Air pollution is no longer invisible, thanks to the technology that is able to measure concentration of air pollutants (Fine Particulate Matter, PM2.5) by a mobile monitor which is light in weight and easy to operate.

By measuring pollutants near their homes and schools, members of general public discover first-hand the levels of air pollution of the neighborhoods that affect them daily. The data then collected can be shared with the public online.

Brief introduction

Hong Kong has a network of 16 monitoring stations – comprising of 13 general monitoring stations, and only 3 roadside monitoring stations.

However, the air pollution figures does not accurately reflect the air quality we breathe.

Previous studies by Clean Air Network have shown significant differences between data collected at government General Monitoring Stations located 11-25 meters above ground and air quality monitors positioned at street level, with readings in excess of thirty five percent at street level compared to the above ground monitors, during the same monitoring period.

As such, there is a need for Community Monitoring that provides a more accurate picture of the levels of pollution pedestrians face every day.



CAN has been running this air quality monitoring program with schools and communities around Hong Kong. We provide educational materials on air pollution and invite the public to create their own monitoring plans. We then teach them to use our air quality monitors to measure air pollution at various locations around their neighbourhood. By physically measuring pollutants near their homes and schools, people discover first-hand the levels of air pollution that affect them daily. The data then collected is shared with the public through our social media.

Why PM2.5?

PM2.5 is the most lethal component of air pollution, small enough (1/30th of a hair in width) to travel into our lungs and bloodstream and cause major health problems. In Hong Kong, our PM2.5 level is three times above WHO recommended guidelines.

The spatial variation of PM2.5 levels can be significant and the current government monitoring network has only 13 general stations and 3 on roadside; thus not enough to reflect PM2.5 pollution on a local level and in particular, various black spots.

We believe a more localized and EXTENSIVE PM2.5 monitoring network in Hong Kong is the best way to engage the public, raise awareness, facilitate policy changes and protect public health.


The first objective of this project will be to extend Clean Air Network’s existing monitoring network into districts in Hong Kong that have no roadside monitoring stations, in order to better understand pollutant levels there and the main factors contributing to air pollution in those areas.

The collected data can also be used towards engaging residents and raising their awareness of pollutant levels in their own neighbourhood – and this is the project’s second objective. Though acknowledgement that Hong Kong’s air pollution’s is more or less ubiquitous is common, most citizens do not have a strong grasp of air pollution’s health impacts or understand the safe health thresholds for pollutants, such as fine particulate matter (PM2.5).

PM2.5 is considered to be one of the most dangerous pollutants due to its small size, which allows it to pass through cell membranes and lodge deep into organs, including the lungs, heart and even the brain. Resulting health effects can include an increased risk of asthma attacks, an increased risk of lung cancer mortality, an increased risk of heart attack and even cognitive decline.

Hong Kong’s level of PM2.5 is the eighth worst out of 565 cities worldwide, evident from the haze that often blankets the city. This loss of visibility has been directly linked to higher mortality rates. A study conducted by the University of Hong Kong’s School of Public Health showed that for every loss of 6.5 kilometers of visibility, there is a 1.13 per cent increase in all natural causes of death, accounting for about 450 deaths per year. These statistics demonstrate the grave threat to public health posed by PM2.5 and, subsequently, the need for citizens to understand the situation so that they can take steps to protect themselves.

In addition to building this understanding of air pollution’s health impacts, another project objective is to grow awareness and support for air pollution control measures. While personal empowerment is crucial in tackling an issue as pervasive as air pollution, it is also important that citizens have knowledge of the steps the government is taking to protect public health so that comprehensive, society-wide measures can be taken.

The fourth objective of this project is to aid in the coordination/creation’ of air quality policy in Hong Kong to maximize the public health benefits of reduced emissions to Hong Kong’s residents. Both the public and the government must be made aware of the on-the-ground situation, with regards to PM2.5, to ensure that effective air quality control measures can be put into effect. District-level planning such as bus rerouting, pedestrian zones can be formulated based on the data collected.


Story posted on
10th Jan, 2017


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