A giant lifelike foggy sunset created at the Tate Modern art gallery has led to complaints from staff who say it is making them feel ill.
About 200 sodium lights help create the effect of a sunset
The installation, created from sugar and water by Danish-born artist Olafur Eliasson, fills the vast Turbine Hall at the London institution.
A "small number" of attendants have complained that the concoction has made them unwell.
The gallery said the mixture was harmless but it was investigating.
In a statement, the museum said it prided itself on the highest health and safety standards and providing the best possible environment for visitors and staff.
It said it had consulted extensively with experts before allowing the artwork to be installed.
"The haze is composed only of sugar and water and is used safely in nightclubs throughout the world," a spokesman said.
He said the museum's five levels above the Turbine Hall were not affected because of its environmental control system.
Eliasson's work, which will be in place for five months, is based on the British obsession with the weather.
He put 300 mirrors on the ceiling, and placed more than 200 lamps behind a semi-circular screen.
The "sun" appears whole because of the reflection, bathed in an eerie fog of frozen water vapour.