Manila, Sept. 7 -- Sensitive groups are urged to take precautions as continuous ambient monitoring stations have reported "unhealthy for sensitive groups" air quality levels since Aug. 30, the Department of Environment and Natural Resources-Davao Region (DENR-11) said Monday.

Miralou Blanco, chief of DENR-11's environmental monitoring and enforcement division, said in a press briefing that the Calinan station first recorded the unhealthy levels on Aug. 30, followed by similar readings in Digos City on Sept. 4.

Malita town in Davao Occidental also detected changes in air quality concentration attributed to haze.

Blanco explained that the stations, which measure air quality 24/7, showed elevated levels of particulate matter 2.5 (PM2.5), ...