A week has passed since the deadly explosions in the city of Tianjin, but government authorities are still struggling to answer a slew of questions in the aftermath of the tragedy. The state news agency Xinhua has published a report asking four questions, which it said the public were most concerned about, as it tried to shed some light on the cause of the explosions which have killed at least 114 people. But Xinhua said its conclusions did not represent the official findings. 1. What caused the explosions? An official at Ruihai International Logistics, which owns the warehouse in the port area of the city where containers of hazardous chemicals were being stored at the time of last Wednesday’s blasts, has said that chemicals stored in the containers may have exceeded safety limits. This may have led to increased pressure forcing open a valve on top of the containers housing the chemicals, Xinhua reported. Any release of chemicals could then have led to them catching fire, causing ammonium nitrate, a chemical that produces toxic fumes and exacerbates combustion of materials found in other chemicals, which then led to the explosions. Several management officials at Ruihai recalled that there were at least “20 to 30 containers” filled with nitrate chemicals at the scene of the fire, each holding about 20 tonnes. At least 10 of its containers contained ammonium nitrate, and seven to eight others contained potassium nitrate and calcium nitrate – all of them dangerous chemicals that can release toxic fumes. Read more: Tears as Tianjin mourns victims of warehouse blasts in commemoration ceremonies across city 2. How are authorities dealing with water drainage problems in the blast zone? Water pipes in the central area of the blast site run across an area of 10,000 square metres. According to state media, at least 40,000 cubic metres of water stored in the area contained cyanide. The latest inspections carried out on Monday showed that levels of cyanide were 1.7 times above normal safety levels. Xinhua reported that the contaminated water would be purified and disinfected by specialised water treatment companies to break down the cyanide. This treatment would also prevent long-term pollution of the soil, groundwater and seawater. 3. Will the area surrounding the blast site be contaminated? Water tested at 40 water monitoring stations in the area on Monday contained high levels of cyanide, with some samples showing 28.4 times more cyanide than normal safety levels, Bao Jingling, chief engineer at the Tianjin bureau of environmental protection, told a press conference on Tuesday. A dam has been built around the central area of the blast site to prevent any contaminated water from leaking into other parts of the city. Air quality in the city is being closely monitored, with data released to the public every two hours. Rainfall in the city on Tuesday also caused fears that it would react with chemicals at the blast site and lead to the release of toxic gases, but monitoring stations said that levels of hydrogen cyanide, a toxic gas released from sodium cyanide, were well below national safety standards. Watch: protests by angry Tianjin homeowners grow following deadly blasts 4. Has the government relocated affected residents? City officials have set up temporary shelters in 12 schools and three residential complexes, which can house up to 15,000 people. Hundreds of residents displaced since the deadly blasts have been supplied with food, medication and daily necessities. According to initial investigations, at least 17,500 houses suffered damage to their windows and doors from the blasts. By Monday more than 700 of these properties had undergone repairs. Police have been accompanying residents back to their homes in seven of the seriously affected areas to pick up what is left of their belongings.
