The Health Guru

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Should you exercise in smoke haze?

Posted on | October 27, 2010 | No Comments

Recently Singapore experienced it’s heaviest smoke haze since 2006 which led me to research on whether it’s harmful to exercise in such conditions.

Across the island, every 3 hours the smoke levels are measured according to The Pollutant Standards Index (PSI).  On Thursday 21st October at 6pm, they reached a 4 year high of 108 putting levels officially in the ‘unhealthy’ range.

PSI Value PSI Descriptor
0 – 50 Good
51 – 100 Moderate
101 – 200 Unhealthy
201 – 300 Very unhealthy
Above 300 Hazardous

From National Environment Agency website:

Adults breathe an average of 15,000 to 20,000 litres of air every day. Most air, indoor and outdoor, contains some pollutants.

Pollution is usually linked to man-made sources, such as industrial pollution and vehicle emissions.  Like we experienced in Singapore, smoke haze from forest fires also creates intense air pollution.  Burning plant life (Biomass combustions) gives off carbon monoxide, carbon dioxide, methane and particulate matter. Depending on the type of plants being burned, smoke can also contain nitrogen, sulfur and other harmful chemicals.

What does this mean?  You need to listen closely to the health warnings issued by all advisory boards and follow them – as these are truly terrible conditions to exercise in.


On THURSDAY 21 OCTOBER 2010 – From the National Environment Agency: In view of the current haze situation, persons who feel unwell are advised to consult their doctors.  The elderly and those with existing heart or respiratory ailments are advised to reduce physical exertion and outdoor activities.  The public should also reduce vigorous outdoor activity.


Sorry, the news isn’t great from me.  Research has found that a combination of high temperature, humidity and air pollution is the worst combination to increase health risks – which makes Singapore a little incubator for problems as we tick all of these boxes.

Read the research below – but my advice is – avoid outdoors exercise until levels drop to well below 100.  It might be a good chance to use the gym and exercise indoors.

A special note for all of you smokers out there: Smoking cigarettes is far worse than pollution haze. Smoking 20 cigarettes/day is about the same as an average 24 hour PSI of 24,000! This shows how BAD smoking is for our health.

Research:  The most common air pollutants are carbon monoxide, sulfur oxides, nitrogen oxides, ozone, peroxyacetyl nitrate, aerosols, soot, dust and smoke. The effect of these pollutants is related to their penetration into the body. The presence of more than one pollutant or other environmental stressors (e.g. heat, cold and altitude) have a more powerful effect on the body.

As pollutants are inhaled, the main effects are on the respiratory tract. The nose hairs serve as filters and remove large particles and highly soluble gases very effectively, but smaller particles and agents with low solubility pass easily. During exercise, when mouth breathing plays an important role, this air filtration process is much less efficient, and more pollutants reach the lungs.

Exercise performance in pollution causes: Irritation of the upper respiratory tract, Respiratory discomfort and reduction in the oxygen transport capacity of the blood.

Whilst the specific effects of exercising in soot, dust and smoke have not been clearly evaluated, it’s known that smoke inhalation results in bronchoconstriction (tightening of airways), Penetration of particles into the upper respiratory tract cause inflammation, congestion or ulceration.  As you breath deeper, harder and more frequently during exercise, it aggravates and worsens this.

Ozone pollution is the worst:  It’s been found that during light to moderate submaximal exercise lasting several hours, pulmonary function decreases and discomfort increases.  During intense levels of exercise, discomfort can become severe and limit performance.

What you can do:

  • Nose breathing strongly reduces the amount of inhaled pollution compared with mouth breathing.
  • If you are asthmatic, you should avoid exercising in pollution.
  • Avoid exercising in peak / rush hours to avoid too many pollutants in the air.
  • Avoid cigarette smoking
  • Avoid combinations of high temperature, humidity and air pollution.
  • Keep the amount of time spent in high pollution areas to a minimum as the side effects are dose dependent

From American Council on Exercise (Ace) Volume 10 Number 4. June/July 2004

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