Now authorities have been urged to come up with measures to lessen the health impact.

Sukanda Padpadee, an expert from the Department of Health’s Health Impact Assessment Division, presented her study on exposure to air pollution from the plant during the Public Health Ministry’s annual academic conference last month.

Thanks to encouragement from the National Energy Policy Council, the number of biomass power plants had risen, as have the complaints about the impact of these plants, she said. It was now necessary to study the air pollution and health risks, so related agencies can make better preparations in handling long-term impacts.

The study monitored four biomass-based power plants – two with capacity below 10 megawatts and two with greater capacity – which were not near any other establishments that could pollute the air. The collected data at four air-quality stations was then compared against one controlled air-quality station.

The four stations were Wat Nikhomkhet and the 16th house in Tambon Tani for the smaller capacity plants; and the Ban Rattana School and Ban Samet School for the larger plants.

It was found that the amount of dust in the air stood at 0.047-0.188 milligrams per cubic metre. The amount of dust particles less than 10 microns in diameter (PM10) was at 14-117 milligrams per cubic metre and the amount of dust particles less than 2.5 microns in diameter (PM2.5) was at 10-99 milligrams per cubic metre, she said.

The overall dust in the air at Wat Nikhomkhet and Ban Rattana School was higher than at the control station, while the amount of PM10 and PM2.5 at the two places plus Ban Samet School was significantly higher than the control area, she said.

The air quality at Wat Nikhomkhet, the 16th house and Ban Samet School were lower than the WHO standard, she said, adding that the 16th house had the highest risk of exposure to PM10 and PM2.5 dust, which was deemed unacceptable.

She said the study concluded that biomass power plants do yield tiny dust particles that go beyond WHO-recommended levels, so measures should be put in place to monitor the health impacts on nearby residents.