Clean Air Network (CAN) analyzed the air quality data in 2021 from the Environmental Protection Department and concluded that air pollution in Hong Kong worsened, compared to the previous year, as social distancing measures had been relaxed in most time of the year. Public health was therefore at risk – it is estimated that air pollution in 2021 resulted in 1,329 premature deaths and a total economic loss of 15.8 billion Hong Kong dollars.

World Health Organization (WHO) tightened its air quality guidelines in 2021, lowering the recommended levels of air pollutants. The concentrations of major air pollutants in Hong Kong in 2021 immensely exceeded the new WHO standards – the most serious being roadside NO2 concentrations, exceeding by 620%, while roadside PM2.5 concentrations exceeded by 320%. CAN urges the government to accelerate the implementation of zero emission public transportation to improve roadside air quality.


Rising Levels of Major Pollutants Increased Social Costs

The annual average concentration of major pollutants, including nitrogen dioxide (NO2), respirable suspended particulates (PM10), fine suspended particulates (PM2.5), and ozone (O3), all increased in 2021, compared to 2020 (see Table 1).

As the COVID-19 pandemic broke out in 2020, transportation was reduced because of social distancing measures such as suspension of classes and remote working, resulting in a drop in the level of air pollution. In 2021, as those measures were relaxed, the level of air pollution bounced back, though yet to reach that in 2019 before the pandemic. However, if the government does not take immediate action to curb such rising trend, public health will be under threat.

Table 1: Annual Average Concentration of Major Air Pollutants (μg/m3)

2021年空氣質素回顧:污染水平回升 遠超世衛新標準 路邊NO2超標逾六倍 e01

The School of Public Health of the University of Hong Kong estimated that in 2021 the adverse health impact brought by air pollution had led to 1,691,209 doctor visits, 98,451 hospital bed days, and 1,329 premature deaths. A total economic loss of 15.8 billion HKD had also been inflicted.

Table 2: Health and Economic Costs of Air Pollution

2021年空氣質素回顧:污染水平回升 遠超世衛新標準 路邊NO2超標逾六倍 e02

(Source: Hedley Environmental Index, School of Public Health of the University of Hong Kong)


Roadside NO2 Surpassing WHO Standards by 620%

WHO tightened its air quality guidelines (AQGs) in 2021. The levels of annual average concentration of major pollutants exceeded WHO AQGs. The greatest difference was recorded in the level of roadside NO2, which exceeded by 620%. Roadside PM2.5 also exceeded by 320%.

Table 3: Comparison between Annual Average Concentration of Air Pollutants and WHO AQGs

2021年空氣質素回顧:污染水平回升 遠超世衛新標準 路邊NO2超標逾六倍 e03

Policy Recommendations

CAN suggests the government to take the following actions to improve air quality in Hong Kong:

  1. Accelerate Full-scale Adoption of Zero Emission Mobility
  2. Implement Actions Stated in “Clean Air Plan for Hong Kong 2035
  3. Tighten AQOs to Meet WHO Standards
  4. AQOs Review should be Open and Transparent
  5. Make Solid Plans to Reduce Ozone Levels

For detailed analysis and policy recommendations, please refer to the press release:

Story posted on
18th Jan, 2022


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