Firefighters were censored from telling Morwell residents that they were exposed to dangerous levels of air pollution during the Hazelwood mine fire, new evidence to the fire's inquiry claims.

Health authorities also raised the safe level of air pollution for residents in Morwell without having the new guidelines peer reviewed and still chose not to evacuate after receiving data suggesting the higher threshold had been breached.

Firefighters attend the Hazelwood mine fire. Credit:Jason South

Fire reached the Hazelwood coalmine on February 9 and shrouded Morwell and district in thick smoke and ash for weeks.

In a new submission to the Morwell mine fire inquiry a MFB firefighter with 12 years' experience says he was ordered not to discuss high levels of pollution in the town during the fire.