Friable asbestos has been discovered at one of five more contaminated Sydney sites as the investigation into tainted mulch distributed across NSW continues.

The NSW Environmental Protection Authority on Friday said friable asbestos had been confirmed at Wood St in Forest Lodge, in Sydney's inner west.

Friable asbestos can be reduced to powder by hand and may cause serious health problems if inhaled. It is more dangerous than bonded asbestos.

The latter has been found at the other four contaminated sites: Harold Park at Forest Lodge, Wentworth Park at Glebe, a Glenmore Park construction site and Cranebrook High School.

All sites have been fenced off to protect the public.

This brings the number of locations found to have asbestos-contaminated mulch to 59.

The EPA investigation began after bonded asbestos was detected in recycled mulch at the inner-city Rozelle Parklands in January.

The agency has been tracing and testing other locations where the suppliers of the tainted mulch deposited the material.

The EPA also said further testing at an Aldi supermarket at Cobbity in Sydney's southwest had confirmed friable asbestos.

Bonded asbestos had previously been confirmed at the site.

Six health facilities will have cordons removed from their gardens after testing negative for asbestos.