We expect more and more hot days as climate change continues.

It is clear from the events of summer 2021 that heat can be deadly, even in a region with typically mild weather. Heat can sometimes be more dangerous in regions here temperatures are typically mild because people are not acclimatized and buildings are not designed to protect against heat. You can help protect your patients this summer by:

  1. Screening for high risk of heat-related illness
  2. Helping your patients make heat plans
  3. Referring patients to social supports

1. Screening: Risk factors for severe heat-related illness and death

Determine if your patients are extremely high risk for heat: physiologically vulnerable AND socially isolated AND without a reliably cool space. Consider adding “socially vulnerable” in problem list in EMR.

Risk factor


People of all ages can experience significant heat-related illness, but mortality is mostly seen in older adults
Over age 55 – higher risk
Over age 75 – highest risk

Medical factors
Psychiatric illness, neurological disease or substance use disorders, particularly schizophrenia
Cardiovascular comorbidities, diabetes, renal disease, respiratory disease
Medications (see below)
Social isolation
Lives alone (and/or limited family support)
Doesn’t leave home on a daily basis
Need for care
Self-care limitations
Risk is lower if patient is frequently monitored by caregivers
Built environment
No air conditioning*
Lives on top floor and/or in apartment building
Lack of greenery or water body near residence
Economic deprivation
Lives in social housing

*Working air conditioning is a life-saving intervention, and is the external factor most predictive of mortality in vulnerable individuals

Why are older adults at such higher risk of heat illness?

  • For a variety of physiological reasons, older individuals do not dissipate heat as effectively. They also do not perceive heat or dehydration accurately.
  • Physiologic stress likely begins at indoor temperatures >26 C. For susceptible people, >31 C indoors is dangerous.

How will patients know when heat events are coming?

  • The B.C. heat alert system has been slightly updated from previous years. Alerts are issued through Environment and Climate Change Canada, and government/health authorities amplify the messages.

Alert Level

Level One

Level Two

Heat warning
Extreme heat emergency
Public health risk
Moderate (five per cent increase in mortality)
Very high (20 per cent or more increase in mortality)
Very hot
Dangerously hot
Historic frequency
One to three per summer season
One to two per decade

2. Heat plans: helpful factors to discuss with patients

Highlights of heat response physiology

The body’s response to heat stress is to sweat and increase blood flow to skin, which causes increased cardiac output and peripheral skin vasodilation. When people are at rest in high heat, especially if they are having trouble sustaining increased cardiac output, their heart rate may gradually drift upwards. Patients and families may monitor heart rate as one indicator (but not the only indicator) of heat stress.

Newer recommendations on fans

  • New research suggests fans are only useful for cooling for younger people at moderate temperatures.
  • At high temperatures, fans can be counterproductive for older people at serious risk because they improve perception of comfort without reducing physiological heat burden. At temperatures >35 C, fans may actually increase body temperature.
  • Fans should be recommended primarily to move cool air inside in the evening and early morning
  • Tepid water immersion (baths or partial immersion) may be more effective for cooling and can be used in a power outage, as well as misting clothing

Medications that increase risk

  • Beta Blockers
  • Ace medications
  • Calcium channel blockers
  • Vasoconstrictors
  • MAO inhibitors
  • Anti-Parkinson’s drugs
  • Anticholinergics (for COPD, urinary incontinence, or overactive bladder)
  • Diuretics
  • Amphetamines
  • Mental health medications:
    • Tricyclic antidepressants
    • Phenothiazines
    • Lithium
    • Antipsychotics
    • Benzodiazepines
    • Neuroleptics
    • Anxiolytics

How do I counsel for heat risk and support a patient to develop a heat plan?

  • Review signs and symptoms of heat related illness and when to seek medical attention
  • Recommend high risk patients and their caregivers monitor hydration status and temperature of the home (e.g. buy a thermometer to keep in the room)
  • Give recommendations on a home adaptation plan, including air-conditioning or a heat pump, or other home modifications
    • Home modifications may include putting up new or temporary window shades, moving sleeping arrangements to stay in the coolest part of the home, keeping windows closed during hot parts of the day (10:00 a.m. – 8:00 p.m.)
  • Review cooling strategies for someone who is too hot
  • Give recommendations on planning to go somewhere else if the patient doesn’t have air-conditioning, including a cooling centre, another familiar location, or even a cool outdoor green space
  • Encourage patients to set up buddy system or check-in system with friends/family. Family members may monitor heart rate.

Key messages for patients:

  • Pay attention to heat alerts
  • If it is 31 degrees or higher inside, it is dangerously hot and time to go somewhere else
  • Indoor temperatures can peak far later in the day than outdoor temperatures
  • Drink water even if you are not thirsty
  • You need to spend a long time in a cooling centre to benefit – plan to be there for as long as possible (hours or longer)

3. OTHER/SOCIAL SUPPORTS: How can I support high-risk patients?

  • Determine if your staff have the resources and time to ask identified patients if they have a plan in place for hot weather or to call during heat events
  • Some community organizations have “friendly visitors” or perform outreach to their clients during heat events. Some also can provide transportation to cooling centres during heat events.
    • Social Prescribing programs can help make connections (send referrals to local Seniors Community Connectors); patients can also call 211 to be linked to resources. Pathwaysbc.ca also has community-based senior services organizations.
  • Some cooling strategies do not work for all our patients
    • Some patients do not have money to pay for A/C or have homes that have cool spaces
  • The BC Clinical Poverty Tool can help screen for these challenges
    • Ask everyone – it can be difficult to tell or stigmatizing
    • If yes, refer to resources like rent banks or BC Hydro retrofitting assistance programs

Resources for patients and health care providers:

Resources on climate change:

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