Haze particles can give rise to acute symptoms such as cough, wheezing, shortness of breath and a feeling of tiredness and weakness. The effect of haze is aggravated in people with pre-existing heart or lung disorders. However, the harmful health effects of a few minutes of haze exposure are temporary and usually do not lead to long-term health issues.
The biggest hazard of the haze is the fine particulate matter (PM) suspended in the air. Particulate matter, especially those of PM2.5 can easily be inhaled into our lungs. This refers to particles that are smaller than 2.5 microns in diameter.
Long-term exposure to the haze and particulate matter can lead to the development of medical conditions such as bronchitis and a higher incidence of lung cancer. Thus it is best to stay indoors during hazy situations when the PSI is at unhealthy levels. If you have to go outdoors for long periods, an N95 mask can help reduce your inhalation of particulate matter.
Those at highest risk of being affected by the haze should remain indoors. These are people with pre-existing heart or lung disorders as exposure to air pollution is known to worsen these conditions. Likewise, children and the elderly who have smaller lung reserves should avoid prolonged exposure to the haze.
Exposure to the haze can lead to symptoms of bronchitis. These symptoms can be just like symptoms of asthma – wheezing, cough, chest discomfort and shortness of breath. If the symptoms are severe, you should consult a doctor immediately. If symptoms are mild, they may abate or resolve with rest (indoors) and avoidance of the haze.
Fine particles are matter foreign to the body (they are like microscopic soot particles). Inhaling the haze is like inhaling smoke – irritation of the sensitive lining within the nose and throat occurs. Symptoms tend to get more serious when the irritation occurs deeper than the nose and throat, especially when the lower air passages (trachea and bronchi) are affected.
If your symptoms are mild and you are healthy, simply avoiding the haze by staying indoors with the windows and doors shut, and turning on an effective air purifier should be sufficient. If your symptoms are more serious or you are unsure how badly you are affected, it is best to consult with a physician.
It is not advisable to self-medicate or use inhalers that you are not familiar with. For example, Seretide is an asthma medication that contains steroids and a long-acting bronchodilator medication. It is a prescription-only medication that is not without adverse effects and it should not be tried without proper medical advice.
Exercising outdoors when the PSI is in the unhealthy range (ie. 100 or more) is counter-productive. The higher the PSI, the more harmful it is to inhale the polluted air when exercising. Note that when you are exercising, you have to breathe harder and the air exchange that takes place in the lungs is several times more than when you are at rest. Therefore, you are inhaling several times more of the air pollution.
Breathing more pollutants into the lungs is in a way negating the beneficial effects of exercise. The most harmful pollutants – the PM2.5 particles can be taken very deep into the lungs and it is difficult for the respiratory system to expel or break down these pollutants. In addition, particles of PM1 are known to bypass the lungs and travel straight into the blood circulation where they can be carried to other organs (such as the brain) with harmful effects.
Every individual is different in size, age and health so it is not possible to say how long a person can tolerate the haze. When the haze level is in the unhealthy range (PSI higher than 100), it is prudent for everyone to avoid outdoor activities.
Usually the harmful effects of a few minutes of haze exposure are temporary and do not lead to long-term health issues.
However, in studies performed in the US and Europe, there was found to be a definite relationship between air pollution and cardiovascular and lung cancer death. The smaller PM2.5 were particularly deadly, with 36% increase in lung cancer rate for every increase of 10 micrograms of PM2.5 per cubic metre.
Clearly then – clean air, just like good health, is invaluable. I think that it's best to avoid air pollution especially when the PSI is very unhealthy. In short, there is no 'safe' level of air pollution. The lower it is, the better for your long-term health.