08/25/2016 13:27 EDT | Updated 08/26/2017 01:12 EDT

Most of remaining Fort McMurray evacuees allowed to go home

EDMONTON — Alberta's top health officer is approving the return of some of the last evacuees from the Fort McMurray wildfire.

But Karen Grimsrud says about one-third of the homes in two of the most badly damaged neighbourhoods remain too unsafe to re-enter.

Grimsrud has given the go-ahead to open 439 houses in the two districts after ensuring the municipality removed enough toxic ash and debris.

The material was found to be contaminated with heavy metals such as lead.

She says no further testing of the resettled residential areas is planned, but public areas such as parks and pathways will be examined.

She gave no date for when the 242 homes still too contaminated to inhabit will receive the go-ahead.