SCAQMD Orders Aerocraft in Paramount to Temporarily Suspend Hexavalent Chromium-Related Operations

March 16, 2017

Aerocraft Heat Treating Co., Inc. – a metal-finishing facility in Paramount -- has been ordered to shut down all metal processing equipment and operations with the potential to emit the toxic compound hexavalent chromium.

Aerocraft, at 15701 Minnesota Ave., was ordered today to curtail operations by midnight tonight 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 on Dec. 16, 2016.

This is the fourth time since the order was adopted that Aerocraft has had to curtail operations due to exceeding the threshold in the order. Prior curtailments occurred from Jan. 19 to Jan. 27; Feb. 14 to Feb. 21; and March 2 to March 7.

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

Date  Hexavalent Chromium level (nanograms/cubic meter)
 Mar. 5, 2017  0.15
 Mar. 8, 2017  0.93
 Mar. 11, 2017  4.081
 Mar. 14, 2017  6.67
 Average  2.6

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.

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

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 have already begun to execute many risk reduction measures and will continue to do so 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 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.

On March 11, due to a monitored level of 4.08 ng/m3, Aerocraft exceeded the 1.0 ng/m ³ 3-day average. According to Aerocraft, this elevated level was due to a power failure that cut power to air pollution control equipment. SCAQMD confirmed the power outage with the local utility. Under terms of the Order for Abatement, this measurement was not included in a three-day average and as such a curtailment was not ordered. Power has since been restored and SCAQMD has informed Aerocraft that in the future, samples will not be removed from consideration due to power disruptions. SCAQMD has encouraged Aerocraft to pursue zero-emission back-up power as a contingency.