Extreme Heat and Humidity

 

Beat the Heat this Summer

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When both temperature and humidity are high, it can be hard for our bodies to keep cool and not overheat.  Extreme heat events can cause heat-related illnesses and in some cases, even death.  Environment and Climate Change Canada issues heat warnings based on a forecast of:

  • Daytime temperature of 31ºC or higher and nighttime temperature not cooler than 20ºC for at least two days, or
  • Humidex of 40 C for at least two days

Heat warnings mean extra precautions need to be taken by everyone. Some of the usual ways we cool off may not be available this summer because of measures put in place to reduce the spread of the COVID-19 virus. Wearing a face mask when it is hot may require extra breaks from the heat. It will be important to think ahead and plan for ways to stay cool and keep in touch with others who may not be able to stay cool, especially during a heat warning. 

Please check the City of Ottawa's website for opening dates, locations and hours of service at Ottawa.ca.

People at risk of getting sick from the heat include infants and older adults; those who work or exercise outdoors; those with pre-existing health conditions; people experiencing homelessness, and people without access to air conditioning. 

Protect Yourself and Help Others during Hot Weather

  • Drink plenty of water and avoid alcohol and caffeine
  • Avoid heavy outdoor activity
  • Wear a hat, light and loose-fitting clothing, sunscreen and sunglasses when outside
  • Bring an umbrella and water when leaving home in case you need to wait outdoors in the heat, such as waiting to enter a store in a lineup   
  • Cool off in an air-conditioned space when available
  • Cool off in the shade or at a park or greenspace
  • Use a fan and mist your skin with water
  • Take cool baths and showers as often as needed or soak hands and/or feet in cool water
  • Breastfeed according to your child’s cues and drink plenty of water if you are breastfeeding.  See our Parenting in Ottawa website for more info on keeping children safe during hot weather
  • Keep your home cool by closing blinds and curtains  on any windows facing the sun  
  • Open windows at night once the outdoor air is cooler than the indoor air; close windows in the morning before hotter air comes in
  • Use fans at night to help exhaust warm indoor air and bring in cool outdoor air 
  • Talk to your doctor, nurse or pharmacist if you are taking medications as some can make it harder to control body temperature.
  • Stay connected with people in your community who have a difficult time coping with hot weather and those who live alone. Check on them regularly. 

Hot weather concerns and face masks: 

Wearing a mask is important to decrease transmission of COVID-19 in any indoor setting where it may be difficult to maintain at least two-metre distancing or the room or corridor is small. Wearing a mask may not be necessary outdoors (where higher temperatures may be more of a concern) if distances can be maintained. 

Masks do become more uncomfortable in hot temperatures, but they will still work. The general public should plan outdoor outings for the coolest times of the day and take breaks in the shade or a cool environment if they are finding a face mask uncomfortable in the heat.   

For people undertaking physical exertion in heat, a mask can make the effort more difficult. Decreasing intensity/volume of work, more frequent rests, and more cooling breaks may be necessary. Discuss your health needs with your employer. 

For more information visit our website at OttawaPublicHealth.ca/heat or call us weekdays at 613-580-6744.

Stay Healthy During a Heat Warning

Environment and Climate Change Canada (ECCC) issues a heat warning for the City of Ottawa when they forecast the following conditions for two or more days in a row:
  • the temperature will exceed 31°C during the daytime and the nighttime temperature will not be cooler than 20°C, or
  • a humidex of 40 C or higher (feels-like temperature that accounts for moisture in the air)

Heat illnesses are preventable.  Extreme heat can cause dehydration, heat exhaustion, heat stroke and even death. High temperatures can put everyone at risk, but health risks are greatest for:

  • infants
  • older adults
  • those who work or exercise outdoors
  • those with pre-existing health conditions
  • people experiencing homelessness
  • people without access to air conditioning 

Prevent heat related illnesses

  • Drink plenty of fluids throughout the day, preferably water and limit or avoid caffeine and alcohol.
  • Avoid strenuous outdoor physical activity.
  • Limit or avoid direct exposure to the sun.
  • Dress in light and loose-fitting clothing and wear a hat with ventilation holes when in the sun.
  • Look for shade or a cool shelter in an air-conditioned location if available.
  • Never leave children, the elderly or pets unattended in a car, even with the windows open.
  • If you don’t have air conditioning but have one or more large fans:
    • When the outside air is cooler than inside, use a fan in or next to a window to bring in the cooler air from outside, especially from a window on the shaded side of the building. If a second fan is available, use it to blow air out of the home through a different window to help move cooler air throughout the home.
    • If you only have one fan but want cooler outside air to come in to more than one room, open windows in each of the rooms and use the fan to blow air out of a window in another room or hallway – air will be drawn into the home through the other open windows.
    • When it is hotter outside than inside, keep the windows closed and shaded and use a fan to blow air at yourself. Drink lots of fluids so you perspire normally – the sweat evaporates more quickly with air moving over it to help cool you off. Please note this may not be enough when the humidity is very high, it is very hot, or your body doesn’t produce enough sweat – in these situations you may have to seek a cool shelter.
  • Breastfeeding babies/children should be fed following the child’s cues.  Nursing mothers should keep hydrated in order to produce a sufficient amount of milk.
  • Take frequent cool showers or baths.  If you cannot shower or bath easily, sponge often with cool wet towels. Focus on cooling the back of the neck, under the arms and groin area.
  • Soak feet and hands in a basin of cool water. 
  • Stay connected with people in your community who have a difficult time coping with hot weather and those who live alone and check on them regularly.

Where to cool off in Ottawa

Residents and visitors can cool down at City of Ottawa parks and greenspaces.

Heat, air pollution and sun safety

High air-pollution and UV index levels often occur during hot weather conditions. People with breathing and heart problems, and parents and caregivers of children, should pay attention to the hourly Air Quality Health Index

Check the UV index forecast daily at theweathernetwork.comweather.gc.ca or in the local media. Choose a sunscreen and lip balm with an SPF of 30 or higher a wide-brimmed hat, sunglasses and SPF lip balm. 

Additional information

Check out more resources on our website on outdoor air qualitysun safety, and water safety.  Our Parenting in Ottawa website has information about keeping children safe during hot weather and the Ontario Ministry of Labour has information on managing heat stress in the workplace

Call the Ottawa Public Health Information Centre weekdays at 613-580-6744 (TTY: 613-580-9656).

You can also connect with us on FacebookTwitter, and Instagram.

Medical advice 

Contact Telehealth Ontario by calling 1-866-797-0000 for free medical advice.  If it is a medical emergency call 9-1-1 immediately.  

Sign up for weather advisories 

You can now get official weather forecasts and alerts straight to your phone with WeatherCAN, Environment Canada’s new weather application. This app will let you know when a heat warning or other extreme weather is forecast for our region. Download it now! 

 Surviving Summer power outages during heat waves
During heat waves, thunderstorms or a high demand for electricity may result in power outages in your home - affecting your access to air conditioning or electrical fans. Extreme heat is hard on our bodies, which are not acclimatized to hot conditions. Exposure to extreme heat can lead to dehydration, heat exhaustion, heat stroke,

Take the following measures to both prepare for and cope with extreme heat during a summer power outage.

 Preparing for Summer Power Outages
  • Weather-strip doors and windows to keep cool air inside.
  • Cover windows that receive morning or afternoon sun with drapes, shades, awnings or shutters. Outdoor awnings and shutters can reduce heat that enters a home by up to 80 percent.
  • Have on hand materials to make temporary window reflectors. Aluminium foil covered cardboard works well to reflect the heat back outside.
  • Keep storm windows up all year.
  • Have a heat emergency kit available that includes food, water and a battery operated radio and flashlight. Be sure to include food that will not spoil and does not require heating.
  • Think about people who may need help in a heat wave. Make sure they are prepared and able to cope.

Learn more on food safety during a power failure.

 Coping with extreme heat at home during a power outage
Keep your home cool
  • Close all blinds and drapes on the sunny side of your home, but keep windows slightly open.
  • Install temporary window reflectors between windows and drapes, such as aluminium foil covered cardboard. This will help reflect heat back outside.

Keep yourself cool

  • Stay out of the sun and spend time on the lowest floor of your home where it is cooler. Spend at least two hours a day in a cool environment to cool your body during extreme heat.
  • Drink plenty of fluids especially water. Avoid alcohol and caffeine. Eat small light meals.
  • Take frequent cool showers or baths.
  • If you cannot shower or bath easily, sponge often with cool wet towels. Focus on cooling the back of the neck, under the arms and groin area. Soak feet and hands in a basin of cool water.
  • Dress in light and loose fitting clothing.
  • Avoid unnecessary strenuous work or activity outside, especially between 10 and 4 p.m. If work must be done, take frequent water breaks in the shade.
  • Talk with your doctor, nurse or pharmacist if you are taking medications or if you are feeling unwell. Some medications make it harder for your body to control its temperature. Make sure to consult with your doctor if you are on a restricted fluid intake.
  • Listen to the radio or call 3-1-1 for directives about cooling stations and emergency reception centres.

Stay connected and help others

  • Keep in daily contact with friends and family to let them know how you are feeling. Ask for help if the hot weather is making you feel uncomfortable.
  • Check on family, friends and neighbours who may need help coping with the heat, especially those who live alone. People with physical and mental disabilities will need assistance keeping cool.
  • Never leave people or pets in a parked car, even with the windows open. The temperature will rise dangerously in only a few minutes.
 What to do in a heat wave
 Protect yourself
  • Avoid outings and activities during the warmest hours (10 am to 4 pm)
  • Stay in the shade, or consider bringing an umbrella with you
  • Wear light and loose cotton clothing
  • Use sunscreen, and wear sunglasses and a hat outside
  • Take water with you on outings 
  • Shut blinds and curtains of south exposed windows
  • Keep windows shut as long as the outside temperature is hotter than the inside
  • Open screened windows at night to encourage cool airflow
 Keep Yourself Cool
  • Stay inside the coolest rooms in your home
  • If you do not have an air conditioner where you live, use a fan and try to spend time in an air conditioned place for a few hours every day
  • Take cool showers or baths throughout the day and cool your body with a cold washcloth  
  • Soak your feet or hands in cold water to cool your entire body
 Talk With Your Doctor, Nurse or Pharmacist
  • Consult your health care provider, especially if you are taking medications or feeling unwell 
  • Some medications make it harder for your body to control its temperature such as some antidepressants and Parkinson's disease drugs
  • Consult with your doctor if you are on a restricted fluid intake diet He/she will need to adjust this amount during hot weather days
 Drink Lots of Fluids
  • Drink 8 -12 glasses of fluid every day.  Fluids include: water, cold soup/broth, fruits and vegetables high in water content (e.g. melons, strawberries, peaches, peppers and carrots)
  • Avoid or minimize drinking alcohol and caffeinated drinks (coffee, tea, and some carbonated drinks)
  • Eat smaller meals
 Stay Connected
  • Ask for help from a family member, friend, or neighbour if the hot weather is making you feel uncomfortable
  • Keep in daily contact with your friends and family to let them know how you are feeling
  • Reach out to people who have a difficult time coping with hot weather in your community and help them keep cool

Need more info? Call Ottawa Public Health at 613-580-6744

 Effects of Hot Weather
Prepare for hot weather to prevent heat-related illness and death. Our bodies take about two weeks to get used to sudden spikes in temperature. That is how people in hot climates and outdoor workers can tolerate extreme heat while others cannot. . Children, the elderly and the chronically ill are particularly vulnerable to the effects of heat.

Make sure that you and those you care for do not suffer unnecessarily during hot weather events. Check on those who may need help accessing air conditioning, such as the elderly and chronically ill, especially those who live in high-rise buildings. Watch for signs of

  • dehydration
  • heat exhaustion
  • heat stroke
  • sunburn
 Dehydration
Dehydration is caused by the excessive loss of water and salts from the body due to illness or from prolonged exposure to heat. City of Ottawa Paramedics would like to remind you that severe dehydration can easily become a life-threatening condition for infants and the elderly.

Causes:

  • Severe sweating
  • Extreme heat
  • Diarrhea
  • Vomiting
  • Certain medication can cause the body to lose water, and, if not replenished, can accelerate the onset of dehydration

Preventing Dehydration:

  • Drink plenty of fluids throughout the day - more when sweating
  • Avoid strenuous work or sports activities during the intense sunlight hours from 10 a.m. to 3 p.m.

What to look for:

  • Thirst
  • Dry skin
  • Fatigue
  • Light headedness
  • Confusion
  • Dry mouth (mucous membranes)
  • Increased heart rate
  • Increased breathing rate
  • Less frequent urination

Treatment:

  • Move the person to a cool and dry place
  • Have the person lie down and rest
  • Have person drink fluids such as water, juice or sports drinks
  • Monitor the person - especially children and the elderly
 Heat exhaustion
Heat exhaustion is a non-life-threatening condition caused by the excessive loss of water and salts from the body due to prolonged exposure to extreme heat. City of Ottawa Paramedics remind you that continued exposure may lead to heat stroke, which is life-threatening. Young children and the elderly are most susceptible to heat exhaustion.

Causes:

  • Prolonged exposure to extreme heat
  • Loss of body water and salts - usually through sweating
  • Not drinking enough fluids
  • Certain illnesses will also cause heat exhaustion

Preventing Heat Exhaustion:

  • Keep cool - take frequent breaks when working or playing outdoors in extreme heat
  • Wear light-coloured clothes and hat - they reflect heat from the sun
  • Avoid strenuous work or sport activities during the intense sunlight hours from 10 a.m. to 3 p.m.
  • Drink plenty of fluids throughout the day, preferable water. 100% juice or sports drinks also help to keep you hydrated. 

What to look for:

  • Headache
  • Blurred vision
  • Nausea or upset stomach
  • Vomiting
  • Sluggishness or fatigue
  • Thirst
  • Profuse sweating
  • Moderate increase in body temperature

Treatment:

  • Move the person to a cool and dry place
  • Have the person lie down and rest
  • Apply cool water to skin and reapply often
  • Fan the wet skin
  • Have person drink fluids such as water, juice or sports drinks (Gatorade™)
  • Apply ice to head, neck, armpits and groin areas
  • If the person is showing signs of heat stroke call 9-1-1 immediately
 Heat stroke
Heat stroke is a life-threatening condition. City of Ottawa Paramedics would like to remind you to seek immediate medical attention if you, or someone you know is suffering from heat stroke. Heat stroke occurs when the body cannot cool itself, usually by sweating and the internal (core) temperature of the body becomes too high. Children, seniors, outdoor workers and sports enthusiasts are most susceptible to heat stroke.

Causes:

  • The inability of the body to cool itself after prolonged exposure to extreme heat

Preventing Heat Stroke:

  • Keep cool - take frequent breaks when working or playing outdoors in extreme heat
  • Wear light-coloured clothes and hat - they reflect heat from the sun
  • Avoid strenuous work or sports activities during the intense sunlight hours from 10 a.m. to 3 p.m.
  • Drink plenty of fluids throughout the day such as water, 100% fruit juice or sports drinks 
  • Do not drink caffeinated drinks or alcoholic beverages - they accelerate the effects of heat stroke

What to look for:

  • Headache
  • Dizziness
  • Disorientation, agitation or confusion
  • Sluggishness or fatigue
  • Seizures
  • Hot dry skin
  • Increased body (inner) temperature
  • Loss of consciousness
  • Rapid heart beat
  • Hallucinations

Treatment:

  • Call 9-1-1 immediately - heat stroke can be deadly
  • Move the person to a cool and dry place
  • Apply cool water to skin and reapply often
  • Fan the wet skin
  • Apply ice to head, neck, armpits and groin areas
 Sun burn
Sunburn occurs when skin cells that are not protected from direct exposure to the sun are burned. Depending on the length of the skin's exposure the result can range from a mild burning sensation to severe blistering of the affected area. Research shows that repeated overexposure to the sun may lead to various forms of cancer including melanoma. Remember, there is no such thing as a healthy tan.

Causes:

  • Overexposure to the sun
  • Children and people with fair or freckled skin, blue eyes, and light-coloured or reddish hair are generally more susceptible to sunburns
  • Certain medications can cause the skin to burn quicker - talk to your pharmacist about what medications can cause this

Preventing Sunburn:

  • Stay in the shade and avoid the sun between 11 am and 4 pm when the UV Index is 3 or higher  
  • The sun's harmful rays can get through fog, haze and light cloud cover
  • Apply sunscreen and lip balm with a Sun Protection Factor (SPF) or 30 or more that protect against both UVA and UVB rays. Do not apply sunscreen to babies under 6 months
  • Wear a wide-brim hat to protect the face, ears and neck
  • Wear tightly woven clothing including long sleeved shirts and pants to minimize exposure to the sun
  • Pay special attention around water, snow and concrete - they all reflect the sun and will intensify its effects

What to look for:

  • Skin is red, tender and warm to touch
  • Blisters
  • Severe reactions such as fever, chills, nausea or rash
  • Fever or chills
  • Peeling skin several days later

Symptoms may not appear for several hours and the full effect of the burn may take up to 24 hours to occur.

Treatment:

  • Cool compresses, moistened wash cloths placed in freezer, or taking a cool bath will help minimize pain and swelling
  • Apply aloe gel if needed; avoid use of creams or lotions that can hold heat inside the skin or contain numbing medication (i.e. benzocaine or lidocaine). 
  • Pain medications such as Tylenol™ or Advil™ may help to reduce pain and swelling - never give Aspirin™ (ASA) to children
  • Severe sunburn requires medical attention, when in doubt consult your health care provider
 Fan facts

Public Health Ontario - New resource for Long-term care and retirement homes: Use of Portable Fans and Portable Air Conditioning Units during COVID-19 in Long-term Care and Retirement Homes.

DO...

  • use your fan in or next to a window, box fans are best
  • use a fan to bring in the cooler air from outside
  • use your fan by plugging it directly into the wall outlet
  • if you need an extension cord, it should be CSA (Canadian Standards Association) approved

DON'T...

  • don't use a fan in a closed room without windows or doors open to the outside
  • don't believe that fans cool air. They don't. They just move the air around. Fans keep you cool by evaporating your sweat.
  • don't use a fan to blow extremely hot air on yourself. This can cause heat exhaustion to happen faster

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