By
Wan Mohd Shukri Wan Ahmad
Natural Forest
Division, Forest Research Institute Malaysia (FRIM)
Kepong, Kuala Lumpur,
Malaysia
Abstract
Forest fires and the resultant smoke-haze are relatively new experiences to Malaysia. However, the problems seem to be increasing in intensity and recurring periodically. Last year, the haze and forest fires caused a serious environmental problems in Malaysia, Singapore, Brunei and Indonesia. Most of the forest fires reported in Malaysia occurred in degraded or logged-over peat swamp forests, both in the east and west coasts of Peninsular Malaysia and the coasts of Sabah and Sarawak. The extent of peatland destroyed by fires is not known precisely, but a prolonged extremely dry period early in 1998 had exacerbated the resurgence of peat fires over a wide area in Malaysia.
Although peat forest fires in Peninsular Malaysia were not of the same magnitude as in neighbouring Indonesia, they have caused significant damage to property, vegetation, wildlife, environment and public health. Fire has been identified as one of the major threats causing the loss of peat swamp forests in several states in Malaysia. Serious occurrences of forest fires during recent years are due to improper peatland management, slash and burn activities and poor water management, rather than climatic factors such as a long dry spell. The condition is made worse because mitigating measures were not in place and the understanding and technical knowledge in forest firefighting was lacking.
The fires mainly involved peat and beris (heath) forest and bush areas. The fires burned in a slow and patchy manner, but were widespread. The fires spread slowly through the thick peat layers, making it extremely difficult to detect and extinguish them. In such areas, although the surface fires are extinguished, the peat underground will continue to burn unless a large amount of water is used to completely drench the peat layers. Consequently, those involved in extinguishing the fires had a difficult time, because they lacked the necessary tools and experience and they were not trained to handle forest fires. In addition, the remoteness and ruggedness of the terrain exacerbated the problem even further. In many of the affected areas, there were also logistical problems.
The forest fire and haze problems also resulted in government agencies such as the Fire and Rescue Department, Forestry Department and the Department of Environment in Malaysia to seriously re-examine their capacity to deal with wildfires. Relevant measures are being undertaken by these agencies to address the issue. In the long-term, an awareness campaign on the importance of peat swamp forests and forest fire hazards needs to be initiated at all levels by the relevant government agencies. An integrated approach of managing peatlands (agriculture, forestry, aquaculture etc.) is the best solution to avoid serious forest fires from recurring.
Introduction
Various issues related to the conservation of natural resources and the environment have been given much attention lately at the local and international levels. The problems caused by the haze throughout Malaysia and her neighbours, mainly resulting from the rampant fires in various parts of Indonesia since the 1990s, has received much negative publicity. On the other hand, these effects have also improved the awareness of the transboundary nature of the impacts of forest fires, the need for better management of our resources and the need to enhance forestry cooperation within the region.
Forest fires and the resultant haze are still generally considered new problems facing Malaysia. However, their intensity and recurrence have been increasing. In 1997/98, one of the worst episodes of haze struck this region, engulfing Malaysia, Indonesia, Singapore and Brunei. The main source of the haze was attributed to the forest/bush fires that occurred in various parts of Sumatra and Kalimantan coupled with the El Niρo phenomenon, although there were also forest and bush fires reported in Malaysia. At the height of the fire episode about 1000 new fires were recorded by satellite sensors in Indonesia within a two-week period. The Malaysian Air Pollutant Index (API)4 exceeded the hazardous level of 500 in Sarawak, forcing the government to close schools and offices. The haze caused the Malaysian public much discomfort and resulted in disruption to air travel, increased respiratory and related health problems and a significant decrease in tourists visiting the country. Had the haze conditions persisted a little longer, it would have embarrassed the nation and disrupted the prestigious Commonwealth Games that the nation proudly hosted in September 1998.
However, the haze cannot be totally attributed to the forest fires in Indonesia alone as there were also fires reported in various parts of Peninsular Malaysia, Sabah and Sarawak. Many of these fires occurred in degraded peat lands, logged-over forest reserves and secondary state forests. They have caused significant damage to property and loss of valuable timber as well as biological diversity. In this regard, however, there were no detailed studies on the extent and impact of the forest fires undertaken, making it difficult assess the actual situation.
Extent of forest fires in Malaysia
The worst forest fires experienced by Malaysia were in 1982/83 when almost one million hectares of natural forest burned in Sabah. This was at the same time when numerous fires affected Borneo and 3.2 million ha in Kalimantan. However, for Malaysia this was the only case where natural forest fires of this magnitude were ever recorded. Subsequently, forest fires continued to occur in Malaysia but the extent was less and mainly located in secondary conversion forests, forest plantations and degraded forests. Forest fires have been reported as early as the 1970s in the pine plantations and the 1980s in the Acacia mangium plantations. However, many of these fires were not recorded properly. Table 3-3 and Table 3-4 show the occurrences of fires that were recorded in Malaysia beginning in 1992-1997 and 1998 respectively.
Table 3-3 Forest fires in Malaysia 1992-1997.
Year |
Location |
Forest Type |
Area burned(ha) |
Probable Causes |
1992 |
Terengganu |
Acacia Mangium plantation |
265 |
Nearby land clearing and from picnickers at nearby recreational Forest |
Johor |
Acacia Mangium plantation |
3 |
Unknown | |
Selangor |
Acacia Mangium plantation |
10 |
Power transmission undergoing maintenance | |
Pinus Carribaea plantation |
16 |
Adjacent land clearing by villagers | ||
Sabah |
Natural forest |
2 500 |
Cooking by hunters | |
Natural forest |
1 000 |
Arson | ||
Natural forest |
825 |
Nearby land clearing, picnickers and cigarettes | ||
Primary forest reserve |
65 |
Adjacent land clearing by farmers | ||
1994 |
Perak |
Acacia Mangium & Tectona grandis plantation |
333 |
Adjacent land clearing by farmers |
Sarawak |
Acacia Mangium plantation |
15 |
Unknown | |
Plantation (various species) |
50 |
Adjacent land clearing by farmers | ||
1995 |
Selangor |
Degraded peat- swamp forest |
155 |
Adjacent land clearing by villagers |
1996 |
Perak |
Secondary forest |
24 |
Cigarettes |
1997 |
Perak |
Natural forest & FRIM research plots |
22 |
Adjacent land clearing by farmers and hunting |
Pahang |
Natural forest state-owned) |
202 |
Adjacent land clearing for oil palm plantation | |
Peat-swamp forest |
202 |
Adjacent land clearing by villagers | ||
Total |
5 687 |
Table 3-4 Forest fires in Peninsular Malaysia 1998.
Location |
Forest Type |
Area burned (ha) |
Probable Causes |
Kelantan |
Forest plantation |
15 |
Snapped Electrical Transmission lines |
Secondary forest |
240 |
Adjacent land clearing by farmers and private land owners | |
Degraded heath forest |
310 |
Adjacent land clearing by farmers and private land owners | |
Degraded peat forest |
40 |
Adjacent land clearing by farmers and private land owners | |
Selangor |
Forest plantation |
5 |
Cigarettes |
Peat-swamp forest |
250 |
Burning of rubbish by adjacent villagers | |
Perak |
Secondary forest |
60 |
Unidentified |
Peat-swamp forest |
40 |
Hunting | |
Johor |
Peat-swamp forest |
41 |
Unidentified |
Montane forest |
15 |
Unextinguished carbide lamps by mountain climbers | |
Kedah |
Secondary forest |
41 |
Adjacent land clearing by farmers |
Trengganu |
Peat-swamp forest |
900 |
Adjacent land clearing by farmers and private land owners |
Logged forest |
120 |
Unidentified | |
Heath forest |
250 |
Unidentified | |
Freshwater swamp forest |
15 |
Fishing by nearby villagers | |
Forest reserve |
30 |
Adjacent land clearing by farmers and private land owners | |
Pahang |
Peat-swamp forest |
360 |
Land clearing by indigenous people and adjacent farmers |
Forest plantation |
6 |
Unidentified | |
Secondary forest |
61 |
Unidentified | |
Total |
2 799 |
Source: Forest Department Peninsular Malaysia and FRIM statistics.
It is obvious from the above records that incidences of forest fires mainly occurred in forest plantations, degraded peat swamp forests and logged-over forests. The frequency of occurrences also increases appreciably during the El Niρo-Southern Oscillation (ENSO) years where prolonged dry spells are experienced.
Causes of forest fires
Under normal conditions, the undisturbed tropical moist forests of Malaysia and Indonesia will not catch fire easily and even if they do burn, the fire will not be widespread. With an average annual rainfall of about 2 540 mm, humidity exceeding 75 percent and the rate of litter decomposition on the forest floor relatively fast, the climatic conditions are generally humid and fuel build-up on the forest floor is minimal. Unless these conditions are changed, there is very little chance of the forest catching fire. However, when the forest is disturbed and degraded with much debris available on the forest floor and canopy cover opened, the forest becomes more vulnerable to forest fires (especially after a prolonged dry spell). Particularly for the peat swamp forests, the soil is always moist. However, when water in these areas is drained during development projects, the peat becomes completely dry and is very prone to fire. Under these conditions the fire spreads underground and can stay burning for a long time.
The recent prolonged dry spell caused much of the lalang (Imperata cylindrica) and gelam (Malaleuca cajuputi) areas of the secondary beris (heath) forests and degraded peat swamp forests to dry up. Since the soil consists of mainly sand and humus in the beris areas and dried peat in the peatlands, small amounts of rain were not sufficient to retain adequate soil moisture. Most of the smaller rivers had also dried up. In such conditions, these areas are very vulnerable to fire. The sources of the fire are mostly human-cased. Some of the major reasons for the cause of fire are as follows:
Land preparations in establishing agricultural plantations
Land preparation by farmers
Shifting cultivation by indigenous people
Camping and picnicking
Hunting
Snapped electric cable
Natural Causes lightning, spontaneous combustion, etc.
In many cases fires get out of control during burning carried out during establishment of agricultural plantations. The same may also happen when smallholders and farmers undertake land clearing in preparation for the next planting. Improper burning techniques and strong winds may cause the fires to spread to nearby secondary forests. There were also cases where campfires made by campers and hunters were not extinguished properly, resulting in the occurrence of forest fires. Some areas were deliberately burned to facilitate hunting. The burned areas seem to attract game, making them easy targets for hunters.
In Selangor and Kelantan, part of the Acacia mangium plantations were burned because of a snapped high voltage electric transmission cable. In both cases, fortunately, the fire was quickly contained and damage was not extensive.
In Pahang, Sabah and especially in Sarawak, the practice of shifting cultivation by the indigenous people (Orang Asli) is also a major factor contributing to the occurrence of fires.
It is estimated that approximately 65 000 ha. of forest in Sarawak are cut and burned by shifting cultivators. Not only do they degrade valuable prime forestland, their practice of clearing small patches of the forest by burning can sometimes cause widespread damage during the dry spells.
According to the Director of the Fire and Rescue Department (FRD), the awareness among the public, especially in rural areas, on the dangers of open burning during dry periods was clearly lacking. People are not aware that taking the easy path of burning to facilitate land preparation for agriculture can be extremely dangerous. He advised that it would be appropriate that the FRD be consulted before any burning is undertaken, especially during the dry periods.
It was also found that the public is more concerned about the haze rather than the destruction of forests by fires. If forests were burned without causing too much haze in the populated centres, then the outcry would have been far smaller.
Irresponsible cigarette smokers are also a great concern. People who smoke cigarettes often simply throw the butts without ensuring that they have been properly extinguished. A large portion of fires that originated from the roadsides and then spread inwards to the forest reserves are suspected to be caused by smokers who throw unextinguished cigarettes while travelling along the roads.
Impacts
The fires caused extensive damage to vegetation, wildlife, environment and the health of people surrounding the affected areas. The haze and air pollution were at a dangerous level in most of these areas and at times reached unbearable and hazardous levels. Although there were increased respiratory and related ailments, the long term health implications of affected people in the vicinity of the forest fires is difficult to predict and are a cause for concern. Conditions in Peninsular Malaysia and Sarawak became so critical that the Malaysian Government decided to assist Indonesia in putting out the fires. A total of 1 262 firefighters (the largest ever recorded) from Malaysia were deployed to Sumatra and Kalimantan to combat the forest fires.
Areas affected by fire are rapidly colonised by resam and lalang. Consequently, as the fires occur every year, more and more highly rich and varied ecosystems will be replaced by weeds such as resam (Glychenia spp.) and lalang (Imperata spp.). There is a real danger that besides loss of biodiversity, the areas will never be regenerated by trees. The extensive Imperata grasslands in many parts of the Philippines and Papua New Guinea are clear examples. Forest fires have also been identified as a major cause for the loss of peat swamp forests in Malaysia.
Although direct financial estimates due to fires were not available, many hours were spent in fighting fires. This involved personnel from the FRD, State Forestry Department, Police, Drainage and Irrigation Department, Public Defence Department (JPA 3), Public Works Department, Local Town Councils and also members of the community. During the period, air travel was often disrupted, the tourism sector adversely affected and cost of medical treatment for haze related ailments increased.
Other smoke/haze related losses
The 1997 haze reached a critical level, both in terms of intensity and duration, causing much inconveniences and economic disruptions to the Malaysian economy. Other than health impacts, the haze has caused various other quantifiable losses including:
Production losses
The haze in 1997 reached a new urgency in Malaysia when the readings from the Air Pollution Index (API) reached 500. A state of emergency was declared for 10 days in Sarawak. The haze can result in various production losses of economic activities. These haze-related production losses included:
A reduction in crop yields resulting from reduced sunlight. The appropriate method to adopt is a dose response function relating sunlight to yield. Data on sunlight would be needed.
A reduction in fishing effort due to reduced visibility. The fishing days foregone would have to be multiplied by the expected profit per day. A more encompassing evaluation requires the computation of losses in consumer and producer surpluses.
A reduction in industrial and commercial activity due to delays in transportation inputs and outputs; and an increase in cleaning and maintenance of equipment due to dust and corrosion. During production shutdown, profits foregone would have to be estimated.
In principle, as for all damages, estimates should be for profits foregone, not gross value. As a proxy, it is suggested to use days of work lost due to shutdowns at a minimum or average wage.
Tourism losses
Losses incurred by the tourism industry can be estimated by the reduced tourist arrivals from non-ASEAN sources. This is done in order to control for the effect of the 1997 ASEAN economic crisis which in itself is expected to effect incoming ASEAN tourists. Like the case in fishing effort, the losses occurring in August-October 1997 were compared to the "normal" August-October period of 1996. In this way any change in impacts caused by other factors are controlled.
Airline and airport losses
To obtain the losses incurred from airport closures due to poor visibility, estimates of the number of cancelled flights and forgone sales were obtained and multiplied by the airline's average profit rate. Any profits foregone from operation of the airports themselves are then added to the above.
Averting Expenditures
Apart from the loss arising from the haze, the Malaysian Government and firms have incurred averting expenditures to contain the impacts of the haze and to help control the source, i.e. in forest firefighting and cloud seeding operations.
Although the cost of the health impacts is small, the overall impacts from other sectors were quite large. According to the Economy and Environment Program for Southeast Asia (EEPSEA) study, the estimated incremental cost of the haze damage to Malaysia during the months of August to October in 1997 was RM816 million (Table 3-5). The largest component is the productivity losses during the declaration of a 10-day state of emergency in Sarawak. The health impacts contributed only 4.4 percent.
Table 3-5 Aggregate incremental costs of the damage caused by smoke haze.
Type of Damages (1) |
RM Million |
Percentage |
Adjusted cost of illness |
36.16 |
4.43 |
Productivity loss during the emergency |
393.51 |
48.19 |
Tourist arrival decline |
318.55 |
39.02 |
Flight cancellations |
0.45 |
0.06 |
Fish landing decline (2) |
40.72 |
4.99 |
Cost of fire fighting |
25.00 |
3.06 |
Cloud seeding |
2.08 |
0.25 |
Total |
816.47 |
100.00 |
(1) Cost to Malaysian MNCs of RM2.5 million is not included as this amount might have been used by the Government to pay for various avertive expenditures.
(2) Only declining consumer surplus is taken into account as the gain in producer surplus is not a cost.
Source: Mohd Shahwahid and Jamal (1999).
Issues in combating forest fires
In Malaysia, the Fire and Rescue Department is the agency responsible for combating all kinds of fire including forest fires. However, during the combating of forest fires the agency is assisted by other relevant agencies such as the Forestry Department, Public Defence Department, Drainage and Irrigation Department, the police and the local town councils.
The fires that occur in the peat and heath forest/bush areas are relatively slow and patchy but widespread. The fires spread through the forest floor. Thus, even if whole trees were not felled, the root systems could be completely damaged and often the trees would fall and die. In peat lands, the fires spread slowly through the thick peat layers making it extremely difficult to detect and extinguish fires. In such areas, although the surface fires are extinguished, the peat underground will continue to burn unless a large amount of water is used to completely drench the peat layers. Consequently, in peat lands, the most effective way of containing the fires will be by flooding the area.
In Kelantan and Terengganu, the areas that were burned had relatively shallow peat layers. As such, a single heavy rainfall would be sufficient to ensure that the fires are extinguished. Much of the fire that finally came under control in Terengganu was due to some heavy showers that occurred in early May. However, this was not the case for Pahang and Selangor where peat layers were found to be relatively deep. In such conditions, to fully extinguish the surface as well as the subterranean fire, the area would need a continuous heavy rainfall or an artificial flooding with water from nearby sources. The latter method was implemented effectively in Selangor by pumping water from adjacent tin mining pools and rivers.
Although the fires in some areas were put out by the Fire Department, the fires recurred. In such areas, although the fires on the surface were controlled, the peat fire underneath was not fully extinguished. This was also the case for the beris forests. In this regard, the Director of FRD reported that 800 gallons of water had to be used to douse the fire in an area of about 10 square meters. During the dry ENSO period, such large amounts of water is difficult to obtain.
In many of the affected areas, there were logistical problems that arose from poor access. The Fire and Rescue Departments vehicles were designed for structural firefighting and not for travelling in forested areas and thus they were unable to venture into interior areas that were affected by fires. There was a serious lack of water sources to enable the Fire Department to fight the fires effectively. Even in cases where pits and canals were dug, they dried up quickly.
Some of the firefighting equipment used needs to be improved, e.g. the conventional water pumps used were too heavy and could not work for long hours. In Kelantan, however, firefighters tested a new pump provided by Canada. Apparently the pump was not only lighter, it could also work for long hours.
Under such conditions, according to the FRD, the best way to tackle forest fires is to contain them by preventing their spread, especially to sensitive areas and communities. This is undertaken by creating fire breaks.
There is no specific legislation on forest fires under the Malaysian National Forestry act of 1984 (revised 1993). However, there is a provision prohibiting fire-related activities in the permanent reserve forests and there are penalties for such offences. Likewise, the Environmental Quality Act of 1974 explicitly prohibits open burning without a permit to curtail air pollution and the occurrence of haze.
Control Measures
From past trends, the possibility of recurring fires in Malaysia is very likely in the natural and plantation forests. The severity of future fires will depend on weather conditions as well as the awareness and discipline of the public at large. Past experience shows that the possibilities of fires occurring in fire prone areas are very high during ENSO periods. Steps need to be taken to identify these areas and institute prevention and control measures. There seem to be sufficient measures in place to prevent and combat fires in the forest plantations. However, similar measures are grossly lacking for the natural forest areas as managers still view lightly the threat of fires in such forests.
Some of the immediate steps are to ensure that surrounding communities are informed of the detrimental effects of open burning and uncontrolled land clearing practices. There also is a need to adopt conservation measures while in or near the forest, build fire breaks and develop permanent water sources. It will take a combined effort of government agencies, private agencies and others to overcome fire problems in the future. The severity of the 1998 fire season and the involvement of various agencies and the community in fighting the fires should have increased the awareness for the need to take precautionary measures in the future.
Some of the recommended control measures include:
Increasing public awareness
The FRD has an on-going program of creating awareness among the public. However, such programmes need to be improved and intensified. It should also involve other agencies and should reach a wider range of people. This is a long-term, but very effective strategy.
Sustainable forest management
Natural forests that are managed in a sustainable manner, where the structure and overall integrity are not compromised, are very resilient to fires. It is when they are disturbed that they become prone to fire as indicated clearly in the statistics provided in Tables 1 and 2. Most of the secondary and degraded forests that were burned were not forest reserves but state forests that were earmarked for conversion. Often the spread of fire halts when it reaches the undisturbed forests.
Creating buffer zones
There should be an effective buffer zone or fire breaks constructed surrounding Permanent Reserved Forests and State Forests adjacent to agricultural lands and communities. This would help to ensure that the forests are protected from fire which often originate from more populated areas.
Construction of canals
In degraded peat forests where fires are likely to recur, canals should be constructed. The canals could be used to collect water and facilitate firefighting in the future.
Notification of FRD and DOE
In any land preparation involving burning, the FRD and Department of Environment (DOE) will have to be notified for approval.
Development of Forest Fire Squads
The FRD should endeavour to set up a forest fire squad. This squad should have the necessary training and skills in forest/bush firefighting. They should also be equipped with the necessary equipment. The use of suitably equipped helicopters should be further explored. In this regard, initial efforts have already been implemented when training was provided for the FRD in basic forestry knowledge.
Development of Risk Index
Fire prone areas will have to identified and located. An early warning system together with a risk class index should be developed. With such a system, mobilisation of resources could be optimised and targeted to areas with higher risks of fire.
The Forest Fire Prevention and Control Plan
The State Forestry Departments of Peninsular Malaysia have developed a plan on the prevention and control of fires within the natural and plantation forests (Figure 3-5). Each state also has assigned a forestry officer to handle all matters pertaining to forest fires. The plan details precautionary measures to prevent fire in forest areas in natural and plantation forests, allocation of equipment and personnel and forest firefighting protocols. The development of this plan began in 1999 and is an excellent effort undertaken by the Forestry Department.
Rehabilitation of degraded areas
Forest areas affected by fire, be it in the Permanent Reserved Forest or state-owned land, should be rehabilitated quickly to prevent further degradation of the area through soil erosion and colonisation of pioneers and weeds. The burned area needs to be regenerated to restore the area into a productive forest again.
Forest fire research
To date, research efforts have not given sufficient focus into issues related to forest fires. The reason for this may be that in the past no serious fires had occurred in the Permanent Reserved Forest. It is also felt that issues concerning forest fires are mainly social and management in nature. However, the current situation warrants that priority be accorded to undertaking research in order to address such issues as:
Impacts of fires on the forest vegetation and environment.
Water management of peat lands.
Socio-economic implications of forest fires.
Development of zero burning techniques in land preparations for plantations.
Development of fire risk classes and early warning systems.
Networking
The transboundary nature of forest fire problems has suggested a network approach for sharing of information and experience. Networking is a cost-effective mechanism for strengthening institutional capacity, facilitating transfer of technology and enhancing cooperation. For example, Indonesia has more experience in combating forest fires and is also more advanced in research in forest fire management. As such, a country like Malaysia would be able to identify and use some of this knowledge and expertise available in addressing similar issues.
Conclusions
Problems caused by forest fires in the ASEAN region have assumed a new and serious dimension that needs to be addressed sufficiently. Large areas of forestlands have been devastated, resulting in economic losses that run into billions of dollars, degradation of our environment and irreversible losses of valuable biological diversity. The episodes of forest fires and haze in the last two decades, namely in 1982/83, 1990, 1991, 1994 and 1997/98 should serve as useful lessons to be more cautious and undertake all efforts to ensure that we are prepared in the future. The ENSO dry spells will come and the fires will recur. The intensity of the problem will then depend on our state of preparedness to face the crisis, as well as the degree in which we are able to implement the various preventive measures.
Figure 3-5 Forest fire management organization in Malaysia.
References
Goldammer J.G., ed. 1990. Fire in the tropical biota. Ecosystem processes and global challenges. Ecological Studies 84. Springer-Verlag, New York-Heidelberg.
Haron abu Hassan, ed. 1997. Transboundary pollution and the sustainability of the tropical forests: Towards wise forest fire management. Proceeding of the ASEAN Institute of Forest Management International Conference, Kuala Lumpur 2-4 December 1996.
Mohd Puad Dahlan & Tg. Abdullah Tg. Ismail. 1998. Pengurusan Ladang Hutan dan Pencegahan Kebakaran. Paper presented at the Forestry Seminar for the Fire and Rescue Department held at FRIM 22-27 Jun 1998.
Mohd Shahwahid, H.O. & Jamal, O. 1999. Malaysia. Chapter 3, Indonesia's fires and haze: The cost of a catastrophe (D. Glover and T. Jessup, eds.). Singapore. Institute of South East Asian Studies.
Samsudin Musa & Wan M. Shukri Wan Ahmad. 1998. Report on the status of forest fires in Kelantan and Terengganu. Forest Research Institute Malaysia (unpublished).
Source
Wan Mohd Shukri Wan Ahmad. 2001. The forest fire situation in Malaysia. Int. Forest Fire News 26.
4 Malaysian Standard of Air Pollutant Index (API) is measured in ΅g/m3 of air sampled. The scales of the index are categorised as follows: 0-50 = Good; 51-100 = Moderate; 101-200 = Unhealthy; 201-300 = Very Unhealthy; 301-500 = Hazardous.