While police continue to dismantle the massive meth lab discovered at a Mississauga industrial complex earlier this week, dozens of business owners are frustrated by the pace of the cleanup.

The owners have not been allowed back into their workplaces on Sismet Drive, near Pearson airport, which they say has cost them thousands of dollars in lost revenue.

"About five to six grand a day," said Terrance Parakh, who can't get into his unit for supplies to run his pipe business.

"I know it's not safe, but this should have been done by now -- today's Saturday. I heard they would be working all night, but I don't think so."

"If it continues like this for another week or two, it's kind of hard for me to survive, because there are expenses every day and I can't make any money," said Rui Ariosa of Skyway Trucking.

Officers from Peel and Toronto raided the clandestine methamphetamine lab on Tuesday night, calling it one of the largest drug operations of its kind in the GTA.

Investigators seized an "enormous amount" of ecstasy pills, several pill presses, 80 drums of chemicals and two drug kitchens inside three units at the warehouse.

Chemists were brought in to try to neutralize active reactions between the dangerous chemicals as officers took apart the sophisticated drug lab.

Police say they understand the frustrations expressed by the business owners, but say safety is their top priority. The lead investigator told CTV Toronto there are still dangerous vapours in the air, and the scene won't be cleared until the air quality is deemed safe.

Police hope to reopen the complex on Monday morning.

Investigators say the lab had probably been operating for a year. Four people have been charged in the case.

With a report from CTV Toronto's John Musselman