Switching on the fan at home is not advisable during hazy conditions because it stirs up indoor particles, and well-ventilated classrooms are safer for children than the outdoors even if they lack air-conditioning.

These were among the answers three experts gave to Straits Times online readers on Monday in a specially organised forum on Facebook. Health-related questions in particular dominated the one-hour forum on The Straits Times Facebook page, reflecting people's anxiety about the haze's long-term health impact.

Dr Ong Kian Chung, a respiratory medicine specialist at Mount Elizabeth Medical Centre, responding to a question by a reader on how to get rid toxic particles that we may have inhaled, said that there was no scientifically proven way of purging small, toxic particles called PM2.5 from the human body.

The best way to limit their impact is to wear face masks outdoor during the haze. The National Environment Agency also has a list of recommended indoor air purifiers on its website, he said.

The other two experts were Dr Santo Salinas, a senior research scientist at the Centre for Remote Imaging, Sensing and Processing at the National University of Singapore; and Dr Erik Velasco, a research scientist at the Centre for Environmental Sensing and Modelling, part of the Singapore-MIT Alliance for Research and Technology.

Dr Velasco said that people should ensure their protective masks fit snugly over their faces, and that even stubble could reduce the masks' effectiveness as particles could slip into gaps caused by the facial hair.

More answers from the panel on the haze can be found at: http://on.fb.me/17xYmIZ