Pollution has returned to pre-Covid levels

Air pollution has rebounded now that life has returned to normal and borders have fully reopened, causing the annual average concentration of ozone to hit record highs, Clean Air Network said.

Every year, the network reviews data from the Environmental Protection Department's 18 air quality monitoring stations - 15 general stations and three roadside stations to gauge trends.

It said average concentrations of nitrogen dioxide, PM10 and PM2.5 hit historic lows in 2022 during Covid.

"Air pollution worsened in 2023, with average concentrations of most major pollutants increasing and getting close to 2019 levels," it said.

Compared with 2022, many of the pollutants saw double-digit percentage increases, with the largest being ozone concentrations at the three roadside stations - up by 32 percent.

The annual average concentration of ozone at general stations rose to 64 milligrams per cubic meter of air - up by 8 percent. Both readings are the highest levels ever recorded.

Only NO2 concentrations at roadside stations saw a slight decrease of 2 percent.

Western and northern parts, such as Tuen Mun, Yuen Long and North, have worse air quality, with Tuen Mun station particularly seeing the highest average concentrations of NO2, PM10 and PM2.5.

"Affected by a wide range of emission sources, such as road traffic, navigation, power plants and regional emissions, Tuen Mun has been one of the most polluted districts," it said.

Tap Mun station, which is away from urban sources of emissions, usually has the highest ozone concentrations, but it has been exceeded by Southern, the highest among all districts, last year.

"Apparently, zone pollution in urban areas has intensified, indicating this is no longer solely a regional problem," the network said, calling for local and regional solutions as soon as possible.

Ozone pollution is expected to deteriorate due to the rising number of electric vehicles, which has lower emissions of nitric oxide to scavenge ozone, while rising temperatures amid climate change has created favorable conditions for ozone formation.

It urged the government to expedite the transition to green transport, develop power facilities at cruise terminals, and to tighten the air quality objectives to meet WHO global air quality guidelines.