As a city-state and island, Singapore’s main sources of air pollution are from motor vehicles and industry. However, this is not the source of the infamous and intermittent haze that has at times engulfed the island, making international headlines.
The island of Singapore is surrounded by other island states, including Malaysia and Indonesia, which have large areas of rainforest. In Indonesia in particular, large areas of the forest are often cleared for agriculture, usually by using slash-and-burn practices. Vast swathes of rainforest can be cleared in this fashion – the World Bank reported that 2.6 million hectares of Indonesian forest had been cleared – an area 4.5 times the size of Bali.7 This can create huge volumes of toxic smoke, which not only affects Malaysia air pollution and Indonesia air quality, but can be blown to Singapore by southerly winds. Transboundary smoke has caused a haze of varying severities in Singapore in 1997, 2013, 2015 and 2019. In 2015, Singapore’s air pollution was pushed to hazardous levels from transboundary smoke.
The 2015 haze reportedly cost Singapore $1.83 billion (USD) (an average of $468 per resident) from costs incurred from: millions of residents having to stay at home, disruption to air and sea transportation and public health costs for respiratory, eye and skin conditions.8 The 2015 haze was particularly severe because the weather phenomenon, El Nino, exacerbated the effects of Indonesia’s dry season, further fuelling forest fires.10
Poor visibility in Singapore is not always due to transboundary smoke and can often be due to high volumes of water vapour in the air.9 Poor visibility therefore does not always correspond with bad air quality in Singapore.