Authorities issued a hazard warning after smoke leaving a metal factory’s chemical analysis lab sent potentially dangerous plumes surging through the suburb.

Crews were called out about 9pm Monday at the ALS Metallurgy plant in Balcatta, a suburb in Perth’s north — triggering DFES to issue a warning urging locals to stay inside, shut their doors and windows, and turn off their air conditioners.

Motorists were also asked to avoid the area, reduce their speed and drive carefully.

Firefighters attended the incident, while police described it as “non suspicious”.

By 10.40pm, DFES confirmed locals would no longer be impacted by smoke or fumes.

On Tuesday morning, a spokesperson said the alert was a “false alarm caused by moisture evaporating through a ducting fan”

“Following last night’s reports of a visible plume at ALS’ Balcatta facility, emergency responders confirmed it was water vapour generated during the normal operation of a drying oven,” a spokesperson for ALS Metallurgy said.

“Cold weather conditions caused the vapour to condense, giving the appearance of smoke.”

Testing confirmed the plume consisted solely of water vapour. There was no fire, no release of hazardous materials, no damage or injuries, and no risk to the community. Operations were not impacted.