State of Arizona and Maricopa County air quality crews are monitoring the air near a stubborn transformer fire burning in extreme north Phoenix.
Phoenix Fire Department Capt. Scott Walker said about 35,000 gallons of mineral oil used for cooling, enough to fill two swimming pools, was burning inside one of nine transformers sitting on the ground inside a power substation owned by Arizona Public Service.
"We had a transformer at one of the APS substations burst into flames," Walker said. "We don't know what caused it."
The Department of Environmental Quality has determined the black plume from the transformer fire is nontoxic and poses no health hazard to the public.
"Atmospheric conditions appear to be good for that remaining like that for the rest of the afternoon so that parts been good," said Mark Shaffer, spokesman for the Arizona Department of Environmental Quality.
Shaffer said what's burning is generally found products such as laxatives with little chemical compound.
Holly Ward, a spokeswoman for the Maricopa County Department of Air Quality, said Tuesday the smoke plume is rising and traveling to the west and southwest.
Ward tells The Associated Press county air monitoring stations are not registering any exceptional levels of pollution as a result of the fire at this time.
Shaffer said schools near the fire were also made aware of the smoke in case conditions change.
There are no evacuations with the nearest home about a mile away.
The fire started around 10 p.m. Monday.