Online clothes store Pretty Little Thing has faced calls from workers to shut its warehouse, described by one as "a breeding ground for Covid-19".
The retailer's site in Sheffield remains open after the government called on people to stay at home.
Workers said there was a shortage of hand sanitiser and it was "impossible" to keep a safe distance from others.
Pretty Little Thing said it had "implemented stringent hygiene and self-distancing measures".
One worker, who asked to be identified only as Patrick, said: "Going to work has the chance of killing me and infecting my grandson. To save lives, shut the place."
Patrick said the warehouse, in the Tinsley area, had 4ft wide aisles where up to 10 people worked at a time, often passing close by one another while picking clothes for dispatch.
Another warehouse worker, who did not to want to be named, told the BBC: "There are four small sanitiser dispensers in the warehouse and they're always empty, it's a breeding ground for Covid-19.
"The work we do is not essential, who wants to buy clothes not knowing when you will be able to wear them?"
On Monday, the prime minister outlined new measures telling people they should only go to work "where this is absolutely necessary and cannot be done from home", with shops selling "non-essential goods," including clothes, told to close immediately.
However, Health Secretary Matt Hancock later said those who cannot work from home should go to work "to keep the country running".
Bill Adams from the Trades Union Congress (TUC) said there had been mixed messages from the government.
He said workers who felt they were being asked to take "unnecessary risks" should seek immediate advice from a union or get together to "tell the bosses that what they're doing is unsafe".
In a statement, Pretty Little Thing said: "We have transitioned the majority of our teams to working from home, where it is not possible for our teams to do their jobs from home we have implemented stringent hygiene and self-distancing measures and have lots of support in place for them whilst we find a suitable alternative.
"Like every other business in the country, we are working around the clock to keep pace with government guidance and do the very best for our people both socially and financially and to keep them safe and well."