The haze and your health

While many people may complain about the smell and visibility of the haze epidemic to hit both Singapore and Malaysia – thanks to the heavy smog from forest fires being blown in from Indonesia – this is not the most dangerous thing about the haze.

How does the haze affect our health?

The haze has a detrimental effect on our health

We may all know about the superficial health effects of the haze, such as eye and throat irritation and breathing difficulties, which can easily be solved by moving into an air-conditioned room – away from the hazy environment.

But this is not the only drawback of being exposed to the haze and air pollutants. Depending on the type of particles in the haze, serious, long-lasting detrimental effects to our health can be generated.

Particles in the haze

It is the particulate matter (pm) that lingers in the air, that we should be afraid of, because these may be wedged into our lungs and cause problems – even when the haze does not really appear to be that bad in terms of visibility and smell.

The haze particles come in different sizes, ranging from pm2.5 to pm10. So you should always check not only the PSI reading from the National Environmental Agency (NEA) in Singapore before you go out, but the size of the particulate matter particles or pollutants present in the air as well. This is also from the same NEA website.

The pm2.5 particles

The smaller pm2.5 particles are the most dangerous because they have the ability to travel over thousands of miles and linger in the air for up to days, or even weeks. However, in comparison, the pm10 particles may stay in the air for a few hours only, and these travel only a few hundred yards. So they may not pose as much of a danger.

The larger pm10 particles are more likely to get wedged into the sides of our lungs when we breath them in. They will also be expelled out of the body through our mucus or saliva. So this also makes them less dangerous.

And the pm2.5 particles comprise of entirely different components compared to the larger pm10 particles. The pm2.5 particles are created through the burning of organic compounds and heavy metals whereas the pm10 particles are made when rocks and soil get crushed and grinded up.

pm2.5 particles travel deep into the lungs

As a result of their smaller size, the pm2.5 particles can travel deeply into the lungs and furthermore, due to their composition, they can cause complications over time and through years of exposure. These include lung cancer, lung disease and emphysema and even premature death.

It is dangerous to exercise in hazy conditions

It's dangerous to exercise in hazy conditions. Photo by:

It’s dangerous to exercise in hazy conditions.
Photo by:

Exercising in hazy conditions when the pm2.5 concentration is high, will propel the dangerous pm2.5 particles deeper into the lungs because by exercising, you are breathing much more than normally so that your lungs can get sufficient oxygen. In polluted hazy environments, these deadly and dangerous particles will tag along into your lungs too.

So this means that you should check not only the PSI reading, but also the pm2.5 level too, before you go outdoors for any strenuous exercises. This include running and cycling. And as long as the pm2.5 reading is under 100, then you are all good to go.

So for those indulging in sports, do be careful and take care of your health, during this unfortunate bout of haze.

Click here for tips on how to combat haze and wearing N95 masks, by Ironman triathlete and oncologist, Dr Joanna Lin.

Other blog posts

  • Click here for haze tips from Singapore marathoner and medical doctor Derek Li
  • Click here for how Singapore’s top marathoners have coped with haze
  • Click here for good indoor workouts during the haze
web counter
web counter

Share this page with your friends!


  • You are right Priscilla, the 2.5m particles in the haze is toxic to our health. I would add that you need to protect yourself from the haze not only while exercising but whenever you are outside. Even being outside for a few minutes can cause damage to your body. This is way wearing a N95 mask while outside is important.

    What makes the 2.5m particles difficult to deal with is that most masks are not suited to filter such a small particle size. Even with the use of N95 masks, there is still a high chance of breathing high amounts of the toxins due to improper fitting and use.

    Your recommendation of avoiding exercise while the PSI ratings are above 100 is right on. It can be frustrating to have to adapt our workouts. In the long run, our body will thank us for exercising indoors during this time of year.

    Yours in Health,

    Doctor Emerald

  • denise ho says:

    TQ for writing this.

Leave a Comment