Haze

Haze is an atmospheric phenomenon where dust, smoke and other pollutant particles obscure the normal clarity of the sky. It occurs when dust and smoke particles accumulate in relatively dry air. When weather conditions block the dispersal of smoke and other pollutants they concentrate and form a usually low-hanging shroud that impairs visibility and may become a respiratory health threat. Dense haze is also known as smog.

Sources for haze particles include farming (ploughing in dry weather), traffic, industry, forest fires and peat field fire.

Seen from far (e.g. approaching airplane), haze is brownish, while mist is more blueish-grey. While haze is formed in relatively dryish air, in more humid air mist is formed, and the haze particles can even act as condensation nucleii for the mist droplets.

Haze in Southeast Asia

Haze is a regular problem in Southeast Asia caused by land and forest fires especially in Indonesia. Those fires mainly affects Brunei, Indonesia, Malaysia, and Singapore. The economic losses of the fires in 1997 have been estimated at US$9.3 billion [1]. This includes damages in agriculture production, destruction of forest lands, health, transportation, tourism, and other economic endeavours. Not included are social, environmental, and psychological problems and long term health effects.

As a reaction, Association of Southeast Asian Nations (ASEAN) signed Agreement on Transboundary Haze Pollution, formed a Regional Haze Action Plan (RHAP) and established a co-ordination and support unit (CSU).