What is Haze?

 

Haze is caused by particulate matter from many sources including smoke, road dust, and other particles emitted directly into the atmosphere, as well as particulate matter formed when gaseous pollutants react in the atmosphere. These particles often grow in size as humidity increases, further impairing visibility and health.

 

Based on National Agency Environment, major components of haze in Singapore are:

 

1) Particulate matter (PM/habuk halus): PM affects more people than any other pollutant. PM10 and below are worse. The major components of PM are sulfate, nitrates, ammonia, sodium chloride, carbon, mineral dust and water. Chronic exposure to particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as of lung cancer.

2) Sulfur dioxide (SO2): This is what gives the haze the acrid smell. It is produced from the burning of peat forests. SO2 can affect the respiratory system and the functions of the lungs, and causes irritation of the eyes. Inflammation of the respiratory tract causes coughing, mucus secretion, aggravation of asthma and chronic bronchitis and makes people more prone to infections of the respiratory tract. Hospital admissions for cardiac disease and mortality increase on days with higher SO2 levels.

3) Carbon monoxide (CO): A gas produced from incomplete combustion. This gas prevents the uptake of oxygen by the blood, which can lead to a significant reduction in the supply of oxygen to the heart, particularly in people suffering from heart diseases.

4) Nitrogen dioxide (NO₂): A reddish-orange-brown gas with an irritating, acrid, characteristic pungent odor. In sunlight, nitrogen dioxide can lead to the formation of ozone, nitric acid and nitrate-containing particles.

5) Ozone (O₃): Ozone at ground level – not to be confused with the ozone layer in the upper atmosphere – is one of the major constituents of photochemical smog. Excessive ozone in the air can have a marked effect on human health. It can cause breathing problems, trigger asthma, reduce lung function and cause lung diseases.

6) Other components present in the haze: Carbon dioxide (CO₂) and water vapor (H₂O)  from the burning.