What you need to know about the haze

What is haze?

According to Dictionary.com, haze is described as "atmospheric moisture, dust, smoke, and vapor that diminishes visibility".

What causes the haze in Singapore?

The haze is caused by the smoke produced by forest fires in Indonesia. Farmers use the traditional method of slash-and-burn to clear land for agriculture. Even though this practice is illegal in Indonesia, weak enforcement means that the ban is largely ignored by its people.

What is Slash-and-Burn?

Slash and burn agriculture has been practised in Indonesia and in many other countries for thousands of years. Small farmers in Indonesia usually carry out this technique to prepare for the cultivation of palm trees, which can be lucrative business as they can be harvested within 6 months of being grown. Burning is the cheapest and quickest way to clear the land. The alternative is to use heavy machinery - which costs about S$300 to clear a piece of land the size of a soccer field - which small farmers could not afford.

Why is the haze unhealthy for us?

Haze may include lethal substances such as carbon monoxide, sulphur dioxide, ozone and lead. These substances when taken into our body system may cause dizzy spells, memory disturbances, irregular heartbeat and damage to the nervous system.

What is PSI?

PSI stands for Pollutant Standards Index. It measures air pollutants such as sulphur dioxide, nitrogen dioxide, ozone, carbon monoxide and particulate matter called PM10 (particulate matter of 10 microns or smaller in size). The PSI value gives an indication of the air quality as shown:

PSI Value PSI Descriptor

0 to 50 Healthy

51 to 100 Moderate

101 to 200 Unhealthy

201 to 300 Very unhealthy

Above 300 Hazardous

Why do we get the haze?

There are mainly two monsoon seasons in Singapore. The Southwest monsoon which occurs from June to September and the Northeast monsoon which occurs from December to March. During the Southwest monsoon (also known as Summer Asian Monsoon), winds blow from Australia and South-east Asia towards India. Since Singapore is located along that path of direction, the haze gets to us as well as countries like Malaysia. Refer to picture below.

Why does the haze seem worse at night?

During the day, the ground is heated by the Sun which causes the air immediately above it to become heated. When this air is warmed, it will become less dense and will rise upwards bringing along the pollutants. At night there is no sunlight to heat the ground so it cools. The air close to the ground also becomes cooler and more dense and will tend to sink together with the pollutants.

How has the haze been affecting you? Leave your comments :)