Asbestos has become an issue as workers tear down the old General Motors plant on Boxwood Road.
The plant was shut down in 2009 and will be replaced by a distribution center.
But union officials have thrown up picket line charging that when the structure’s skeleton is finally torn down dust will drift beyond the property itself.
And the union says it has video taken by a member who went undercover to show what is being done.
The site has been the focus of the union and local activists concerned about the asbestos.