For working in a field like firemen which is an important job as they are saving lives, they are required to shave beards off to wear mask as a necessity as without it they have high chance of death due to the gasses. In this case is one sinful for taking this job and shaving or does is if necessity

Ustadh AbdulAziz al-Haqqan

Pursue another career, may Allah give us and you success, ameen.