Lidl in Wembley Park is under investigation after contractors allegedly let toxic cleaning chemicals waft around its bakery section in mid-afternoon in front of coughing customers.
Shopper Nitin Parshotan took himself to A&E with a headache, nausea and sore throat hours after witnessing unprotected operatives spraying the ovens in the Wembley Park store on October 1.
The dad-of-one was in the store at about 3.45pm when he approached the bakery section and along with other customers began coughing.
He said: "They were cleaning the ovens at 4pm, at a time when children dive into the bakery. I and all the customers were coughing. It was horrifying.
"I asked a manager to close the aisle but he stared at me blankly, like I was a martian or something. Eventually they did close the oven doors."
He took photos of the chemical containers which were placed in trolleys. The Zenith Liquid Degreaser used suggests on its label to wear protective gloves and eye googles when using it but operatives were wearing neither, said Mr Parshotan.
When he reached home he called Lidl's customer services who allegedly told him the operatives were due to come at 10pm but had arrived six hours early and been allowed to start work. "Over the phone they confirmed it all to me and Lidl say all calls are recorded," he added.
"I had to go to A&E for treatment afterwards as the headache, nausea and sore throat just got worse. They kept me under observation for a few hours.
"I've raised the issue as a public health concern."
Brent Council is now investigating. Cllr Tom Miller, lead member for community safety and engagement, said: "We take all reports of safety breaches very seriously. Our Health and Safety Inspector visited the site the following day to speak with the store's management, establish which cleaning products were being used and gather their safety data records.
"We have also asked for a copy of the complainant's medical report, as this may provide important independent evidence of the symptoms suffered and help inform what action we are able to take as a result."
A council spokesperson added: "The nature and severity of the claimant's injury is important for us to assess in order to determine the future course of our investigation."
Lidl did not respond to requests for comment.
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