The Environmental Protection Department expects the general and roadside Air Pollution Indices to remain higher than normal over the weekend.

The department recorded very high API of 116, 125 and 101 at the Tung Chung, Yuen Long and Central-Western reading stations at 8am today due to respiratory suspended particulate concentrations. All roadside stations exceeded the 100 API mark, with Central at 145 due to nitrogen dioxide.

The department said the city was affected by a continental airstream with relatively high regional background air pollution. The wind was weak and prevailed from the north. The very high API readings were a result of the trapping of local pollution under the light wind coupled with the influence of regional air pollution.

It expects the regional background air pollution will continue to be high and air dispersion will remain poor tomorrow. The general and roadside API readings will therefore remain at higher than normal levels.

People can check the latest hourly API readings for different locations on 2827 8541 or on the department's website.