Benita Mehra quit after being linked to the charitable arm of a firm which supplied the block's cladding.
The recruit got into difficulty during a training exercise on Tuesday.
A total of 31 tests have concluded and there are no confirmed cases in Britain, government says.
The star says she has been "plagued" by injuries since the start of her tour and has been told to rest.
The naturalist speaks at a newly-formed citizens' assembly examining how the UK cuts emissions.