The current Sumatran forest fires are producing an unhealthy haze over Singapore which is measured in PSI (Pollutant Standard Index) units. The PSI represents the level of chemical and particulate pollutants in the air.

Fine particulate pollutants measuring 2.5 microns (PM2.5) are especially dangerous to health. These particles are so tiny that they can penetrate into lung tissue. As they may be either solid or liquid droplets, or both; they can carry acids, organic chemicals, toxic metals, bacteria and viruses.

Chemical pollutants include sulphur dioxide, carbon monoxide, nitrogen dioxide and ozone which mayirritate and trigger allergies in the respiratory tract and skin,especially in the vulnerable e.g. children, the elderly, the pregnant and those with exiting chronic lung and heart disease.

These pollutants when breathed in can reduce the quality of our respiration which in turn increases demands on our circulation and heart.

Survival Tips

Here are some simple tips on how best to respond to the haze.

    1. Know your own and family health status. Know which health categories you belong to
      • Healthy
      • Children, Elderly & Pregnant mums
      • Chronic heart and lung disease present
    2. Know the latest PSI levels
      • You can get the latest PSI levels at or
      • Remember it’s the PM 2.5 or fine particles in the air that affects your health most
    3. Know the PSI zone. For simplicity I would suggest 3 main zones* that you can focus on
      • Green (under 100)
      • Amber (between 100 to 200)
      • Red (after 200)


PSI Readings Healthy Elderly, Children and Pregnant Women Chronic Heart and Lung Disease
Green less than 100, Good to Moderate Normal Activities Normal Activities Normal Activities
Amber 101 to 200, Unhealthy What To Do:

  • Hydrate
  • Try exercising indoors
  • Reduce prolonged strenuous outdoor activity eg don’t jog or do manual labour for more than an hour.
  • When physically active take frequent breaks (preferably indoors)
What To Do:

  • Hydrate
  • Exercise indoors
  • Minimal outdoor exposure and physical activity eg going to the playground and park
  • Walking is fine but no running
What To Do

  • Hydrate
  • No strenuous activity
  • Go outdoors only if absolutely necessary
  • When indoorsstay preferably in a room that is air-conditioned or has aHEPA air purifier
Red over 200, Very Unhealthy to Hazardous
  • As above
  • Minimize going outdoors
  • No strenuous outdoor physical activity when PSI >300
  • Wear an N95 mask if you must go outdoors
  • As above
  • Go outdoors only if absolutely necessary
  • If going outdoors take public or private transport eg don’t walk to school or work in the open for long periods
  • Otherwise stay indoors – preferably in a room that is air-conditioned or has a HEPA air purifier
  • Stay indoors when PSI > 300. Wear an N95 mask if you must go outdoors
  • As above
  • Stay indoors when PSI > 200 – preferably in a room that is air-conditioned or has a HEPA air purifier


    1. Know what to do. Some simple things you can do
      • Hydration & boost immunity
        • Drink lots of water during this period to flush out the toxins and reduce throat dryness and susceptibility to upper respiratory tract infection
        • Consider Vitamin C & Zinc supplementation to boost your immunity
        • When staying indoors have the air conditioner or air purifier on. It is probably better to use a HEPA air filter rather than an ionising purifier, the latter may generate more ozone into your environment
        • Wear a N95 mask when going out if the PSI >200


      • Physical Activity
        • Keep exercise and play indoors especially when PSI levels exceed 200
        • This includes even minimally strenuous activities like golf and swimming


      • Medication
        • If you have any known allergies or lung or heart diseases, make sure you have a ready and adequate supply eg antihistamines or asthma medication


    • Consultation
      • If you are feeling unwell or having shortness of breath please see a doctor. It is better to consult a doctor before symptoms worsen. This is especially true in the very young and elderly.

Be aware. Be safe. Be healthy.

Dr. Colin Koh
Family Doctor
Complete Healthcare International

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