Bad haze expected, so new PSI roll-out moved up
By David Ee, The Straits Times, 21 Mar 2014
A triple whammy of factors could mean pollutant levels will hit new highs, the Government said.
It is acting by rolling out the new Pollutant Standards Index (PSI) on April 1 instead of May 1 to give people a better picture of Singapore's air quality. The new PSI will incorporate small, hazardous pollutants called PM2.5 found in haze and emitted by local sources such as vehicles.
The Ministry of Health and Ministry of Manpower have also simplified haze health advisories for the public, and workplace guidelines for employers.
Minister for the Environment and Water Resources Vivian Balakrishnan and the National Environment Agency (NEA) outlined the potential seriousness of the situation to media yesterday.
The three factors are: Singapore being hit earlier by haze this year because of the prolonged dry spell, the worse than usual haze now enveloping Riau and the likelihood of the El Nino weather phenomenon developing, as predicted by most weather models. It is linked to drought in this region.
"At a time when we are... not facing a crisis, I think it is the best time to introduce these changes," said Dr Balakrishnan.
People need information so they can protect themselves, he said, noting that they should should reduce physical exertion, especially outdoors, when air quality is bad. Employers should plan ahead to protect workers.
The north-east monsoon has so far kept haze from Riau away from Singapore, said NEA chief scientific officer Indrani Rajaram. But the south-west monsoon beginning around June could blow it in Singapore's direction.
The Government has also ensured there will be "no shortage of (N95) masks", said Dr Balakrishnan. It has stockpiled 16 million, and retailers have more than 700,000 in stock. "We have to prepare for the worst, but hope for the best," he said. "We have been through this before. We are even more prepared now."
The north-east monsoon has so far kept haze from Riau away from Singapore, said NEA chief scientific officer Indrani Rajaram. But the south-west monsoon beginning around June could blow it in Singapore's direction.
The Government has also ensured there will be "no shortage of (N95) masks", said Dr Balakrishnan. It has stockpiled 16 million, and retailers have more than 700,000 in stock. "We have to prepare for the worst, but hope for the best," he said. "We have been through this before. We are even more prepared now."
ASEAN nations will meet in Brunei next month to try to implement a haze monitoring system that will require Indonesia to share concession maps to pinpoint companies that burn land illegally.
Singapore is negotiating a renewal of its collaboration with Jambi province in Sumatra to help spread sustainable farming practices, said Dr Balakrishnan.
It has also proposed a Transboundary Haze Pollution Bill to hold companies and other entities liable for fires on their land that cause haze in Singapore.
PSI to include PM2.5 levels from May (*brought forward to 1 April 2014)
New index reflects air toxicity better as tiny particles are most harmful
By Feng Zengkun, The Straits Times, 12 Mar 2014
New index reflects air toxicity better as tiny particles are most harmful
By Feng Zengkun, The Straits Times, 12 Mar 2014
The move is timely as it gives a better picture of the toxicity of the air as the PM2.5 can enter people's lungs and blood to cause harm, said experts interviewed.
Minister for the Environment and Water Resources Vivian Balakrishnan said as much when he announced the change in Parliament yesterday.
"This revised single index will reflect whichever of six pollutant parameters is the worst.
Many people had called for more data on PM2.5 last year, during Singapore's worst haze episode, owing to its health impact.
Nanyang Technological University's Professor Ang Peng Hwa, who created the Haze Elimination Action Team Facebook campaign in 2007, said the new PSI "reports more accurately the situation, that PM2.5 is bad for health".The National Environment Agency (NEA) said yesterday that based on the present PSI, each of the past five years had between 91 and 96 per cent of "good" air quality days, and just 4 to 9 per cent of "moderate" days.
NEA said: "There will be no change to normal routines on the ground as people can carry on normal activity if air quality is in the 'good' or 'moderate' range."
The current PSI is calculated from the worst of five other pollutants: sulphur dioxide, ozone, nitrogen dioxide, carbon monoxide and particles called PM10.
Another change taking place in May is that the Government will give hourly updates that are more current on PM2.5 levels in the air.
Now, the updates are given hourly too but are averaged from readings in the previous 24 hours.
With the new hourly and more current PM2.5 updates, NEA will publish a lot more raw data that is useful for academics and scientists, Dr Balakrishnan said.
Last night, the three-hour PSI also crept up to 84 at 8pm, close to the unhealthy range. NEA said it was because of hot spots in southern Johor. The number of hot spots detected in Peninsular Malaysia rose to 149 yesterday from 86 on Monday, while those in Sumatra numbered 259, up from 228, the agency said.
PM2.5 pollutants hit unhealthy level
Yesterday's reading triggers warnings for some to limit outdoor exercise
By Grace Chua, The Straits Times, 13 Mar 2014
Yesterday's reading triggers warnings for some to limit outdoor exercise
By Grace Chua, The Straits Times, 13 Mar 2014
This is even as the main Pollutant Standards Index (PSI) stayed in the moderate range. At 9pm last night, the 24-hour PSI in various parts of the island ranged from 48 to 70.
But PM2.5 levels hit 60 micrograms per cubic m at several points in the afternoon, the highest reading this year. A reading above 55 mcg would be considered unhealthy under a new way of calculating the PSI from May.
At these levels, the elderly, children and those with heart or lung disease should reduce prolonged or heavy outdoor exertion, while everyone else should limit it, said an advisory on the National Environment Agency (NEA) website.
This development comes a day after the Government announced it would incorporate PM2.5 levels into the calculation of the overall PSI starting in May.
PM2.5 are fine particles in the air smaller than 2.5 microns in diameter. Currently, the PSI value is based on the worst of five pollutants, including larger PM10 particles up to 10 microns in diameter.
From May, after PM2.5 becomes a PSI component, yesterday's levels of PM2.5 would translate to a PSI value of 105, in the "unhealthy" range, the NEA said.
Meanwhile, the short-term PSI tends to rise in the evenings and some think the smell gets worse. Without the sun's heat, experts explained, air in the boundary layer of the sky contracts and pollutants within it become more concentrated. The atmospheric boundary layer is the stratum of air closest to the earth's surface, and it expands and contracts as it gains or loses heat.
But while the haze might smell bad, its odour cannot be used to judge how harmful it might be, said Dr Erik Velasco, a research scientist who studies air pollution at the Singapore-MIT Alliance for Research and Technology. "The acrid smell is due to the chemical composition of the pollutants, which depends on the soil, biomass and fire characteristics."
He added: "The intensity of smell cannot be used to quantify the concentration of pollutants in the air. Both visibility and smell are just qualitative indicators."
On Tuesday, the NEA had said the current hazy conditions were due to southern Johor hot spots. The NUS Centre for Remote Imaging, Sensing and Processing also captured images of smoke plumes at plantations near Kota Tinggi in Johor, and its senior research scientist Santo Salinas said: "Because it's extremely dry nowadays, this is something that could have happened accidentally."
There are also hot spots in other parts of peninsular Malaysia and northern Asean, and smoke haze over central Sumatra.
There are also hot spots in other parts of peninsular Malaysia and northern Asean, and smoke haze over central Sumatra.
Short-term exposure to PM2.5 is harmful too
High levels of tiny particles damaging to elderly and children, say experts
By Feng Zengkun and David Ee, The Straits Times, 13 Mar 2014
High levels of tiny particles damaging to elderly and children, say experts
By Feng Zengkun and David Ee, The Straits Times, 13 Mar 2014
WHILE studies have established that prolonged exposure to the pollutant PM2.5 can be highly hazardous, some experts have warned that even short-term exposure can be damaging.
For the elderly, being exposed to high levels of the tiny particles for just an hour can lead to higher risks of heart attacks, a recent study suggested.
One in five children here has asthma and the symptoms may worsen if exposed to high PM2.5 levels for even a few minutes, said research scientist Erik Velasco of the Singapore-MIT Alliance for Research and Technology's Centre for Environmental Sensing and Modelling.
One in five children here has asthma and the symptoms may worsen if exposed to high PM2.5 levels for even a few minutes, said research scientist Erik Velasco of the Singapore-MIT Alliance for Research and Technology's Centre for Environmental Sensing and Modelling.
Experts said this is why the Government's decision to revise its air quality reporting system is timely. From May 1, the National Environment Agency (NEA) will add PM2.5 to its five other pollutants for calculating the Pollutant Standards Index (PSI). This means that if PM2.5 is the most significant pollutant in the air, the PSI figure will be based on it.
The NEA will also begin giving new, hourly PM2.5 updates based on the previous hour's readings. It gives hourly updates now but these figures are based on data in the previous 24 hours and may not reflect the air quality as well at any given time.
PM2.5 particles, which can enter people's lungs, make up the majority of haze particles - as much as 80 per cent during last year's record-busting pollution. They must be watched closely.
The existing PSI is usually based on PM10, which are particles 10 microns or smaller. The Government had said PM10 includes the smaller subset of PM2.5, so an increase in the tiny particles will be reflected in the PSI.
However, experts said PM10 is measured by the weight of the particles per cubic metre of air. This means two pockets of air could both have 100 micrograms of particles - and thus create the same PM10 and PSI values.
But one pocket of air could have fewer but larger particles, while the other could have more of the smaller, more toxic PM2.5 particles.
The NEA reckoned, based on existing PSI calculations, that each of the past five years had between 91 per cent and 96 per cent of "good" air quality days, and just 4 per cent to 9 per cent of "moderate" days.
Under the new reporting system, the figures would have been flipped, with just 1 per cent to 4 per cent of good days in each year, and 92 per cent to 98 per cent of moderate days.
"NEA will have to acknowledge that it was a bit conservative on quantifying the risk posed by the smoke," said senior research scientist Santo Salinas at the National University of Singapore's (NUS) Centre for Remote Imaging, Sensing and Processing.
The NEA's PSI health advisories for moderate and good air are the same. They state that all people, even the vulnerable, can carry on normal activities unless they feel unwell. However, scientists said the vulnerable should take extra care when air quality is moderate.
Dr Salinas welcomed the new, more current hourly PM2.5 updates, which will be provided alongside the 24-hour averages. "A 24-hour average smooths out pollution spikes," he said. "It is not a good indicator for rapid reaction, for example, for people who work outdoors."
Dr Christopher Frey, chair of the United States Environmental Protection Agency's clean air scientific advisory committee, explained that the first generation of PM2.5 monitors needed to accumulate almost a full day's worth of particles to be useful.
Instruments that can measure PM2.5 over shorter time frames are a "relatively recent introduction" so there have not been enough health studies to reach a firm conclusion on the short-term exposure impact, he said.
Dr Velasco stressed: "There is no evidence of a safe level of exposure or threshold, below which no adverse health effects occur."
Some complained during last year's haze that NEA figures - averaged over periods longer than an hour - did not seem to match what was outside their windows.
Dr Frey said the new one-hour index will "change more quickly and be more consistent with people's observations of visibility reduction".
Nanyang Technological University Professor Ang Peng Hwa, who created the Haze Elimination Action Team Facebook campaign in 2007, said the new changes "were made in response to science". He added that the new system may highlight pollution generated here, which could signal the Government to take action.
Assistant Professor Harvey Neo of the NUS Department of Geography said: "Some people will get a sense that this was a long time coming, or feel they have been cheated for the past few years.
"But most would welcome the changes... I would see this as (the Government) trying to match reality better."
Pushing for higher air quality
A new stricter Pollutant Standards Index (PSI) will result in Singapore having more "moderate" air quality days from May, down from "good". What does this mean for Singaporeans? And can air quality be improved further?
By Feng Zengkun, The Straits Times, 20 Mar 2014
A new stricter Pollutant Standards Index (PSI) will result in Singapore having more "moderate" air quality days from May, down from "good". What does this mean for Singaporeans? And can air quality be improved further?
By Feng Zengkun, The Straits Times, 20 Mar 2014
A NEW Pollutant Standards Index (PSI), to kick in from May, will expose the country's less-than-ideal air quality. Under this new, higher standard, more days will be deemed "moderate" and fewer days deemed "good". This is because the new PSI will be expanded and is expected to be largely based on the prevalence of tiny and more hazardous pollutants called PM2.5 in the air.
PM2.5 refers to particulate matter up to 2.5 micrometers or microns in size. These particles are known to cause inflammatory responses both in the respiratory tract and blood vessels. Previously, the incidence of PM2.5 was not directly taken into account when determining the index.
Such particles generally come from activities that burn fossil fuels.
Nanyang Technological University's Professor Ang Peng Hwa was one of several experts who said that if "moderate" air quality becomes the norm here, pressure will be put on local polluters to improve their standards.
That norm would tell people that "at least some of this poor air quality is domestically generated, for example from urban traffic, and not all from fires in Indonesia. That could signal the Government to act on this," he said.
Comparing cities
HOW does Singapore's air quality compare with other cities?
Some experts such as National University of Singapore's (NUS) Assistant Professor Jason Cohen, who is studying how climate change and haze interact, said the level of air pollution in Singapore during non-haze periods is common in many cities. Even haze such as that seen this year is also not unusual.
Other researchers found that during 2007, Singapore's annual PM2.5 level was sandwiched between those of Los Angeles, Tokyo and London, which were better, and Hong Kong, Berlin and Mexico City.
Prof Cohen said, however, that Singapore's annual average may disguise peaks and troughs caused by seasonal monsoon, rain and fires, while other cities such as New York may have more consistent levels throughout the year.
In 2010, a United States-based air pollution research body, the Health Effects Institute, released a report showing that pollution in major Asian cities exceeded World Health Organisation (WHO) standards.
Like other cities, in recent years, Singapore's air quality standards have fallen below WHO guidelines for three other city-related pollutants - sulphur dioxide, ozone and PM10 (particulate matter up to 10 microns in diameter).
Local polluters
WHILE air quality is determined in part by one's geographical neighbourhood, experts say local polluters play a big role too.
The local emitters of sulphur dioxide, PM10 and PM2.5 include motor vehicles, refineries, power stations, shipping and other industries, said NEA.
Many of these same sources also emit nitric oxide, nitrogen dioxide and hydrocarbons which can also lead to ozone being formed.
Sulphur dioxide is a toxic gas, contributes to acid rain and helps to form PM2.5, while ozone and particulate matter pose respiratory risks.
To be fair, the Government has acted swiftly to raise air quality, especially targeting the worrisome sulphur dioxide, PM10 and PM2.5 pollution.
Diesel vehicles make up about half of all PM2.5 emissions in Singapore. Since January, all new diesel vehicles here have to meet tighter emissions standards. A higher standard for new petrol vehicles will kick in from April, while those for new motorcycles and new scooters will be tightened from October.
More incentives were also announced earlier this month to encourage diesel vehicle drivers to switch to more environmentally friendly models. Since last year, industries and motor vehicles here can use only diesel with less than 0.001 per cent sulphur.
The NEA said these and other measures also help to reduce the compounds that lead to ozone. These compounds form "an important fraction" of PM2.5, so their reduction will have additional benefits, said experts. Another major source of sulphur dioxide emissions is refineries. The NEA works with the Economic Development Board to reduce sulphur dioxide emissions from refineries.
The NEA's data showed that three refineries here made up 71 per cent of sulphur dioxide emissions in 2012. They are Shell, ExxonMobil and Singapore Refining Company (SRC).
Shell and ExxonMobil representatives said the firms had invested in new technology and improved operations over the years to reduce their emissions, and will continue to do so. SRC's upgrading plans include a facility to treat the petrol it produces to under 0.005 per cent sulphur.
An ExxonMobil spokesman said its investments had already helped avoid 215,000 tonnes of emissions each year in the past five years. He added that energy is crucial to society.
Minister for the Environment and Water Resources Vivian Balakrishnan said last week that Singapore's power plants have also increasingly switched to using cleaner natural gas.
All these efforts will help Singapore meet several interim WHO standards by 2020. It also aims to meet the WHO final standards at some unspecified point in future.
The way ahead
WHILE these steps are laudable, experts had suggestions for more improvement, particularly in the study of PM2.5. "A good next step (after the new PSI) would be to have the chemical and size breakdowns of the PM2.5 here," said NUS's Prof Cohen.
Knowing what makes up the tiny PM2.5 particles will make it easier for Singapore to determine when its neighbours are imposing the pollution and when local sources are the culprits, he said.
Singapore should also study the chemical processes that take place in the air. While vehicles emit PM2.5 directly, they also emit gases that interact with other airborne pollutants to create new PM2.5.
Research scientist Erik Velasco, from the Singapore-MIT Alliance for Research and Technology's Centre for Environmental Sensing and Modeling, said understanding Singapore's atmospheric chemistry will enable the Government to act to limit the prevalence of such particles.
Dr Velasco had also previously said that air quality management must also take into account seasonal shifts in weather patterns, such as the annual south-west monsoon.
Regional distribution of the pollutants also matters. The NEA now divides Singapore into five regions and gives updates on the six pollutants - PM10, PM2.5, carbon monoxide, ozone, sulphur dioxide and nitrogen dioxide. For instance, more than half of sulphur dioxide emissions here come from refineries located in the south-west, either on the mainland or offshore. When the wind blows from that direction during the monsoon, residents in those areas could be affected.
While Singapore's hands may be tied when it comes to foreign pollution, there is much it can do for itself.
Once the new PSI kicks in, Singapore will likely have many more days classified as "moderate", rather than "good". This could serve as a rallying point for the Government and the community to press for higher air quality standards. If that happens, everyone in Singapore will breathe a little easier.
How the new index works
What is the new Pollutant Standards Index (PSI)? Why will it result in Singapore having more days of "moderate" air quality rather than "good"?
The new PSI index adds tiny, hazardous particles called PM2.5 to its current five "criteria pollutants".
The five pollutants currently used are sulphur dioxide, ozone, carbon monoxide, nitrogen dioxide and PM10. The last refers to particles 10 micrometres or microns - about one-seventh the diameter of a strand of human hair - or smaller.
PM2.5 is a subset of PM10. It refers to particles 2.5 microns or smaller. They are considered dangerous because they can get into people's lungs to wreak harm.
The five pollutants currently used are sulphur dioxide, ozone, carbon monoxide, nitrogen dioxide and PM10. The last refers to particles 10 micrometres or microns - about one-seventh the diameter of a strand of human hair - or smaller.
The pollutant's levels here have exceeded World Health Organisation (WHO) air quality guidelines in six of the past seven years, partly due to the recurrent haze. Figures for last year are not available yet.
PM2.5 can be emitted by forest fires, vehicles, power plants, refineries, ships and aircraft, and to a lesser extent by construction and land reclamation. Many of these activities are found in Singapore and in cities in general.
Under the new PSI rules, the index will be based on whichever of the six pollutants is the most dangerously concentrated in the air. This is expected to be PM2.5.
The Government says the prevalence of PM2.5 in the air will probably set the new index "almost all of the time". This means many more days will be classified "moderate".
If the new PSI had been adopted, Singapore's air quality would have been "moderate", not "good", for over 90 per cent of the days for each of the past five years.
Based on the existing PSI, 91 per cent to 96 per cent of the days in each of the last five years had "good" air, and 4 per cent to 9 per cent had "moderate" air quality.
If the new PSI had been used, there would have been just 1 per cent to 4 per cent of "good" days in each year and 92 per cent to 98 per cent of the days would have had "moderate" quality air.
After "good" and "moderate", air quality worsens to "unhealthy", "very unhealthy" and "hazardous".
Clearing the air over PM2.5 purifiers
By Andy Ho, The Sunday Times, 6 Apr 2014
From this month, Singapore's air quality will, more often than not, be classified in the "moderate" range.
By Andy Ho, The Sunday Times, 6 Apr 2014
That's because on April 1, the old Pollutant Standards Index (PSI) was tweaked to incorporate the 24-hour concentration of PM2.5, the smallest polluting particles.
This is particulate matter (PM) of 2.5 microns in diameter or less, a micron being a millionth of a metre. (The human eye can see particles as small as 40 microns or the diameter of human hair.)
PM2.5 is so tiny that it penetrates deep into and gets embedded in lung tissue to cause or aggravate various lung and heart diseases. This is because particulate matter is actually made up of solid or liquid droplets, or both, carrying acids, organic chemicals, toxic metals, bacteria and viruses.
By contrast, the PM10 that was reported in the PSI in the past comprises larger particles of between 2.5 and 10 microns in diameter. These are trapped only in the nose and throat, and so they get removed when we cough, sneeze or swallow.
Thus, while they can irritate the upper airways, they don't damage the lungs. So health-wise, PM2.5 matters, not PM10.
You can check the real-time air quality over different parts of Singapore at aqicn.org as well. This international site has always included PM2.5 and, in the first three months of 2014, it reported "good" air quality for only a few parts of Singapore and for just a few days. For almost all the hours of all the days, most parts of Singapore had only "moderate" air quality - even without forest fires in Sumatra causing us grief.
The NEA said recently that people can carry on normal activities if air quality is in the "moderate" range. But if prevention be the better part of valour, people should avoid outdoor activities when the air quality is "moderate".
You know people are worried when you find no air purifiers left on the shelves. Demand has risen seven-fold since January compared with the same period last year, according to big retail chains such as Courts and FairPrice.
But are portable air filters that claim to remove particulate matter from indoor air worth the money? They sell for anything from $300 to $1,700.
But are portable air filters that claim to remove particulate matter from indoor air worth the money? They sell for anything from $300 to $1,700.
There are two types of such devices.
Less common these days are electronic cleaners that spray out charged ions into the air. These ions attach themselves to PM in the air, giving it a charge. When thus charged, PM will stick to surfaces like walls or furniture.
These air cleaners are less popular as they may produce ozone, which damages the lungs.
Most units sold here now are mechanical air filters that come with high efficiency particulate air (Hepa) filters. The filter media are made of microscopic glass fibres that can remove almost all PM2.5, which sticks to the fibres.
Units that cost a bit more may include an activated carbon filter to remove gases and odours.
Most also have a fan to circulate the cleaned air. This can be noisy but research indicates that the fan has to be turned on fully - at its noisiest - to be of benefit. Conversely, units marketed as being silent because they have no fan are typically less effective.
What about health benefits?
Doctors tend to ask patients with asthma or allergies to use Hepa air filters, but there is no good evidence that they significantly affect health outcomes in these or other conditions such as chronic heart or lung disease.
In a review of studies, the Institute of Medicine - a non-profit organisation that is part of the United States National Academies and provides independent advice on health issues - said it was not possible to draw "firm conclusions regarding the benefits of air cleaning for asthmatic and allergic individuals".
The institute, which relies on scientists who volunteer to do the studies that are subjected to a formal peer-review system, said it was also not clear that cleaning the air would even be highly effective in reducing symptoms per se.
In a 2008 study published in the official journal of the Pittsburgh-based Air and Waste Management Association, researchers concluded that if a portable Hepa air cleaner was used, any effectiveness was limited to a single room and not the entire dwelling. So it was "not likely" to help asthmatic patients because of their exposure to allergens in other rooms where no cleaners were running.
That study also indicated that building Hepa filters into the ductwork of a centralised air conditioning system for an entire home was more likely to be of benefit than portable air cleaners.
For most of us lesser mortals, however, portable air cleaners will have to do. If you do decide to get one, check its efficiency and effectiveness first.
Efficiency tells you how much airborne PM it can remove. If its efficiency is 99 per cent, it removes 99 per cent of the PM in the air that passes through it.
Most units nowadays claim 99 per cent efficiency.
Its effectiveness tells you how much it can reduce PM within a specified space. This depends on the unit's efficiency, of course, but also the volume of air it has to deal with.
For example, if the cleaner can process only 10 cubic metres of air per minute, it is 10 times less effective than one that can process 100 cubic metres per minute.
But most academic studies do not identify air cleaners by brand. If you want to know the effectiveness of different brands, the best resource is the searchable directory at www.cadr.org (run by the Association of US Home Appliance Manufacturers).
A recent study of the air filters identified by brand on this website found that those with moderate-to-high effectiveness ratings were sufficient for home use where PM was the main concern.
But once you've picked the portable unit you want, note that where you place it can affect its effectiveness too. Make sure that its air intake and output are not blocked by furniture, walls or other obstructions.
Also, for the best results, all the doors and windows of the room must be closed, so that means you will need to run the air conditioner as well.
Finally, Hepa filters need to be regularly cleaned and periodically replaced. But be careful not to release the PM back into the air when you do so. Handle the filters gently, don an N95 face mask when washing them and dispose of your old filter media in plastic bags with a tight knot.
Finally, Hepa filters need to be regularly cleaned and periodically replaced. But be careful not to release the PM back into the air when you do so. Handle the filters gently, don an N95 face mask when washing them and dispose of your old filter media in plastic bags with a tight knot.
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