health (NIOSH)

Information for Workers

National Weather Service (NWS)

Heat Safety

Occupational Safety and Safety Administration (OSHA)

Occupational Heat Exposure


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