The Hong Kong government has proposed a new set of air quality standards after a review lasting two years, but Hongkongers have good reason to reject the plan.

These “air quality objectives” set a concentration limit for each air pollutant, and it is the job of the government to ensure our air quality stays within these limits. Unfortunately, the limits have always been much looser than the standards recommended by the World Health Organisation. Among the standards set for five major air pollutants, only one (for nitrogen dioxide) is currently as stringent as the WHO’s guidelines.

At first glance, the new standards – to take effect from 2020 to 2025 – are an improvement from the old. But that’s far from the truth.

One of the most controversial parts in the proposal is a plan to tighten the concentration limit for fine suspended particulates (PM2.5), a pollutant which has been classified as a carcinogen by a WHO agency, while greatly relaxing the number of times in any year that the concentration limits can be exceeded. Under the current standards, PM2.5 is allowed to exceed the concentration limit nine times each year. The government is proposing to increase that number to 35.

Here’s the logic, if you can believe it. In an air quality forecast for 2025, the government projected that the level of PM2.5 would be exceeded 33 times, based on the proposed limit. Hence, the way to ensure all targets are met is to simply allow for plenty of exceptions. So instead of enacting more measures to control emissions, such as encouraging a switch to electric vehicles, the government has found a “short cut” to get Hong Kong to meet its air quality objectives – by allowing exceptions to the standards. How convenient!

We should ask what those extra 26 times could do to public health. Research conducted by the University of Hong Kong in 2011 found that if pollutant limits were allowed to be breached more often, even if the limits were tightened, it could lead to worse pollution.

Government officials have tried to justify their proposal by referring to a WHO guideline that says each country should set and update their own air quality standards while taking into account local circumstances, with an eye to eventually meeting the WHO standards.

Thus, as Secretary for the Environment Wong Kam-sing pointed out in a reply to a legislator’s question in January, setting the number at 35 is “appropriate and in line with international practices, including the EU and the US”. He further said that “air science and health experts” consulted in the review believe that the change on the PM2.5 standards could “help enhance public health protection”.

This is highly debatable. It is true that countries worldwide have different standards when it comes to the number of times air pollutants can exceed set limits. The European Union allows limits for respirable suspended particulates (PM10) to be breached 35 times a year (over a 24-hour period); Australia five times; the US and New Zealand each one time. Some countries don’t allow any breaches.

More importantly, the reason some places allow a seemingly high number of exceptions has to do with the fact they have a large number of monitoring stations. For example, there are 46 general monitoring stations in London, compared to 13 in Hong Kong. According to HKU’s 2011 research, more monitoring stations leads to higher chances of exceeding the concentration limits. That clearly does not apply to Hong Kong’s situation.

If our emissions control policies are effective, the number of times a pollutant exceeds its concentration limit should drop over time. Hence, in each review of the air quality objectives, which happens once every five years, the government should be reducing the number of allowable exceedances, not increasing them. What purpose do the objectives serve anyway, when the number could be increased infinitely?

Without releasing the scientific evidence on the health impact that backs up the proposed adjustment on PM2.5’s, the government’s responses only prove to us the underlying inappropriateness of its proposal and its inaction on air pollution.

To allay public concerns, the government should reveal the health risk assessment results of the two scenarios – a set of air quality objectives with higher concentration limits but fewer allowed exceedances; and a set with lower concentration limits but more exceedances allowed. The public ought to know which scenario is best for their health.

Soon, the government will be consulting the Legislative Council and launching a three-month public consultation on the proposed air quality objectives. To stop air pollution in Hong Kong from worsening and to protect ourselves, our children and vulnerable groups from breathing in more toxic air, the proposal in its current form must not be passed.

If it does get the go-ahead from lawmakers, an amendment bill will be submitted to begin the implementation of the new air quality objectives. The city would then have to suffer from toxic air for at least another five years, until the next review.

Written by / Prima Yu (Campaign Officer)

*The article is also published in Column of South China Morning Post on 18 March 2019

Story posted on
18th Mar, 2019

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