On August 12, a fire began at a storage warehouse in Tianjin, China. More than a thousand firefighters were sent in to fight the fire. About an hour after the firefighters went in, two huge explosions registered on the earthquake measurement scale (2.3 and 2.9, respectively). Follow-on explosions continued and at least 114 firefighters, workers and area residents have been reported dead so far, with 57 still missing (at this point, most are presumed dead).
Little is known for sure about what caused the initial fire and continuing explosions. What is known is that the fire, explosions and release of hazardous chemicals that were stored on site have caused significant impacts to the surrounding population and rescuers. These impacts can be used to develop cause-and-effect relationships to determine the causes that contributed to an event. It’s particularly important in an issue like this – where so many were adversely affected – to find effective solutions to reduce the risk of a similar incident recurring in the future.
Even with so much information unavailable, an initial root cause analysis can identify many issues that led to an adverse event. In this case, the cause of the initial fire is still unknown, but the site was licensed to handle calcium carbide, which releases flammable gases when exposed to water. If the chemical was present on site, the fire would have continued to spread when firefighters attempted to fight it using water. Contract firefighters, who are described as being young and inexperienced, have said that they weren’t adequately trained for the hazards they faced. Once the fire started, it likely ignited explosive chemicals, including the 800 tons of ammonium nitrate and 500 tons of potassium nitrate stored on site.
Damage to the site released those and other hazardous chemicals. More than 700 tons of sodium cyanide were reported to be stored at the site, though it was only permitted 10 tons at a time. Sodium cyanide is a particular problem for human safety. Says David Leggett, a chemical risk consultant, “Sodium cyanide is a very toxic chemical. It would take about a quarter of teaspoon to kill you. Another problem with sodium cyanide is that it can change into prussic acid, which is even more deadly.”
But cleaning up the mess is necessary, especially because there are residents living within 2,000 ft. of the site, despite regulations that hazardous sites are a minimum of 3,200 ft. away from residential areas. Developers who built an apartment building within the exclusion zone say they were told the site stored only common goods. Rain could make the situation worse, both by spreading the chemicals and because of the potential that the released chemicals will react with water.
The military has taken over the response and cleanup. Major General Shi Luze, chief of the general staff of the military region, said, “After on-site inspection, we have found several hundred tons of cyanide material at two locations. If the blasts have ripped the barrels open, we neutralize it with hydrogen peroxide or other even better methods. If a large quantity is already mixed with other debris, which may be dangerous, we have built 1-meter-high walls around it to contain the material — in case of chemical reactions if it rains. If we find barrels that remain intact, we collect them and have police transport them to the owners.”
In addition to sending in a team of hazardous materials experts to neutralize and/or contain the chemicals and limiting the public from the area in hopes to limit further impact to public safety, the state media had said they were trying to prevent rain from falling, presumably using the same strategies developed to ensure clear skies for the 2008 Summer Olympics. Whether it worked or not hasn’t been said, but it did rain on August 18, nearly a week after the blast, leaving white foam that residents have said creates a burning or itchy sensation with contact.
View an initial Cause Map of the incident by clicking on “Download PDF” above.