Heat and our Health

Vol. 32 No. 15  The Filipino Journal      Aug. 7, 2018

Kumusta kayo, mga kaibigan!  It has been about a decade (ay!) since I last wrote you in my column, “Ask Dr. Denise”; a lot has happened in that time, so I will re-introduce myself.  My name is Denise Koh, and I am a physician in Winnipeg.  When I was writing Ask Dr. Denise, I had been working on my Masters of Public Health, completing my Community Medicine residency (aka Public Health and Preventive Medicine), and practicing medicine in a number of settings in addition to my full-time training.  Scroll forward 10 years—I completed/achieved my MPH, FRCPC (specialist fellowship designation) and I’ve worked as a Medical Officer of Health in a number of roles.  I currently hold 2 positions with the Manitoba government:  the Chief Occupational Medical Officer and Medical Officer of Health in Environmental Health and Emergency Preparedness.  My biggest achievement is my family:  I am now the proud mom to 4 awesome kids!

So this time I wanted to focus on heat and our health.   You may think this is hardly an issue, since our home country should have that area “cased”, right?  And who wants to worry when we’re too busy celebrating our sunny summers and the end of another long cold winter and slushy flood-y spring??  Well, here are some facts:

- High temperatures combined with high humidity, direct sun and heavy body workload-- particularly without decent air movement--can overwhelm the body’s capacity to cool itself.  This can lead to excessive stress on the body that may result in
     o Heat illness:  heat rash, swelling of hands, feet and ankles, headache, dizziness, upset stomach or vomiting
     o Heat exhaustion:  tired or weak, moist skin, rapid, weak pulse
     o Life-threatening heat stroke:  hot dry skin, rapid, strong pulse, mental confusion, unconsciousness, seizures or convulsions.
- Vulnerable groups at risk include:
     o Older adults
     o Infants and young children
     o People with chronic illnesses (eg. lung, heart or psychiatric illnesses) or who are physically impaired
     o People taking certain medications that affect heat sensitivity by interfering with the body’s cooling functions or water/salt retention (eg blood pressure medications, antidepressants, antipsychotics, anti-Parkinson’s agents)
     o Socially disadvantaged individuals (eg low-income earners, homeless people, people living alone)
     o Newcomers to Canada and transient populations (eg tourists)
     o Certain occupational groups (eg farmers, construction workers, miners, tree planters)
     o Those who are physically active.

Early summer extreme heat events generally result in higher health impacts than those occurring later in the summer.  Most people regularly exposed to high temps become acclimatized or used to hot environments.  Those with heart disease, older adults and young children may not be able to acclimatize as well.  Daily death rates increase when temperatures rise above certain levels.  And it’s worse if high temperatures persist over several days and throughout the night.
 
Temperature projections indicate that the number of days with temps above 30°C in Winnipeg are expected to almost double between 2041 and 2070.  The projected increase in warm nights will also limit nighttime relief from the heat. This is climate change.  Unless we do more to reverse/stop the causes (eg burning of fossil fuels) and adapt to this very real global warming, our health will continue to be at risk.

Being exposured to air pollution and extreme heat is like a double whammy: 
1) High temps increase the formation of air pollutants, such as ground-level ozone.  Forest fires, which occur more often in warmer, dryer weather, also affect air quality.  People exposed to ash and smoke from fires often experience eye and lung irritation, leading to bronchitis. 
2) Reduced lung function or heart rate variability due to ozone or particulate matter pollution can lead to difficulties getting oxygen to our tissues, worsened with increased stress on the heart from high demands on the body to cool itself. 
3) People are likely to spend more time outside or leave their windows open, resulting in an increased exposure to outdoor pollutants

On average 37 kids die in hot cars every year in North America.  The windows in cars act like a greenhouse, trapping the sun’s energy and causing the temperature inside the car to rise quickly.   It’s not just risky during the summer months:  the strengthening sun angle in the spring can cause the temperature in vehicles to spike on a sunny day.  When outside air temperature is 23°C, the temperature inside a vehicle can be extremely dangerous - more than 50°C.  On a hot and sunny day, the temperature inside a vehicle can spike by nearly 20° in just 10 minutes.  Over the course of one to two hours, the temperature inside the vehicle can climb as much as 50° higher than the outside air.   Children heat up three to four times faster than adults.  If a child is small and on the sunny side of the car, death can occur in 15 minutes or under.
- Tips for Parents/Pet Owners:  
     o Never leave children or animals inside a parked vehicle or in direct sunlight.  Always double check before leaving your car; there are apps and a few carseats on the market that apparently are rigged with alarms.
     o Make it a habit to leave your purse, briefcase, cell phone or shoe in your backseat of the car with the child, so you don’t leave without checking the backseat first.
     o If you see a child unattended in a vehicle, call 911 and stay near the vehicle until the police arrive.
     o Pets also have a difficult time cooling off in extreme heat, making hot vehicles dangerous, even when the windows are cracked.

- For workers working in heat:
     o High daytime temperatures can make it challenging to work outdoors or in buildings without AC.  Dizziness/discomfort on the job can lead to incidents and injury.  Manitoba employers must implement safe work procedures and control measures to ensure that the threshold limit values for thermal stress are followed and the worker is provided with information and training in the detection and prevention of injury from thermal stress.
     o SAFEWORK Manitoba has a nifty tip card (https://www.safemanitoba.com/Page%20Related%20Documents/resources/2726_wcb_safe_heat_stress_tip_card_web.pdf) which has a Heat Stress Reference Chart where you can look up the Environment Canada humidex rating of the given day you are working and determine the need for general heat stress controls (give yearly heat stress training, encouraging adequate fluid intake, allow self-limitation of exposure, encouraging workers to watch out for symptoms in co-workers, and adjusting expectations for workers coming back to work after an absence) for unacclimatized workers doing moderate work or specific controls [in addition to general controls, such as engineering controls to reduce physical job demands, shielding of radiant heat, increased air movement, reducing heat and moisture emissions at the source, adjusting exposure times to allow sufficient recovery, and personal body-cooling equipment] for acclimatized workers doing moderate work.  Depending on the humidex, there are requirements in the WSH Act that dictate the length of rest periods (in cool settings) per hour of work based on how strenuous the work is.  There are clothing-adjustment factors for work clothes that restrict sweat evaporation from the skin (eg. water-vapor-impermeable, air-impermeable, thermally insulating, encapsulating suits, multiple layers of clothing).

- Tips for Workers:
     o Wear loose, lightweight, light-coloured clothing.
     o Use fans indoors.
     o Work in the shade and away from other heat sources
     o Take rest breaks in shaded areas and drink cool beverages frequently. 
     o Focus on lighter activities when possible.  Plan the day to tackle the more physically demanding jobs during the cooler morning hours.
     o It takes about a week for the body to adjust to the heat.  Monitor yourself and co-workers, particularly new coworkers for signs of heat illness.
     o Build up tolerance to high temperatures.
     o If you see someone struggling in the heat:
      Move the person to a cool, shaded area.
      Loosen or remove heavy clothing.
      Provide cool drinking water.  Thirst isn’t a good indicator of dehydration, so drink regularly even when not thirsty.
      Call 911 immediately if you think someone is experiencing heat stroke
- Also:  check the weather forecast regularly.  Plan cool-off periods in the day.  Bring cool water and if possible, shade.
- Regularly check up on those who are at risk.
- Don’t forget:  Wear sunscreen at least SPF 15 (anyone older than 6 months).  Reapply frequently.  Wear sunglasses with UVA and UVB protection.

Kung may tinanim, may aanihin; health starts at home. Alagaan ninyo ang katawan at kalusugan ninyo! Take care, and mind your health!