Haze is a word not unfamiliar to most Singaporeans. Some can perhaps even recall the severe haze event that led to the closure of primary and secondary schools in 2015 1 . But what exactly is haze?
The Origins of Haze
Haze refers to the smoke, dust, particulate matter and/or other elements floating in the atmosphere that reduces visibility2. In particular, visibility is greatly lowered when sunlight coming into contact with the suspended particulate matter is absorbed or scattered away3.
The haze experienced in Singapore and the wider Southeast Asian region are mostly results of forest fires in Indonesia, as the burning ejects immense amounts of particulate matter into the region’s atmosphere 4 5 6 7.
Fires in Indonesia are predominantly human-induced. Local farmers in Indonesia traditionally practise shifting agriculture with the slash-and burn method, since fires are a cheap and effective way to clear land 8 9 . These practices are not necessarily bad for the environment, if practised sustainably. However, intensification of these agricultural practices in modern times for large-scale cash crop-growing, together with large companies doing the same for their vast oil palm and timber plantations, have caused an increase in fire occurrences and spread 10 11 12.
In Indonesia, where 70% of Southeast Asia’s peatlands are located13, the problem is often worsened when burning takes place in these ecosystems. Peatlands are wetland environments rich in peat soil 14, which is mainly made up of partially decomposed plant materials rich in carbon that are easily combustible in the absence of water 15. Unlike ordinary forest fires, peat fires can spread underground, increasing the difficulty of extinguishing them; they also produce extremely thick smoke haze and can continue for prolonged periods even with rather wet conditions 16 17.
Unfortunately, draining of peatlands to make space for plantations and unsustainable land management have increased the risk of fires in these peatlands 18 19. Together with the often consistent annual land clearance fires in peatlands, fires in Indonesia’s peatlands were often found to be the main contributor of fire activity20 and haze 21 .
Outside of human influences, natural variations in temperature and precipitation patterns can also provide suitable conditions to trigger fires. The El Niño phenomenon which brings hotter and dry weather conditions, can increase risk or spread of forest fires22.
The Impacts of Haze
In Singapore, haze severity is reflected through the Pollutant Standard Index (PSI), calculated based on a 24-hour average reading of the concentration levels of pollutant particles23. Particulate matter less than 10 micrometers in size (PM10) can intrude into the lungs24, while those smaller than 2.5 micrometers (PM2.5) can be particularly harmful as prolonged exposure to high levels have been linked to numerous respiratory diseases 25.
Short term exposure to large amounts of haze particles may cause irritation of the eyes, nose, and throat. However, for children, elderly, and people with chronic lung disease or heart disease, the impacts could be more severe 26. Prenatal exposure to PM can cause low birth weight and foetal death 27. Other components of haze can be just as deadly – with hazardous chemicals like carbon monoxide, sulphur dioxides and many other mostly organic compounds8. In total, the 2015 Haze event was estimated to cause the premature deaths of over 100300 Southeast Asian residents, of which 2200 came from Singapore 29.
Other than negative health impacts, the economy and environment are detrimentally affected as well. With closure of airports and delayed flights, tourism can be severely undermined. Productivity of various sectors are greatly reduced with haze, while accidents occuring due to reduced visibility from haze can also incur substantial damages 30 . Together, these costs can add up to a considerable sum — $16 billion in damages were estimated for Indonesia due to the 2015 Haze event 31.
Environmentally, fires causing the haze can destroy homes and food sources of animals. The haze also affects animals’ health, harming their respiratory systems and reproduction. The thick haze is also found to negatively affect both terrestrial and marine plants, and release of huge amounts of greenhouse gases like carbon dioxide can also be detrimental to the environment at large 32 33.
The Past, Present and Future of Haze
Haze has unfortunately been with Southeast Asia and Singapore for many decades — Singapore was affected by severe haze as early as the 1970s, and the 1997 Haze event with 2 weeks of unhealthy PSI levels brought an estimated S$97.5 million to S$110.5 million economic damages 34.
More recently, pronounced haze was observed in 2013 and 2015. The 2013 event saw a record high PSI of 401 35, leading to high demand for face masks 36 and provision of free ones for the underprivileged by the government 37. The 2015 case had PSI levels above 300 38, resulting in closure of schools mentioned earlier. The FINA Swimming World Cup was also cancelled on some days 39 , and the total loss was estimated at $1.83 billion 40.
Fortunately, conditions have improved considerably in the last few years since 2015. 2019 saw a haze event that was much milder 41, and the overall air quality since 2015 has been consistently healthy and in good ranges 42 43.
This can be attributed to the variety of multinational responses in place over the years to combat the Haze situations, including agreements like the ASEAN Agreement on Transboundary Haze Pollution, and collaborative programmes like the Sustainable Use of Peatland and Haze Mitigation in ASEAN (SUPA) 44. Efforts have also been made to increase information access and improve public participation and awareness, evident in the live regional haze update available and various workshops and events hosted by ASEAN45.
On a national level, Singapore passed the 2014 Transboundary Haze Pollution Act aimed at holding companies accountable for any activities that cause haze pollution in Singapore, and it was first used by NEA against 6 Indonesian firms in 2015 46. Indonesia has also implemented policies to rehabilitate peatlands and impose moratoriums on deforesting. Firms and their leadership teams that were responsible for fires or violation of laws were also arrested 47. As a result, the year 2020 had the lowest rate of deforestation in Indonesia over the past 2 decades, and coupled with La Niña, characterised by wetter conditions in Southeast Asia, Singapore was able to enjoy clear skies in recent years48.
Yet, the story does not end here. Despite improvements, gaps remain to be addressed 49 50 51. The blessed La Niña rainy period is expected to end in the later half of the year, and should drier conditions occur together with increase in fires across the region, haze could possibly return to Singapore once more 52.
On the wider topic of air quality and health, the easily noticeable haze issue perhaps masked the presence of other pollutants in our air. As can be seen from the earlier 2011-2020 Air Quality chart, despite improvements, our predominantly ‘Good’ days pre-2013 have been replaced by mostly ‘Moderate’ days in recent years. One main contributor to this is the domestic transport pollution in Singapore53.
Moving forward, cleaner air for all requires contributions from many different sectors, and resolving issues not only in foreign burning lands, but on our home grounds too. The path to haze-free and clean air is still long, but hopefully, the refreshing respite we had in the last few years may just be the motivation needed to keep us going.
