In a major fire at the Dow Chemical plant during the summer, a substantial amount of the highly carcinogenic chemical ethylene oxide was released, equivalent to almost a decade's typical emissions from the facility, according to a recent company estimate. This incident, which occurred in mid-July at the Dow complex north of Plaquemine, led to the release of ethylene oxide along with at least 17 other chemicals and tiny respiratory system-irritating particles.

Dow officials have confirmed that these emissions occurred during the initial explosions and in the weeks that followed as the company worked to clear lingering chemicals from the equipment. The cause of the fire, which burned for a day and a half between July 14 and 16, is still under investigation, with Dow committed to providing follow-up reports to state regulators.

The consequence of the fire had substantial repercussions, compelling both local and state authorities to take action by closing down highways and issuing guidance for hundreds of residents to stay indoors, keeping their windows closed and air conditioning switched off as a precautionary measure.

Ethylene oxide, a highly flammable and colorless gas, was among the chemicals released during the incident. Prolonged exposure to it is known to be a potent human carcinogen, as per the U.S. EPA. Although it is used in the petrochemical industry and medical sterilization, it gained attention over the past decade after the EPA determined it to be more carcinogenic than previously thought. Federal air pollution risk data indicate it contributes significantly to carcinogenic risk in certain areas along the Mississippi River, leading to calls for emissions reductions.

The majority of the ethylene oxide release occurred during the initial explosion, with additional emissions during the subsequent fire, all within the first 12 hours. During combustion, the gas transformed into less hazardous compounds.

Despite Dow's assertions and monitoring, local environmental groups remain skeptical, particularly after a major fire at the Marathon Petroleum Co. oil refinery in Garyville raised health concerns among residents.

Dow's report submitted to state regulators placed strong emphasis on the thorough evaluation conducted by third-party experts to guarantee the precision of emission estimates. In addition to ethylene oxide, ethyl chloride emerged as a notable release, exceeding the total statewide emissions for 2021. Furthermore, various other chemicals such as ethylene, methane, and a range of volatile organic compounds were also discharged, with the majority of these releases occurring within the initial 12 hours of the incident. This comprehensive assessment underscores Dow's commitment to transparency and accuracy in addressing the environmental impact of the event.