Broken, 'friable' asbestos has been found at two southern Illawarra primary schools - Barrack Heights and Oak Flats public schools - and at Bulli, Corrimal, Keira and Lake Illawarra high schools.

An additional 33 schools from Helensburgh to Kiama contain 'damaged asbestos' according to the education department's Schools Asbestos Register.

Labor's Courtney Houssos raised concerns about the management of asbestos in schools in NSW Parliament this week.

She told Wednesday's Budget estimates hearing that 109 schools in NSW had the "worst category of asbestos, which is known as friable asbestos".

"It is literally decaying and the fibres are breaking down," she said.

Ms Houssos said a further 998 schools across the state had 'damaged asbestos' that was breaking down according to the department's own data, from November 2017.

"According to NSW Health, they say that broken and damaged asbestos can become loose and airborne which poses serious health risks," she said.

"...This is not asbestos that is sealed up in the walls. This is asbestos that is breaking down, that is underneath classrooms, that is debris, that is potentially fraying in school toilets, in staff toilets, in school libraries and halls around the state."

Department of Education secretary Mark Scott said the department had a rigorous system of maintenance and monitoring at all NSW schools.

"We have 800,000 children in NSW schools," he told the hearing. "Their parents send them off to those schools. We have an absolute commitment to creating a safe and healthy environment for those students.

"Of course, there has been concern about asbestos in the community. But I think it is important that we reassure parents that we have strong processes underway to identify where there are issues and to manage any issues with asbestos."

In a statement, Mr Scott said asbestos was commonly used in many buildings between the late 1940s and late 1980s, and was present today in materials such as cement sheeting and roofing, vinyl floor tiles and wall lining.

"At any time friable asbestos is suspected, the department acts immediately to secure and remediate," he said.

"This includes the removal of students from the area of concern, the engagement of an independent hygienist, air monitoring and the commissioning of licensed contractors to remove the asbestos in accordance with the Safe Work NSW guidelines."

The state education department's Schools Asbestos Register, available publicly, contains information about the existence and location of asbestos-containing materials on school sites.

The vast majority of materials containing asbestos are safe, according to the department, with studies showing that if they are left undisturbed and are in sound condition they pose no risk to health.

According to the site, Barrack Heights and Oak Flats public schools and Bulli, Corrimal, Keira and Lake Illawarra high schools have been found to gave 'friable' asbestos.

The site states friable asbestos is "any material that contains asbestos and is in a powder form or can be crumbled, pulverised or reduced to powder by hand pressure when dry".

At the six local schools it was mainly found in ceiling materials in areas such as toilet blocks and stairwells.

Over 30 schools were also found to have 'damaged' asbestos. These included Albion Park, Albion Park Rail, Berkeley West, Coledale, Coniston, Corrimal, Fairy Meadow, Figtree, Gwynneville and Helensburgh public schools.

Also listed were Lake Illawarra South, Minnamurra, Mount Brown, Mount Ousley, Mount Pleasant, Mount St Thomas, Peterborough, Pleasant Heights and Scarborough public schools.

Stanwell Park, Towradgi, Tullimbar, Warilla, Warrawong, Wollongong and Woonona public schools also showed evidence of damaged asbestos.

High schools listed included Figtree, Kiama, Oak Flats, Smith's Hill, Warilla and Wollongong high schools and Five Islands Secondary College.

Parents and students can also view their school's asbestos register by contacting their school principal.