Paramount - Ongoing Air Monitoring Activities



Delays to Monitoring Schedule and Results
Due to COVID-19, modifications to the air monitoring schedule have been made and data analysis and posting the results online may be delayed.

Elevated Levels of Hexavalent Chromium
Recently, elevated levels of hexavalent chromium up to 2.2 ng/m3 have been detected at Monitor Number 8 near Aerocraft Heat Treating Co., Inc. in the City of Paramount. South Coast AQMD has been investigating operations at Aerocraft and the surrounding area, and is inspecting permanent air pollution control equipment recently installed at the facility that replaced temporary air pollution controls. This equipment was installed as part of Aerocraft’s Risk Reduction Plan to permanently reduce hexavalent chromium emissions.   Aerocraft is required to conduct additional testing of the permanent air pollution control equipment. South Coast AQMD will  continue its ambient air monitoring for hexavalent chromium and investigate any additional elevated readings. 

Updated Air Monitoring Plan for Paramount
In October 2016, South Coast AQMD initiated an extensive air monitoring campaign to assess levels of hexavalent chromium in the industrialized sections of the City of Paramount. Highly elevated levels were found initially and additional efforts were conducted to identify and address sources of hexavalent chromium that were be impacting nearby communities. South Coast AQMD’s ongoing air monitoring results indicate a substantial progress in reducing ambient levels of hexavalent chromium. As a result, the South Coast AQMD is updating its air monitoring efforts in Paramount to focus on conducting studies to evaluate other potential sources of hexavalent chromium and also monitoring other areas of the Basin that may have higher potential for air toxics exposure. South Coast AQMD will continue to perform sampling at selected locations within the Paramount community and this document outlines the updated monitoring plan for the city of Paramount.


In 2013, the South Coast Air Quality Management District (South Coast AQMD) received a series of metallic odor complaints from local community members in Paramount. In response to these complaints, the South Coast AQMD staff began conducting an investigation into local sources of emissions, including initiating a local air sampling study. The purpose of these activities was to determine the source of emissions and potential air pollution control strategies. Ambient monitoring of toxic metal emissions began in 2013 at two sites on Vermont Avenue and California Avenue. Based on the monitoring results, there were two metals of concern: nickel and hexavalent chromium.  In 2014 and 2015, South Coast AQMD worked with Carlton Forge Works to reduce metal particulate emissions from its grinding operation. Carlton Forge Works implemented a number of voluntary measures that substantially reduced nickel levels. Since these measures did not reduce hexavalent chromium levels, the South Coast AQMD needed additional data to understand the source of these emissions. In October 2016, as part of its ongoing investigation to identify and address sources of hexavalent chromium that may be impacting the nearby communities, South Coast AQMD staff deployed several monitors in the mostly industrial areas of the City of Paramount. Initial results showed elevated levels of hexavalent chromium upwind of Carlton Forge Works. Results of monitoring efforts, South Coast AQMD Town Hall Meetings, air monitoring and public health reports, and other related information are posted on this website.

Summary of Efforts

The South Coast AQMD has undertaken unprecedented, extensive efforts to identify and reduce sources of hexavalent chromium in the City of Paramount. This Summary of Efforts in Paramount (PDF), summarizes the significant progress made and provides highlights of monitoring, enforcement, rule development, public outreach, and coordination efforts.

Potential Businesses with Metal-Related Operations in Paramount

Participating Agencies/Interagency Coordination

Los Angeles County Department of Public Health:

Related Information


Please contact us at 1-800-CUT-SMOG or file a complaint online, if you have information that can assist us in the investigation of sources of hexavalent chromium in the area. If desired, the information can be provided anonymously.

News Releases

South Coast Air Quality Management District

21865 Copley Dr, Diamond Bar, CA 91765



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