The haze is pretty much an annual problem here in Malaysia, due mostly to forest fires in Indonesia during the dry season (May-September). That’s when the air pollutant index (or API, rather ironically) readings become important for people to understand what precautions need to be taken.

How is API measured?

Since 1989, Malaysia’s API has been measured by 52 air quality stations throughout the country. They detect the levels of five major pollutants in the air:

1. Sulphur Dioxide (SO2)

2. Nitrogen Dioxide (NO2)

3. Carbon Monoxide (CO)

3. Particulate matter with a diameter of less than 10 micrometers (PM10)

4. Ground Level Ozone (O3)

The index

0-50 Good.

51-100 moderate.

101-200 unhealthy.

201-300 very unhealthy.

> 300 hazardous.

API vs PSI

The pollutant standards index (PSI) is used in Singapore, and it measures the same pollutants, but over a period of three hours. API in Malaysia is based on readings done over 24 hours.

Hazy situation

We’ve had two really dangerous years in Malaysia when the API went off the charts.

September 1997

Sarawak recorded an API of 600, forcing the government to declare a state of emergency. All schools, offices and factories had to be closed, and only essential services such as pharmacies and clinics were allowed to be open for business.

August 2005

The API reading in the Klang Valley reached 500, forcing some schools to close and others to suspend outdoor activities. Port Klang’s North Port was also forced to suspend operations.