Hong Kong Air Pollutant Emission Inventory
The Environmental Protection Department (EPD) compiles the Hong Kong Air Pollutant Emission Inventory annually to analyze the quantity of local air pollutant emissions and their major emission sources for supporting the formulation of effective air quality management strategies in Hong Kong. It also provides necessary data for carrying out air quality impact assessments. The emission inventory for Hong Kong was first published on EPD's website in March 2000.
The emission inventory comprises estimates of emissions from seven source categories for six major air pollutants, namely: sulphur dioxide (SO2), nitrogen oxides (NOx), respirable suspended particulates (RSP or PM10), fine suspended particulates (FSP or PM2.5), volatile organic compounds (VOC) and carbon monoxide (CO). The emission sources include public electricity generation, road transport, navigation, civil aviation, other combustion sources, non-combustion sources, and hill fires.
Other combustion sources are defined as sources involving combustion, other than public electricity generation, road transport, navigation and civil aviation. Major contributing sources in this sector include non-road mobile machineries operating in construction sites and container terminals.
Non-combustion sources are defined as those remaining sources that do not involve combustion, from which only VOC, RSP and FSP emissions are significant. In this category, the major emission sources for VOC include paints and associated solvents, consumer products and printing, whereas those for RSP and FSP include paved road dust, cooking fumes, construction dust and quarry production.
In Hong Kong, hill fires are one of the sources of particulates. As most of the hill fires in Hong Kong are caused by human negligence or accidents and are sporadic in nature, their emissions cannot be reduced through emission control measures like other pollution sources. In order to enable more meaningful comparison on the emission trends of controllable pollution sources and the effectiveness of local emission control measures, hill fires are reported separately in Sectoral Analysis.
Overview of 2021 Emission Inventory
In 2021 the total emissions of the major air pollutants in Hong Kong were 4 760 tonnes of SO2, 53 620 tonnes of NOx, 2 820 tonnes of PM10, 2 170 tonnes of PM2.5, 21 950 tonnes of VOC and 57 400 tonnes of CO, respectively. As the local activities in 2021 were still affected by COVID-19, the total emissions were by and large at the similar level as 2020.
Emissions of five major air pollutants, including SO2, NOx, PM10, PM2.5 and CO, decreased slightly by 1% to 5% in 2021 as compared to 2020. VOC, the remaining major air pollutant, showed little variation between 2020 and 2021. Navigation was the major emission sector in Hong Kong in 2021. With the significant reduction in emissions from the other sectors over the past years, "Brake, Tyre & Road Surface Wear" of the non-combustion sources has become the major emission source of PM10 in Hong Kong. Non-combustion VOC emissions have remained steady over the three years from 2019 to 2021 and are expected to be affected by the increase in construction activities in the coming years.
2021 Emission Inventory
The diagram below shows the emission inventory for 2021 under different emission sectors including public electricity generation, road transport, navigation, civil aviation, other combustion sources and non-combustion sources.
Emission Inventory Report
2021 Hong Kong Air Pollutant Emission Inventory Report
Useful References
Intergovernmental Panel on Climate Change (IPCC)
U.S. Environmental Protection Agency (U.S. EPA - AP42)
European Environment Agency (EEA - EMEP/EEA Emission Inventory Guidebook)
Census and Statistics Department (C&SD - Hong Kong Statistics)
Electrical and Mechanical Services Department (EMSD - Hong Kong Energy End-use Data)