Have you ever headed into an urban center and suddenly realized it felt hotter than the surrounding area? It wasn’t your imagination. This is because of something called the urban heat island effect.
The term “urban heat island” describes built-up areas that really do get hotter than nearby rural areas. The average air temperature in cities with one million people or more can actually be 1°C/2°F to 3°C/5°F warmer than their surrounding areas. In the evening the air temperature difference can be as much as 12°C/22°F.
What causes this effect?
Heat islands can form over any built-up area, but they usually occur over large cities where surfaces often absorb large quantities of radiation from the sun during the day, which is then released at night.
• Built surfaces like roofs, paved roads, parking lots, and sidewalks all absorb solar radiation and release it as heat.
• Vegetation such as trees, shrubs, and climbing plants can help lower the temperature by providing shade and through evaporation.
• When green space is replaced by buildings and paved surfaces this cooling process is reduced and it gets hotter.
• The extra heat in areas with an urban heat island effect can increase the health risk to residents during heat waves.
Tips for staying cool
• Find places to cool off such as shaded areas, public buildings, or shopping malls with air conditioning.
• Look for green spaces like parks and playgrounds that have splash pads, trees, shade structures, and other cooling features.
• Drink plenty of cool liquids even before you feel thirsty – water is best.
• Shade yourself and those in your care by wearing wide-brimmed hats made from breathable material or use an umbrella.
Extreme heat
When the outside air temperature is 23°C/73°F, the temperature inside a vehicle can be extremely dangerous – more than 50°C/122°F. Extreme heat affects young children faster and more dramatically because of their smaller size. Young children (and older adults) cannot regulate their body temperature as efficiently, which leaves them vulnerable to heatstroke.
Heatstroke occurs when our core body temperature reaches 40°C/104°F and this can be fatal. In a small, closed environment like a vehicle, our bodies, especially small or frail ones, can go into shock very quickly causing circulation to vital organs to fail. In other words, it can only take a few minutes to lose someone in our care. It is never safe to leave people and pets inside a vehicle, even with the window down.
