Category: Air Quality

Tung Chung ozone worse, but PM2.5 has improved

The ozone level in Tung Chung has worsened in the last five years, but the presence of all other major pollutants has declined, according to government figures.

Air quality data released to Legco today show ozone levels increased 9% between 2013 and 2017, but level PM2.5 particulates fell 19% and  sulphur dioxide is down 36% (see below).

Responding to a question from People Power member Raymond Chan, Environment Secretary Wong Kam-sing said the high ozone level was a result of “the influence of regional pollution.”

Chan said a number of Tung Chung residents had told him they felt local air quality had deteriorated in recent months and feared the opening of the Macau bridge would make the air even worse.

But Wong said apart from ozone, the level of air pollutants in Tung Chung was within government air quality targets.

Source: EPD

But he admitted that no assessment of the air quality impact of the HK-Macau bridge had been made since 2009. The 30-kilometre main bridge is due to open in May.

Wong said a Highways Department study prior to construction had concluded that “air quality at sensitive receivers in the vicinity” of the bridge would comply with government targets.

He said there was no plan to further review Tung Chung air or the effects of traffic crossing the new bridge.

But he said the EPD would continue to monitor the air quality across Hong Kong, including Tung Chung, and was also reviewing the current air quality objectives (AQOs).

Tung Chung facing more hazardous air over weekend

After pollution readings reached dangerous levels yesterday, Tung Chung is facing further hazardous air over the weekend – unless rain can clear the skies.

Readings from both the World Air Quality Index, also known as AQICN, and the Hong Kong government Air Quality Health Index (AQHI) hit hazardous levels yesterday.

Tung Chung recorded on the AQICN chart of ‘very unhealthy’ for four hours, which it describes as ‘emergency conditions’ in which all people are urged to stay indoors.

The AQHI showed Tung Chung reaching the ‘serious’ level, for six hours up to 7pm yesterday evening – one of six locations around Hong Kong to do so.

Tung Chung air, Wednesday (AQHI)

AQICN says that while today is likely to be merely ‘unhealthy for sensitive groups,’ it predicts extended periods of ‘unhealthy or very unhealthy’ over the weekend and Monday.

More bad air (AQICN)

The AQHI forecast is for “low to very high” risk today.

In a statement issued 11am yesterday EPD called on children and elderly to stay indoors and for the general public to avoid strenuous outdoor activity:

Higher than normal levels of nitrogen dioxide and particulates have been recorded in the territory since early this morning. Hong Kong is being affected by an airstream with higher background pollutant concentrations. In addition, light wind hinders effective dispersion of air pollutants. Sunshine enhances photochemical smog activity and the formation of ozone and fine particulates, resulting in today’s high pollution in the vicinity of Hong Kong. The high level of ozone has promoted the formation of nitrogen dioxide, particularly in parts of the urban areas and at the roadside.

However, it noted that the pollution levels could ease with the rain patches predicted for Friday.

At 9:30am Tung Chung air was rated moderate on the AQICN index.

Earlier this week the EPD released data that showed the number of unhealthy air days last year had nearly doubled over 2016. The department attributed this to warmer weather and lower cloud cover, making it easier for ozone.

After weekend of bad air, fresh winds forecast to lift Tung Chung haze

After a weekend of bad air, relief for Tung Chung residents may come as early as tonight with the arrival of fresh east or northeasterly winds.

For almost all of the weekend PM2.5 concentrations in Tung Chung and across the city were recorded at the ‘unhealthy’ level by the ACQI air quality index.  At that level active everyone, “especially children, should limit outdoor exertion,” ACQI advises.

The Environment Protection Department Air Quality Health Index (AQHI), which has a different methodology, registered slightly lower readings, but still recorded Tung Chung in the ‘high’ zone for much of the weekend.

It warns of “moderate to very high” health risks this afternoon.

A government health warning issued Sunday afternoon explained:

However, the Hong Kong Observatory forecasts moderate east to northeasterly winds, “fresh tonight,” and bringing “one or two rain patches over the coast of Guangdong.”

But it adds that until then pollution levels will remain higher than normal.

At 2pm today Tung Chung’s air rated ‘unhealthy for sensitive groups’ on the ACQI chart.

 

Tung Chung bad air index hits ‘very high’ – more on the way

Tung Chung’s air quality readings again reached ‘very high’ yesterday, with more bad air forecast for later this week.

EPD air monitoring stations in Tung Chung recorded pollution in the ‘high’ and ‘very high’ levels for four hours late yesterday afternoon, peaking at 5pm.

The ozone reading was 162.7 micrograms, more than 50% above the World Health Organization standard of 100 micrograms per cubic meter. The concentration of fine particulates, PM2.5, reached 58.2 micrograms, 25 micrograms higher than the WHO standard.

The outlook for today is moderate, but the World Air Qualty Index website predicts further high levels this week, in particular Wednesday morning and early Saturday morning.

The high pollution levels across Hong Kong and much of Guangdong are the result of a northeast monsoon which is bringing dry sunny weather and light winds – ideal conditions for photochemical smog.

Under the EPD’s Air Quality Health Index (AQHI), a reading of 7 is high, 8-10 is very high, and above 10 is serious.

In ‘very high’ pollution conditions the EPD advises children, the elderly and those with heart or respiratory diseases to reduce outdoor exertion and stay indoors, especially those living in areas with heavy vehicle traffic.

Tung Chung air hits danger zone again

Tung Chung air quality once again has reached the most hazardous levels on the government air quality index.

From 4pm-7pm Wednesday, air quality reached 10 and 10+ on the EPD’s Air Quality Health Index (AQHI).

It remained at 10+, the highest level, for more than an hour. At that level the EPD urges people to restrict outdoor activity to the minimum and for children and the elderly to stay indoor.

The index reading for the district remained low this morning, but with a warning of possibly high health risk this afternoon.

It is the second time in 12 days that Tung Chung air has hit hazardous level, a combination of high temperatures and low winds.

The HK Observatory has issued another very hot weather warning today, predicting temperature could reach 35. The temperature at Chek Lap Kok at 10am was 32 degrees.