A light breeze is all it took to stir up the dust lying in the gutters of Phnom Penh’s Monivong Boulevard on Wednesday and send it flying into the eyes and nasal passages of passersby.
This area, near the intersection with Russian Boulevard in the heart of the city, was used as a monitoring station for a 2006 Jap-
anese study of air pollution in Phnom Penh. And in a startling conclusion to their measurement of the total concentration of suspended particles in the air, the Kanazawa University researchers found that Phnom Penh’s airborne concentration of PAHs, polycyclic aromatic hydrocarbons, was six times higher than that of Bang-
kok, a city once notorious for its smog.
The pollution, the paper concluded, could be traced back to a variety of sources, including diesel smoke from vehicles and generators, kerosene lighting and biomass fuels used for cooking. The study also found that particulate
concentrations in Phnom Penh reached as high as 240 micrograms per cubic meter, compared to Bangkok’s highs of 144 micrograms per cubic meter, as measured by a Thai team in 2008. The majority of those particulates could be traced back to dust.
As surprising as they may be, the Japanese team’s results could also be a reflection of what Bangkok has done in recent years to address its own air pollution problems, and by extension, what Cambodia’s growing cities need to do.
According to reports from the UN’s Economic and Social Commission for Asia and the Pacific, more than one million citizens in Bangkok suffered from illnesses related to air pollution in the mid-1990s.
In response, the Bangkok Metropolitan Administration adopted a slew of new measures to monitor and control air pollution.
To begin with, the city’s pollution control department targeted emissions from cars and motorcycles. They set up checkpoints throughout Bangkok to test emissions from vehicles, making sure that they corresponded to guidelines for carbon monoxide content and carbon particles in black smoke.
Traffic authorities also closed some streets to single-occupant automobiles and even designated a series of vehicle-free streets. The city also expanded its public transit system and added to its green spaces.
Meanwhile, dust was reduced by paving the shoulders of roads and regularly washing down streets during the dry season. Stronger controls were enforced on construction sites; orders were made for tarps to cover loose soil on the ground and in haulage trucks, and vehicles’ tires were hosed off before they entered the streets.
The result of all these initiatives, which were topped off with a public awareness campaign about air pollution, was a 47 percent decrease in the concentration of all airborne particulates during the decade beginning in 1997, according to statistics from Bangkok’s pollution control department.
Although particles of dust might seem like nothing more than a dirty annoyance, they can pick up hitchhikers like bacteria and poisonous chemicals as they travel from the ground into the air and around the city. The dust itself can also irritate the sensitive lining of the lungs and throat.
And some of the PAHs measured in the Japanese study on Phnom Penh’s air quality can also cause cancer after long periods of exposure, according to the US Department of Health and Human Services. Rats and other lab animals have developed lung cancer from breathing in the chemicals, stomach cancer after eating food tainted with them and skin cancer when the toxins were rubbed on their bodies.
Authorities in Bangkok cited human health as the driving force behind the push to improve their city’s air quality, but it’s difficult to discern what Cambodia’s government is doing to improve the quality of the air in Phnom Penh.
Although Cambodia’s Law on Environmental Protection and Natural Resources places the responsibility for pollution monitoring squarely with the Ministry of Environment, it appears to contain nothing that guarantees regular monitoring.
The government has issued a sub-decree entitled “The Control of Air Pollution and Noise Disturbance” outlining carbon emissions standards for vehicles and other sources of pollution, and acceptable ambient levels for a variety of hazardous chemicals.
However, the sub-decree does not spell out how those standards will be enforced. The sub-decree dictates only that “The Ministry of Environment shall regularly control and monitor the situation of the air quality in order to take measures to prevent and reduce air pollution.”
Minister of the Environment Mok Mareth could not be reached for comment. Khieu Muth, secretary of state for the Ministry of Environment, declined to answer questions about what the ministry is doing to monitor and control air pollution.
In a presentation made in May, Kok Sothea, an environmental scientist at the Royal University of Phnom Penh, said that the ministry has in fact established four monitoring stations in Phnom Penh to measure carbon monoxide, sulphur dioxide and nitrous oxide levels, but not lead and other poisonous metals.
But data from those stations is not easily available, and it is not accessible to the public online as it is in Bangkok.
Kok Sothea also doubted the validity of the results of the Japanese studies. Although his own research points to an increase in Phnom Penh’s air pollution in recent years, Kok Sothea said he wants to conduct further studies to verify the Japanese researchers’ findings once he secures the necessary funding.
“The concentration is very high,” Kok Sothea said. “If you compare with Bangkok, Bangkok has a lot of vehicles.”
