Accidents happen, but the unfolding chemical disaster in north-east China has prompted too many unanswered questions for the company responsible or the government to be allowed to sweep it under the carpet along with the countless environmental cata­strophes that have preceded it...Why did PetroChina, which admitted that five workers had died in the explosion, not immediately warn of the danger posed by the benzene, now making its way in an 80km slick past Harbin and towards the Russian border?