Clearing the air 

(The Star) – While Malaysia is still using PM10 as a parameter to measure particulate pollution, much of the developed world has moved away from this to something that is even more closely correlated with public health: PM2.5, or particulate matter that is equal to or less than 2.5μm.

There are still no standards here for ultra-fine dust that could be inhaled.

IT happens like clockwork every few months, when the winds do not favour Malaysia: smoke haze gets blown across from Sumatra or Kalimantan to engulf us and we all become very interested in the latest API figures.

The Air Pollutant Index, or API, represents the air quality for the past 24 hours. It is calculated after measuring levels of major pollutants in the air; these include fine dust particles, sulphur dioxide, nitrogen dioxide, ozone and carbon monoxide. These are measured on a continuous basis at 51 locations throughout the country.

We tend to fuss over air quality only when the skies are grey. However, that does not mean that there is nothing to worry about when there is no haze, for research shows that the appearance of the sky is not the only thing to look out for when it comes to determining whether the air is safe to breathe. Much of the hazard is invisible to the eye.

Haze is essentially fine particulate matter which is generated locally, as well as carried into our atmosphere by winds. Up to 2000, the ambient air quality guidelines issued by the World Health Organisation (WHO) did not provide specific guidelines for particulate matter, which can be inhaled by humans.

However, by 2005, WHO revised its guidelines after collating enough evidence that links the fine dust pollution with health effects. The pollutant comes from man-made sources (typically from the combustion of fossil fuels, open burning and various industrial processes, like cement manufacturing) as well as natural ones, which include sea sprays (salt particles), dust carried by strong winds (like during dust storms), and volcanic eruptions.

For a few decades, the most common method of determing particulate pollution is by monitoring levels of fine particulate matter that measure up to 10 micrometers (μm) or 10 microns, commonly referred to as PM10. A micrometer is a millionth of a metre, and the average strand of human hair is about 100μm, while a bacteria measures around 10μm.

Minute particles

While Malaysia is still using PM10 as a parameter to measure particulate pollution, much of the developed world has moved away from this to something that is even more closely correlated with public health: PM2.5, or particulate matter that is equal to or less than 2.5μm.

PM2.5 is regarded as more dangerous because they penetrate deep into the lungs, even reaching the alveoli (air sacs), which is the part of the lungs where the exchange of oxygen and carbon dioxide takes place.

If enough fine particulates get sucked into the alveoli, then the lung function of that person will be impaired, causing shortness of breath, among other complications.

And when these fine particulates accumulate in the alveoli, there is no way for the body to expel them, unlike for larger ones, which can be cleared by blowing the nose or through expectoration.

Research accumulated by the US Environmental Protection Agency (USEPA) has shown that air with high levels of particulates can aggravate symptoms related to asthma, and add further stress on cardiovascular systems.

In severe cases, PM2.5 increases damage to red blood cells in patients with chronic obstructive pulmonary disease.

PM2.5 is now an accepted air quality indicator in many developed countries. For example, the USEPA has set its National Ambient Air Quality Standard limit for PM2.5 at 15 microgrammes per cubic metre of air (μg/m3) for the annual average and 65 μg/m3 for the 24-hour average. The European Union has set 25 µg/m3 (annual average) as a target in 2010.

Getting into the act

Malaysia is rather late in the game when it comes to measuring levels of PM2.5, with the Government getting into the act only last December when five air quality monitoring stations were fitted with equipment to measure fine particulate matter. The stations are in Putrajaya, Banting (Selangor), Cheras (Kuala Lumpur), Langkawi (Kedah) and Kuching (Sarawak).

Not surprisingly, PM2.5 was detected in all five stations. The Department of Environment (DOE) did not reveal the levels but in an e-mail reply toThe Star, said that in urban areas, the ratio between PM2.5 and PM10 was generally above 0.5 while in suburban and rural areas, the ratio was 0.5. In other words, for every gramme of PM10 recorded in urban areas, more than half would consist of PM2.5.

Drawing from available data on PM10, like for example, in Petaling Jaya of Selangor, it can be seen that the city’s long-term mean for PM10 is 36.2μg/m3 – which already fails to meet WHO’s 2005 guideline for PM10, which is at 20μg/m3. By working backwards, it should mean that the levels of PM2.5 should easily exceed 18μg/m3, which again fails WHO’s guideline of 10μg/m3.

A DOE study in 1996 showed that motor vehicles contributed 82% to air pollution, while other significant sources include power stations (9%), industrial fuel burning (5%), industrial production processes (3%), domestic and commercial furnaces (0.2%), and open burning at garbage dumps (0.8%).

Studies by local academicians pointed out that the source of particulate matter in the Klang Valley comes mainly from the transport sector, especially from diesel vehicles. Conventional diesel, while packed with lots of energy, is actually quite a dirty fuel as it contains a high amount of sulphur, which aids in the formation of particulates during the combustion process. Due to the nature of diesel combustion in older types of internal combustion engines, a significant amount of particulate matter is produced, unlike in petrol engines. Hence, it is quite common to see smoke emitted from vehicles or equipment that are powered by diesel such as buses, lorries, locomotives, mobile generators, farm equipment (tractors), construction equipment (concrete mixers, excavators), and even boats.

According to United Nations Environment Programme (UNEP) and the Partnership for Clean Fuels and Vehicles (PCFV), lowering the sulphur content in diesel will allow the introduction of newer emission control technologies that in turn should substantially lower emissions of particulates from diesel engines. (PCFV, a partnership between governments, the private sector and non-governmental organisations, assists developing countries in reducing urban air pollution through the promotion of clean fuels and vehicles.)


To overcome the problem of particulate pollution from diesel, many developed countries are using a cleaner form of diesel called ultra-low sulphur diesel, which generally contains not more than 50 parts per million (ppm) of sulphur (some countries go as low as 10ppm of sulphur).

Malaysia, however, is still using relatively high-sulphur crude oil that it imports, while exporting the more valuable low-sulphur crude. The most recent update of diesel fuel and vehicle emission standards took place in 2009, when Malaysia finally adopted Euro II (already considered antiquated in the developed world – Singapore adopted it back in 2001). The Euro II regime still allows up to 500ppm of sulphur in the diesel to be sold at the pump.

While most Asian countries have adopted the PM10 standard in differing degrees, more is needed in the development of a PM2.5 standard, as well as the tightening of fuel standards. Merely reporting PM10 levels (as in the case of Malaysia) is no longer adequate as it does not give a complete picture of the hazards faced by people.

According to the Clean Air Initiative for Asian Cities (CAI-Asia), an organisation formed to help Asian countries achieve better air quality and more liveable cities, while the phase-out of lead from fuel has been “remarkable”, there has been much feet-dragging when it comes to lowering sulphur levels. It is understood that Malaysia has shifted the implementation date for Euro IV diesel several times, with the latest target moved to 2015.

Among Asian countries, Singapore, Japan and Hong Kong are the most progressive when it comes to using cleaner diesel (Euro IV), while India, China and the Philippines are deemed to be well on their way there. Singapore, which already gives daily reports on PM2.5 levels, will adopt the Euro V standard for new diesel vehicles by January 2014 and will mandate oil companies to sell only near sulphur-free diesel (with less than 0.001% sulphur) by next July.

Beyond measuring and reporting ambient PM2.5 levels, there is also a need to determine the exact sources of these fine particulates. “We need to know how much PM2.5 a bus is emitting per kilometre travelled, or how much PM2.5 is emitted from a factory smokestack,” said air quality researcher Prof Mohd Rashid Mohd Yusof, who heads Universiti Teknologi Malaysia’s Air Resources Research Laboratory.

Undoubtedly, meeting Euro IV targets will entail substantial investments by refineries and oil companies, but the resulting improvements in vehicle emissions will be substantial. Using clean diesel will enable the introduction of the latest high-tech diesel cars from Europe that are equipped with diesel oxidation catalysts (that would otherwise be poisoned by high sulphur levels). Last, but not least, lowering fuel sulphur also makes it possible for some older diesel vehicles to be retrofitted with emission control technologies, and this is a strategy that is used in many urban centres where air pollution is a problem.

On its part, DOE said that it is in the process of developing new ambient air quality standards that will include PM2.5 under its Clean Air Action Plan. “Under the schedule of implementation of the plan, the monitoring of PM2.5 will be incorporated into the existing network of air quality monitoring stations by 2016,” said director-general, Halimah Hassan, in an e-mail statement.

Based on the experience of other countries, it is clear that cleaner air cannot be detached from the tightening of both ambient air quality standards, as well as the mass adoption of cleaner fuels. With the number of vehicles here on the rise, it is only logical for levels of PM2.5 to increase if nothing is done quickly to curb it. Within this context, waiting for another few years seems so awfully far, especially when urban dwellers are forced to breathe in high levels of PM2.5, with or without episodes of haze.