Danger: artist at work

It smells, it rots, it leaks. Contemporary art is fast becoming a health hazard.

The "hazardists" are taking their place among art movements of the 20th century, with hazardism evident at most of the major galleries.

As installation artists use dead animals and poisonous gases, so visitors to exhibitions are having to ask themselves not only "Is it art?", but "Is it safe?"

At the weekend, more than 100 visitors and staff were evacuated from the Tate Gallery's Rites Of Passage exhibition after iodine gas leaked from a sculpture by Hamad Butt.

Prior to that, a gallery in New York banned an installation piece by the British artist Damien Hirst, shortlisted for the Turner Prize, for fear of an outbreak of vomiting among visitors. The exhibit was a rotting sculpture of a cow and bull. A hydraulic device was inserted into the two animals in a glass tank to simulate them copulating as they rotted away.

The New York health department said that posed a public health risk, as it might explode or provoke vomiting among spectators. The vomiting was anticipated not so much as an aesthetic judgement. Rather, officials said that if the tank was sealed it could shatter from the build-up of methane from the carcass; if there was an outlet for the gases the noxious odours would overwhelm visitors.

Hirst, who acquires some of the raw material for his art from an abbatoir in Guildford, is probably the pioneer of art as a health hazard. When Mother And Child, a cow and calf in formaldehyde, was exhibited at the Venice Biennale, it sprang a leak, causing the organisers to clear the gallery while they summoned public health officials.

Hirst is now working with engineers to create an air-cleaning filter system for the cow and bull.

A spokesman for the artist articulated the problems of the modern installation conceptualist: "There are particular particles that could make humans sick and release an overwhelming smell in the gallery, and we've been working to overcome that."

Hirst and Hamad Butt are not alone. At the Ikon Gallery in Birmingham, visitors kept a wary eye on the ceiling when Carlos Capelan slapped mud from a riverbank on the ceiling and walls. He said this represented the "dark and humid female side of things".

Rebecca Horn, who suspended a piano upside down from the Tate Gallery ceiling, is the high priestess of hazardism. When she exhibited her sculpture Kiss Of The Rhinoceros at the Serpentine Gallery in London, a sign next to it warned visitors to keep their distance because of high voltage. The sculpture consisted of two metal arms each of which ended in a rhinoceros horn. The arms swung and met and sparks flew.

Hazardism can be dangerous not just to the spectator, but to those who install the artwork. The American artist Christo, who wrapped the Reichstag in a white fabric, employed only skilled steeplejacks for the job.

Sandy Nairne, deputy director of the Tate Gallery, said: "We have three sculptures at present that contain noxious gases. But we talk with safety authorities all the time and do these things very carefully."

Installations can endanger the artist as well. When Hirst exhibited a dead sheep in a tank of formaldehyde last year, a spectator threw in black dye and changed its colour. Interactive hazardism was born.

nThe Government has deferred an export licence for an 18th century painting sold for pounds 4.5m. Museums or institutions now have six weeks to find the money to buy La Lecture de Moliere, by Jean-Francois de Troy.