Second Curtailment of Aerocraft Emissions

Aerocraft Heat Treating Co., Inc. – a metal-finishing facility in Paramount — was ordered to shut down all metal processing equipment and operations with the potential to emit the toxic compound hexavalent chromium by midnight of last night.

Aerocraft, at 15701 Minnesota Ave., will have to shut down all equipment with the potential to emit hexavalent chromium because South Coast Air Quality Management District air monitoring data found levels of the compound above a trigger threshold of 1.0 nanograms per cubic meter.

The level is an average of three samples collected over a period of about a week. The threshold, agreed to by Aerocraft, was specified in an administrative order adopted by the independent SCAQMD Hearing Board.

The following table shows recent levels of hexavalent chromium at a SCAQMD monitor just outside of Aerocraft:

Hexavalent Chromium level (nanograms/cubic meter)
February 7
February 9
February 12

Aerocraft will not be able to resume operations of any equipment with the potential to emit hexavalent chromium until SCAQMD determines that the average of the three most recent samples, collected over about one week, are below 1.0 nanograms per cubic meter.

“Yet again Aerocraft has failed to comply with their abatement order, and it raises serious concerns about their hexavalent chromium mitigation controls,” said Mayor Daryl Hofmeyer. “The City of Paramount will continue to fully support SCAQMD’s enforcement efforts, but if repeated spikes in emission levels at Aerocraft occur, we will request that SCAQMD ​take even stronger measures. In the meantime, our community will discuss all possible actions through the Air Quality Sub Committee.”

SCAQMD, in conjunction with the California Air Resources Board, also has monitored air quality at seven schools in Paramount. Recorded levels at those schools have been below 0.3 nanograms per cubic meter since sampling started on Dec. 23, 2016. Sampling will also be conducted at other schools in Paramount.

SCAQMD found last fall that Aerocraft and Anaplex Corp. were the source of high levels of hexavalent chromium emissions through an exhaustive and fast-paced investigation including:

  • An unprecedented, intensive monitoring campaign that deployed multiple air monitors in an industrial area of Paramount and found high levels close to the facilities; and
  • Emissions tests of equipment inside the facilities that also found high levels of the compound.

Hexavalent chromium is a potent human carcinogen associated with lung cancer when inhaled over long periods of time, typically years to decades.

SCAQMD has required Anaplex and Aerocraft to develop health risk assessments and risk reduction plans under the state’s Toxic Hot Spots program to ensure these facilities reduce all toxic air contaminants to health-protective levels. While some actions may take longer to implement, the facilities will have to start executing many risk reduction measures over the next few months.

Members of the public can find information on SCAQMD’s air monitoring and enforcement activities in Paramount at

In addition, the public and the news media are invited to join a weekly conference call on the status of SCAQMD’s Paramount activities on the second and fourth Tuesday of every month starting at 6:30 p.m. To participate, call 866-244-8528 and use the passcode 4063768.

A simultaneous Spanish translation of the call is available by calling 888-394-8197 and using the passcode 9891238. The calls are listen-only, however questions may be submitted by email during the call to Questions are answered during the call in the order received.

The SCAQMD is the air pollution control agency for Orange County and major portions of Los Angeles, San Bernardino and Riverside counties.

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