On November 22, the U.S. Chemical Safety and Hazard Investigation Board (CSB) released an update on its investigation into a September 29 chemical reaction and toxic gas release at the Bio-Lab, Inc., facility in Conyers, Georgia. The incident led to a massive fire and plume of toxic smoke that threatened the surrounding community and the metropolitan Atlanta area.

Roughly 17,000 people in the surrounding community were reportedly evacuated, and nearly 90,000 people in metropolitan Atlanta were advised to shelter in place. Interstate I-20, which runs parallel to the Bio-Lab facility, was shut down for roughly 18 hours, and smaller roads were closed longer. Nightly shelter-in-place warnings to the surrounding community continued for several weeks after the incident, according to the CSB. The warehouse at the Bio-Lab facility was destroyed.

The primary substances involved in the reaction were trichloroisocyanuric acid (TCCA) and sodium dichloroisocyanurate (DCCA), along with bromochloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH). The chemical reaction involved materials stored in a warehouse that generated heat, leading to the decomposition of the product, the release of toxic vapors, and fires.  

The resulting plumes of toxic smoke contained chlorine and other hazardous substances, causing significant off-site impacts.

The CSB’s update outlines the events surrounding the massive blaze.

At 5:00 a.m. on September 29, a Bio-Lab employee on fire watch in the Plant 12 storage warehouse heard what was reported as a popping sound, which the employee attributed to wet product. There were no visible flames at the time. After an unsuccessful attempt to isolate the reacting product, the employee called the only other Bio-Lab employee on-site. 

At approximately 5:10 a.m., the employee called 9-1-1 due to the large hazardous plumes of toxic vapors inside the building. By 6:30 a.m., flames became visible above the area of the chemical reaction and were extinguished in less than 2 hours.

Emergency responders began evacuations shortly before 12:30 p.m. after a second, larger fire broke out at Bio-Lab's Plant 12. The second fire was reportedly extinguished by 4:00 p.m.

The Environmental Protection Agency (EPA) conducted air monitoring throughout the incident, finding elevated chlorine and hydrogen chloride levels from September 30 to October 2, with the highest levels occurring during nighttime hours.

“This incident and the substantial potential risk that it posed to the surrounding community was completely unacceptable,” CSB Chairperson Steve Owens said in an agency statement.

“Reactive chemical incidents can have severe environmental and public safety impacts due to the combination of fire, toxic gas emissions, and hazardous materials involved, and Bio-Lab and any other facility that has reactive chemicals onsite must manage those materials safely.”

The CSB’s investigation is ongoing, as the board’s investigative team continues to gather facts and analyze several key issues, including the following:

• The cause of the material decomposition, release of toxic vapors, and fire;
• Storage and handling of oxidizers and their compatibility;
• Best practices for responding to emergencies involving bulk solid oxidizer chemical reactions and decompositions; and
• Regulatory and industry guidance on fire protection systems for bulk solid oxidizers.

The CSB will provide complete findings, analyses, and recommendations when it issues its final report.

The board investigates chemical incidents to determine a cause or probable cause but issues no citations or penalties. The CSB makes recommendations for companies, industry groups, standards-setting organizations, and other federal agencies, including the EPA and Occupational Safety and Health Administration (OSHA). The board has 12 open recommendations for OSHA.