02 September 2010

A jog in the smog

How does urban pollution affect people who exercise outdoors?

I regularly cycle up Cape Town's Kloof Nek Road in the late afternoon, and regularly fret all the way up the hill about the amount of pollution I’m sucking in. With this weighing on my mind, a couple of mornings ago I got up in the winter gloom and hit the road at about 7:45am instead.

So what’s the answer? Drive everywhere and to hell with the environment? Stay cooped up indoors? Start smoking because you're doing that anyway just by going for a run?

  • Avoid exercising near areas of heavy traffic. Choose quieter roads, parks or sports fields.
  • Early morning and evening (before and after peak traffic i.e. before 7am and after 7pm) are generally the best times for outdoor exercise. Of course, in mid-winter this means being on the streets in the dark; if safety’s a concern then get a group together. But at least do try to avoid exercising in the afternoon, when ozone has had time to form, especially on sunny, hazy, windless summer days.
  • Still winter mornings are also often conducive to higher pollution levels. In some areas, an inversion layer forms: cold air and pollutants get trapped at ground level by a higher layer of warmer air. This effect weakens as the ground heats up during the day.
  • The wind and rain are your friends. Wind can sometimes blow pollution from a fixed source (e.g. a smoke-stack) in your direction, but generally wind is a great help in dispersing pollution. Rain literally washes pollutants out of the air, so post-rainstorm is a good time for outdoor activities.
  • If you must exercise when pollution levels are high, decrease your workout’s duration or intensity, or both – and make up for it on a less polluted day.
  • Remember that outdoor exercise can also include vigorous DIY or gardening, and children’s play.
  • Call your local health department to find out if they do air quality reports, or if they can give you information about when and under which conditions pollution is most problematic in your area.
  • Tobbaco smoke contains many of the same pollutants found in exhaust fumes, in an even more potent form. Reduce your overall pollution exposure by being vigilant about indoor (and 'in-car') pollution too: avoid smoky interiors and sitting behind the wheel in rush-hour traffic. This becomes even more important just before a sports competition or a heavy training session.
  • Give your body a pollution (and stress) break with an occasional weekend in the country.


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