Bears can’t climb trees. Mosquitos are attracted to some people more than others. Wait an hour after eating before swimming. You can’t get a sunburn under water. You may have heard these four summer axioms. Let’s see if the facts support them:

1. Should you climb a tree if you see a bear?

If you’re camping, hiking or spending time at a cottage in the bush, you might well see a bear. If you do, should you run, climb a tree or stand your ground? Ontario’s Ministry of Natural Resources information on what to do if you encounter a bear says:

  • Remain calm. Do not run. Stand still and talk to the bear in a calm voice.
  • If the bear does not get closer to you, slowly back away, talking to the bear in a quiet, monotone voice. Do not scream, turn your back on the bear, run, kneel down or make direct eye contact.
  • If the bear does not leave or approaches you, yell and wave your arms to make yourself look bigger. Throw objects, blow a whistle or an air horn. The idea is to persuade the bear to leave.
  • If you are with other people, stay together and act as a group.
  • Make sure the bear has a clear escape route.
  • Do not run or climb a tree.

This last point is important. “Black bears are extremely fast and can run equally as well uphill or down,” according to the British Columbia Conservation Foundation’s WildSafeBC website.

2. Do you have to wait an hour after eating before swimming?

Many of us remember our parents warning us to wait an hour after eating before swimming, to avoid getting a cramp. Turns out, there’s really no good reason why you can’t cannonball into the pool right after enjoying a burger.

Dr. Richard Fedorak of the University of Alberta’s gastroenterology department said in an interview with CBC News, "That's a myth, and we need to myth bust.” Your parents’ warning was based on the misconception that the process of digestion will use some of the oxygen our muscles need to swim, he explained. In reality, people have more than enough oxygen to go around.

"The simple, average meal isn't going to affect your ability to get into the water," said Fedorak.

3. Can you get a sunburn under water?

It pays to protect your skin even when plunging into the pool on a hot day. According to the World Health Organization’s Global Solar UV Index, “water offers only minimal protection from UV radiation, and reflections from water can enhance your UV radiation exposure.” Sunburn-causing ultraviolet UVB rays are absorbed by water, but you need to be under a lot of it to be protected. Half a metre of water will still let 40% of the UVB through, notes the Hong Kong Observatory’s fact sheet, What You Need to Know about Ultraviolet (UV) Radiation, and the cooling effect of the water makes you less aware of the sun.

And UVA rays, which aren’t absorbed by water, were once thought to be harmless but are now considered a long-term danger, warns the Canadian Centre for Occupational Health and Safety.

If you prefer to stay in the shallow end, your upper body will be exposed to the full force of the sun from above, plus ultraviolet rays reflected from the water’s surface. So slather on that sunscreen and reapply it frequently, as its effectiveness will degrade after doing 10 cannonballs in a row.

4. Are mosquitos attracted to some people more than others?

Are you convinced that mosquitoes treat you as their own private lunch counter while turning up their noses at the people around you? You could be right. Numerous studies have confirmed that these summertime pests are attracted to some people and not others. Researchers have found many causes, including blood type, clothing colour and body temperature. An article posted by the Smithsonian Institute sums up the research:

  • If you have type O blood, you will be a tastier target than those with other blood types.
  • Dressing in dark colours, especially dark blue and black, makes it easier for mosquitoes to locate you by sight.
  • If you’ve been working up a sweat, the lactic acid in your perspiration and the extra carbon dioxide you’re pumping out by breathing hard are both very attractive to mosquitoes.
  • Pregnant women, athletes and beer drinkers all run higher body temperatures than the average person; mosquitoes are drawn to their warmer blood. (Pregnant women also emit more carbon dioxide and have more blood circulating, making them positively irresistible to the little bloodsuckers.)

Whatever advice you receive this summer, it’s important to use your own common sense before following it blindly. Or, better yet, to do a little research of your own.