CDC | What You Need to Know When the Power Goes Out Unexpectedly

What You Need to Know When the Power Goes Out Unexpectedly

HIGHLIGHTS

To prevent carbon monoxide poisoning, use generators, pressure washers, grills, and similar items outdoors only.
If the power is out longer than two hours, throw away food that has a temperature higher than 40°F.
Check with local authorities to be sure your water is safe.
In hot weather, stay cool and drink plenty of fluids to prevent heat-related illness.
In cold weather, wear layers of clothing, which help to keep in body heat.
Avoid downed power lines, if a power line falls on a car, you should stay inside the vehicle.

Food Safety

If the power is out for less than 4 hours, then the food in your refrigerator and freezer will be safe to consume. While the power is out, keep the refrigerator and freezer doors closed as much as possible to keep food cold for longer.

If the power is out for longer than 4 hours, follow the guidelines below:

For the Freezer section: A freezer that is half full will hold food safely for up to 24 hours. A full freezer will hold food safely for 48 hours. Do not open the freezer door if you can avoid it.
For the Refrigerated section: Pack milk, other dairy products, meat, fish, eggs, gravy, and spoilable leftovers into a cooler surrounded by ice. Inexpensive Styrofoam coolers are fine for this purpose.
Use a food thermometer to check the temperature of your food right before you cook or eat it. Throw away any food that has a temperature of more than 40 degrees Fahrenheit.

For guidelines on refreezing food when the power comes back on, visit the Food Safety and Inspection Service’s page on Food Safety in an Emergency.

The following resources provide additional information on preparing for emergencies and determining if your food is safe after a power outage:

Food Safety After a Power Outage, American Red Cross
Provides tips on safely storing your food and a chart to help you determine if your food is still safe.
Keeping Food Safe in an Emergency, United States Department of Agriculture
Fact sheet and FAQs on food and water safety including guidance on when to discard perishable foods.
Being Prepared, American Red Cross
Comprehensive site on preparing for emergencies including power outages.
Food Safety Office, CDC
Comprehensive food safety information.

Safe Drinking Water

When power goes out, water purification systems may not be functioning fully. Safe water for drinking, cooking, and personal hygiene includes bottled, boiled, or treated water. Your state, local, or tribal health department can make specific recommendations for boiling or treating water in your area. Here are some general rules concerning water for drinking, cooking, and personal hygiene. Remember:

Do not use contaminated water to wash dishes, brush your teeth, wash and prepare food, wash your hands, make ice, or make baby formula. If possible, use baby formula that does not need to have water added.
If you use bottled water, be sure it came from a safe source. If you do not know that the water came from a safe source, you should boil or treat it before you use it. Use only bottled, boiled, or treated water until your supply is tested and found safe.
Boiling water, when practical, is the preferred way to kill harmful bacteria and parasites. Bringing water to a rolling boil for 1 minute will kill most organisms.
If you don’t have clean, safe, bottled water and if boiling is not possible, you often can make water safer to drink by using a disinfectant, such as unscented household chlorine bleach, iodine, or chlorine dioxide tablets. These can kill most harmful organisms, such as viruses and bacteria. However, only chlorine dioxide tablets are effective in controlling more resistant organisms, such as the parasite Cryptosporidium.

To disinfect water:

Filter it through a clean cloth, paper towel, or coffee filter OR allow it to settle.
Draw off the clear water.
- When using household chlorine bleach:
  - Add 1/8 teaspoon (or 8 drops; about 0.625 milliliters) of unscented liquid household chlorine (5–6%) bleach for each gallon of clear water (or 2 drops of bleach for each liter or each quart of clear water). Add 1/4 teaspoon (or 16 drops; about 1.50 milliliters) of bleach for each gallon of cloudy water (or 4 drops of bleach for each liter or each quart of cloudy water).
  - Stir the mixture well.
  - Let it stand for 30 minutes or longer before you use it.
  - Store the disinfected water in clean, disinfected containers with tight covers.
- When using iodine:
  - Follow the manufacturer’s instructions.
  - Store the disinfected water in clean, disinfected containers with tight covers.
- When using chlorine dioxide tablets:
  - Follow the manufacturer’s instructions.
  - Store the disinfected water in clean, disinfected containers with tight covers.

Extreme Heat and Cold

Heat

Be aware of yours and others’ risk for heat stroke, heat exhaustion, heat cramps and fainting. To avoid heat stress, you should:

Drink a glass of fluid every 15 to 20 minutes and at least one gallon each day.
- Avoid alcohol and caffeine. They both dehydrate the body.
Wear light-colored, loose-fitting clothing.
Take frequent cool showers or baths.
If you feel dizzy, weak, or overheated, go to a cool place. Sit or lie down, drink water, and wash your face with cool water. If you don't feel better soon, get medical help quickly.
Work during cooler hours of the day when possible, or distribute the workload evenly throughout the day.

Heat stroke is the most serious heat illness. It happens when the body can’t control its own temperature and its temperature rises rapidly. Sweating fails and the body cannot cool down. Body temperature may rise to 106°F or higher within 10 to 15 minutes. Heat stroke can cause death or permanent disability if emergency care is not given.

Warning signs of heat stroke vary but can include:

Red, hot, and dry skin (no sweating)
Rapid, strong pulse
Throbbing headache
Dizziness, nausea, confusion, or unconsciousness
An extremely high body temperature (above 103°F)

If you suspect someone has heat stroke, follow these instructions:

Immediately call for medical attention.
Get the person to a cooler area.
Cool the person rapidly by immersing him/her cool water or a cool shower, or spraying or sponging him/her with cool water. If the humidity is low, wrap the person in a cool, wet sheet and fan him/her vigorously.
Monitor body temperature and continue cooling efforts until the body temperature drops to 101-102°F.
Do not give the person alcohol to drink. Get medical assistance as soon as possible.
If emergency medical personnel do not arrive quickly, call the hospital emergency room for further instructions.

For more information on heat-related illnesses and treatment, see the CDC Extreme Heat website. Information for workers can be found on the NIOSH webpage Working in Hot Environments.
These resources also provide information about extreme heat:

Heat Stress, NIOSH (National Institute for Occupational Safety and Health)
Comprehensive heat-induced occupational illness and injury information.

Cold

Hypothermia happens when a person’s core body temperature is lower than 35°C (95°F). Hypothermia has three levels: acute, subacute, or chronic.

Acute hypothermia is caused by a rapid loss of body heat, usually from immersion in cold water.
Subacute hypothermia often happens in cool outdoor weather (below 10°C or 50°F) when wind chill, wet or too little clothing, fatigue, and/or poor nutrition lower the body’s ability to cope with cold.
Chronic hypothermia happens from ongoing exposure to cold indoor temperatures (below 16°C or 60°F). The poor, the elderly, people who have hypothyroidism, people who take sedative-hypnotics, and drug and alcohol abusers are prone to chronic hypothermia, and they typically:
- misjudge cold
- move slowly
- have poor nutrition
- wear too little clothing
- have poor heating system

Causes of Hypothermia

Cold temperatures
Improper clothing, shelter, or heating
Wetness
Fatigue, exhaustion
Poor fluid intake (dehydration)
Poor food intake
Alcohol intake

Preventing Hypothermia

Everyone, especially the elderly and ill, should have adequate food, clothing, shelter, and sources of heat.
Blankets can help, even in poorly heated rooms.
In cold weather, wear layers of clothing and a hat, which help to keep in body heat.
Move around. Physical activity raises body temperature.

Water cooler than 75°F (24°C) removes body heat more rapidly than can be replaced. The result is hypothermia. To avoid hypothermia:

Avoid swimming or wading in water if possible.
- If entering water is necessary:
Wear high rubber boots in water.
Ensure clothing and boots have adequate insulation.
Avoid working/playing alone.
Take frequent breaks out of the water.
Change into dry clothing when possible.

Helping Someone Who Is Hypothermic

As the body temperature decreases, the person will be less awake and aware and may be confused and disoriented. Because of this, even a mildly hypothermic person might not think to help himself/herself.

Even someone who shows no signs of life should be brought quickly and carefully to a hospital or other medical facility.
Do not rub or massage the skin.
People who have severe hypothermia must be carefully rewarmed and their temperatures must be monitored.
- Do not use direct heat or hot water to warm the person.
Give the person warm beverages to drink.
Do not give the person alcohol or cigarettes. Blood flow needs to be improved, and these slow blood flow.

For more information about hypothermia, see Extreme Cold: A Prevention Guide to Promote Your Personal Health and Safety.

First Aid for Electrical Shock

If you believe someone has been electrocuted take the following steps:

Look first. Don’t touch. The person may still be in contact with the electrical source. Touching the person may pass the current through you.
Call or have someone else call 911 or emergency medical help.
Turn off the source of electricity if possible. If not, move the source away from you and the affected person using a nonconducting object made of cardboard, plastic or wood.
Once the person is free of the source of electricity, check the person's breathing and pulse. If either has stopped or seems dangerously slow or shallow, begin cardiopulmonary resuscitation (CPR) immediately.
If the person is faint or pale or shows other signs of shock, lay the person down with the head slightly lower than the trunk of his or her body and the legs elevated.
Don’t touch burns, break blisters, or remove burned clothing. Electrical shock may cause burns inside the body, so be sure the person is taken to a doctor.

Power Line Hazards and Cars

If a power line falls on a car, you should stay inside the vehicle. This is the safest place to stay. Warn people not to touch the car or the line. Call or ask someone to call the local utility company and emergency services.

The only circumstance in which you should consider leaving a car that is in contact with a downed power line is if the vehicle catches on fire. Open the door. Do not step out of the car. You may receive a shock. Instead, jump free of the car so that your body clears the vehicle before touching the ground. Once you clear the car, shuffle at least 50 feet away, with both feet on the ground.

As in all power line related emergencies, call for help immediately by dialing 911 or call your electric utility company's Service Center/Dispatch Office.

Do not try to help someone else from the car while you are standing on the ground.

Avoid Carbon Monoxide

For important information about the risk of carbon monoxide poisoning during a power outage, see Returning Home After a Disaster: Be Healthy and Safe, Protect Yourself from Carbon Monoxide Poisoning After an Emergency and Carbon Monoxide Poisoning Fact Sheet (from CDC's National Center for Environmental Health [NCEH]).

Dangers of Gasoline Siphoning

Gasoline may be in short supply, before, during, and after natural disasters, such as hurricanes and floods. When there is not enough gasoline, people may want to take gasoline from one container and put it into another. This can be done by siphoning.

Siphoning gasoline can harm your health. Do not try to siphon gasoline. It can cause serious injury or illness.
Siphoning is when you use your mouth or a pump to suck a liquid such as gasoline out of one container, such as a gas tank, through a funnel or tube and into another container
Possible injuries and illness from any form of siphoning include:
- Burns and injury from unintentional combustion of gasoline and/or gasoline vapors. This may happen if the gasoline or its vapors come into contact with a lit cigarette or static electricity.
- Confusion, drowsiness, headache or problems concentrating from breathing gasoline vapors
- Irritation of skin, eye or mucus membranes on contact
Other possible injuries and illness from siphoning when you use your mouth for suction include:
- Lung damage, if gasoline is inhaled into the lungs (aspiration) during mouth-based siphoning
- Gastrointestinal (GI) signs and symptoms such as nausea, vomiting and stomach pain if any gasoline is swallowed
- Irritation of mucous membranes inside your mouth, throat and stomach on contact
If you do breath gasoline fumes or swallow gasoline and feel ill, see a doctor and/or call the poison center for help at 1-800-222-1222

Safety at Work During Power Recovery

As power returns after an outage, people at work may be at risk of electrical or traumatic injuries as power lines are reenergized and equipment is reactivated. CDC recommends that employers and employees be aware of those risks and take protective steps if they are in contact with or in proximity to power lines, electrical components, and the moving parts of heavy machinery.

More information on electrical safety is available in our fact sheet on Worker Safety in Power Outages or at www.cdc.gov/niosh/injury/traumaelec.html.

Be Prepared for an Emergency

CDC recommends that people make an emergency plan that includes a disaster supply kit. This kit should include enough water, dried and canned food, and emergency supplies (flashlights, batteries, first-aid supplies, prescription medicines, and a digital thermometer) to last at least 3 days. Use battery-powered flashlights and lanterns, rather than candles, gas lanterns, or torches (to minimize the risk of fire).

You can find more information on emergency plans and supply kits in the Emergency Preparedness and You section of our site.

Impact of Power Outage on Vaccine Storage

A power outage has significant implications for vaccine storage. For CDC guidance regarding vaccine storage issues, see Impact of Power Outages on Vaccine Storage.