BANGKOK, Feb. 2 (Xinhua) -- Bangkok's air pollution eased slightly on Saturday, with the level of toxic dust reducing in most areas but the health threat posed by PM 2.5 still lingering.

The reading of particulate matter 2.5 micrometers ranged from 31 to 60 micrograms per cubic meter during the past 24 hours, according to the pollution control department on Friday.

The PM 2.5 fell by 18 micrograms per cubic meter of air on average while dangerous levels of PM 2.5 dust were reported at five air-quality monitoring stations, above safe level set at 50 micrograms.

Bangkok's air quality index was around 151 on Saturday, making it "unhealthy."

Thai Prime Minister Prayut Chan-o-cha on Friday asked owners of diesel powered private cars to avoid using their vehicles, except when absolutely necessary, until the smog situation in and around Bangkok has eased significantly.

According to pollution control department, the combustion of bad diesel engines has contributed most to the surge in dust levels.

State weather forecasters said the lack of wind and higher air pressure has aggravated the situation, which is likely to persist at current unhealthy levels at least until next Monday.

The government has tried seeding rain clouds, reducing traffic, and hosing down streets to curb the hazardous smog.

Those celebrating the Lunar New Year holidays next week were asked not to burn incense or light fireworks.

Companies in Bangkok allowed workers, especially those sick or pregnant, to work from home to avoid exposure to toxic PM 2.5 dust.