The old Batlow hospital was one building which burnt to the ground known to contain asbestos, and Stephen Beanman of the Environment Protection Authority warned residents to avoid such areas.

"If asbestos is suspected or identified, the site may be sprayed with a non-toxic, coloured PVA glue, to give a temporary seal to reduce the risk of airborne asbestos fibres," the executive director of hazardous incidents and environmental health said.

Asbestos was not the only potential hazard in a fire zone, according to Mr Beanman.

"Houses, sheds and other buildings that have been burnt in a bushfire can leave potential health and safety hazards in the remaining rubble and ash," he said.

"Hazardous household materials that may be present after a bushfire include asbestos, chemicals (including household, cleaning, garden and farm chemicals), ash and dust (including ash from burnt treated timbers) solar panels and damaged gas bottles.

"Other hazards may include unsafe building structures, unsafe trees, electrical hazards and damaged or missing pool fencing."

Mr Beanman said it was important not to enter a property until being advised it is safe to do so by emergency services, utility companies and local councils.

"If your home or buildings have been damaged in the fires, an assessment is undertaken by NSW government agencies for the protection of you, your family and neighbours," he said.

"The assessment must be completed before you can safely return to your property."

The EPA outlined a list of aspects to consider and precautions to take when reentering a bushfire affected property: