Recently, our island has once again been blanketed by haze that resulted from forest fires from a neighbouring country. While the haze levels are not at health endangering levels, a person who is exposed to hazy environment for a long time can suffer from health problems. When you inhale air which is affected by haze, the particles along with the haze will be deposited in the lungs. The situation will be worse for someone who has a history of respiratory problems such as asthma and chronic lung diseases.Coincidentally, HPB has recently started a campaign to champion for a healthier lifestyle with at least 150 minutes of physical exercise per week! What a bummer! Just when we finally convinced ourselves to take out those dusty running shoes, we worry about whether exercising in the haze is a health hazard itself!
This can be determined by the Pollutant Standards Index (PSI), the smoke levels of haze measured every three hours.
PSI Value PSI Descriptor
0 – 50 Good
51 – 100 Moderate
101 – 200 Unhealthy
201 – 300 Very unhealthy
Above 300 Hazardous
Outdoors exercise should be avoided when the PSI Value is above 100. Hit the gym, work out at home or sweat it out at the community centres and indoor sports facilities instead.
What happens when you exercise outdoors on a hazy day?
Typically, when 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.
This can cause irritation of the upper respiratory tract, respiratory discomfort and reduction in the oxygen transport capacity of the blood.
Smoke inhalation can result in bronchoconstriction (tightening of airways). Penetration of particles into the upper respiratory tract may cause inflammation, congestion or ulceration. As you breathe deeper, harder and more frequently during exercise, such conditions can be triggered.
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.
You should pay close attention to health warnings issued by all advisory boards and follow them as. Before you exercise, tune in to the news, visit http://weather.nea.gov.sg/ForecastToday.aspx or call up the weather station at 6542 7788 to get the latest update on the PSI value. If you have iPhone, you can also get your daily weather forecast, including haze conditions, from the myENV iPhone app.
That said, the current PSI levels which are hovering in the 50s and 60s are still safe for outdoor exercise. You do not have to lay off outdoor exercise completely, and you absolutely have no excuse to hole up at home. Obesity is as much a major health problem as air pollution is!
Other things you can do to battle the haze:
• When outdoors, 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
• Keep the amount of time spent in high pollution areas (like the heavy industrial areas) to a minimum as the side effects are dose dependent
A special reminder to all smokers: Smoking 20 cigarettes per day is about the same as an average 24 hour PSI of 24,000!
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