Tate stops visitors trampling on Sunflower Seeds

Tate Modern is to stop visitors walking over the Chinese artist Ai Weiwei's vast field of 100m porcelain sunflower seeds because of health and safety fears over ceramic dust.

As revealed by the Guardian, the Turbine Hall installation has been closed since yesterday morning because of worries that dust inhalation might be a health risk. That means the thousands of visitors who traipsed through the installation between Monday and Wednesday were the lucky ones. The work will now be viewed from the building's bridge.

"The Unilever Series, Sunflower Seeds, by Ai Weiwei is made up of over 100m individually handmade porcelain replicas of seeds," the Tate said today.

"Although porcelain is very robust, the enthusiastic interaction of visitors has resulted in a greater than expected level of dust in the Turbine Hall. Tate has been advised that this dust could be damaging to health following repeated inhalation over a long period of time. In consequence, Tate, in consultation with the artist, has decided not to allow visitors to walk across the sculpture."

The work is intended to be interactive and to have people walking through it, although some visitors, mainly children, had more fun in the seeds than curators might have liked.

The work was closed yesterday for reasons which a spokeswoman initially said were artistic: the work simply needed putting back into shape. The Tate revised that statement this morning.

One visitor, who preferred not to be named, said she arrived at the gallery to see the work in mid-afternoon yesterday and waited 45 minutes before giving up. "It was very frustrating – there was no sign up about it, nobody to ask what was going on. There were two men raking it incredibly slowly. When I found someone to ask they said it was because of the dust it was creating and there was a meeting going on about it upstairs."

The Chinese artist's work, consisting of 100m hand-painted replica sunflower seeds, has proved popular since it opened on Monday.

Until yesterday the biggest issue surrounding the work had been whether visitors could take home one of the 100m seeds, all hand-crafted in China's porcelain capital, Jingdezhen. The official Tate line was certainly not, but the instruction was not always heeded.

Tate Modern has had health and safety problems with art in the Turbine Hall before. People hurtling down Carsten Höller's slides caused some nervousness in 2006, and a year later signs urged visitors to be careful viewing Doris Salcedo's 167m crack in the floor.