Hong Kong’s Air Quality and Its Relation to Temperature

Hong Kong’s air quality was under 3 in its Air Quality Health Index (ADHI)’s scale, with a low-banded health risk followed by stable levels in PM2.5 and PM10.

The ADHI was reported on the scale from 1 to 10 and 10+, and are grouped into five health risk categories involving low, moderate, high, very high and serious with specific health advice provided.

According to Hong Kong’s Environmental Protection Department, “no action is required” among general public, involving people who are working outdoors and sensitive to air pollution.

However, Sai Kung and Kowloon districts had the relatively high value of numbers in both PM2.5 and PM10, with the darker shade of parts can be seen from the maps. Air in both areas were more polluted compared with other districts in the city.

Hong Kong Current Air Quality PM2.5

Current Air Quality PM2.5 of Sai Kung and Kowloon districts

Hong Kong Current Air Quality PM10

Current Air Quality PM10 of Sai Kung and Kowloon districts

National Pollutant Inventory defines PM10 as particulate matter 10 micrometers or less in diameter, while PM2.5 refers to particulate matter 2.5 micrometers or less in diameter.

Sources of PM 10 includes crushing or grinding operations and dust stirred up by vehicles on roads, while sources of PM2.5 are produced from all types of burning within motor vehicles, power plants, forest fires and other industrial activities.

Compared to PM10 which particles could be stopped from lungs, PM2.5 can pass into human’s blood supply and be carried throughout our bodies. PM2.5 can cause more severe consequences to our health, including lung cancers and cardiovascular disease.

Reasons of why Sai Kung and Kowloon had particularly worse air quality can vary. Research shows that Kwun Tong, which belongs to Sai Kung district, is now planning for developing new bus routes and building apartments.

Major pollutants in the area, such as nitrogen dioxide and PM10, may come from construction projects and vehicle exhaust. Increasing population of residents moving into new housing estates can also contribute to the same factor.

In Kowloon district, ferries seem to be the major concern, where they produce most of the harmful sulphur dioxide, nitrous oxides and PM2.5 that we breathe every day.

According to the Environmental Protection Department, in 2016, there were 8,540 tonnes of sulphur dioxide, 32,900 tonnes of nitrogen oxide and 1,480 tonnes of PM2.5 pollution produced through shipping.

Meanwhile, smog and haze entering Hong Kong from mainland China on the north and east winds can also result in poor quality air.

From the map below, Kowloon, Yuen Long and Kwai Tsing districts were in slightly higher degrees of temperature.

Hong Kong Current Temperatures

Current Temperatures of Kowloon, Yuen Long and Kwai Tsing districts

The weather and local climate can also affect air quality. When weather is hot, amount of pollutants involving PM2.5 and PM10 tends to increase.

Furthermore, higher temperatures speed up chemical reactions of pollutants in air, resulting in more smog and pollution produced.

Based on the relationship between temperature and amount of pollutants in air, it may provide another angle to interpret why Kowloon district has a higher value of number in PM2.5 and PM10.