Nitrogen dioxide levels around some Hong Kong parks and schools ‘concerning’, Greenpeace survey finds, but scientists say results may not be as alarming as they look

Greenpeace study tested level of nitrogen dioxide, a pollutant released from vehicle exhausts and electricity generation, at 63 locations over two weeks

Findings came despite a 34 per cent fall in nitrogen oxide – a combination of nitric acid and nitrogen dioxide – emissions recorded between 2001 and 2017

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Greenpeace says nitrogen dioxide is a local issue that can be easily tackled by the government. Photo: EPA

Published: 8:30am, 22 Oct 2019Updated: 4:36pm, 22 Oct 2019

Concentrations of a major air pollutant can reach “concerning” levels around public parks and primary schools in Hong Kong, a survey by a green group has found.

But two scientists, who both endorsed the need to control the city’s roadside air pollutants, cautioned against the survey’s methodology, saying the findings might not be as alarming as they sound.

The Greenpeace air quality survey measured the level of nitrogen dioxide, a major pollutant released from vehicle exhausts and electricity generation, at 63 locations over two weeks.

The findings came despite a 34 per cent fall in nitrogen oxide – a combination of nitric acid and nitrogen dioxide – emissions recorded between 2001 and 2017. Such emissions were at their highest in 2003 at about 140,000 tonnes, dropping to less than 90,000 tonnes in 2017, official statistics show.

Greenpeace activists urge the government to tackle nitrogen dioxide emissions from traffic. Photo: Jonathan Wong

Shipping, electricity generation and road transport were the top three sources of Hong Kong’s nitrogen oxide emissions, accounting for 37, 27 and 20 per cent of the total respectively in 2017.