A gas leak at Hong Kong Polytechnic University led firemen to a cache of 100 litres of inflammable liquid yesterday.
Five air-conditioning technicians inhaled the unknown gas and became ill while working on the ground-floor plant of the university's Block G in Hunghom.
Firemen searched the building and found the gas was coming from a solution used to paint the floor of an office in the same block.
A spokesman for the Fire Services Department said: 'We suspected the gas emitted from the solvent was pumped into the ground-floor plant through the ventilation system.' A drum containing the solvent was found abandoned in the office with its cover open. Samples were sent to a government laboratory for examination and the drum was taken to a dangerous goods godown.
Four of the workers remained in satisfactory or stable condition last night. One 55-year-old man was discharged after treatment.