MANILA, April 28 -- The Department of Environment and Natural Resources (DENR) said the hazy skies that greeted residents in the National Capital Region (NCR) on Monday may be caused by two separate fire incidents in Quezon City and in neighboring Rizal province.

These are the fires that broke out at a sanitary landfill in Montalban town and at a warehouse along Commonwealth Avenue in Quezon City, the agency's Environmental Management Bureau (EMB) said in a statement.

Real-time air quality monitoring conducted by the DENR-EMB showed that concentrations of particulate matter, specifically PM10 and PM2.5, peaked between 5 a.m. and 7 a.m.

However, the EMB said readings normalized and returned within the guideline values by around 9 a.m. ...