Explosion in Melbourne paint laboratory

Two people are being treated for nausea after an explosion sparked a fire at a Melbourne laboratory.

Four people were inside the room where the explosion happened at PPG Paints laboratory in Clayton on Thursday afternoon.

Two are suffering from mild nausea and are being treated by paramedics.

Fire crews have tested for readings of a peroxide chemical being used inside the lab at Clayton.

An MFB spokesman told AAP the chemical can be dangerous but there is no risk to the public.

About 150 people were evacuated from the building while firefighters battled the second storey blaze, which took 90 minutes to bring under control.

The cause of the explosion is still being investigated.