The rocket has two tanks, one with kerosene, one with liquid oxygen. I bet the black fireball is the kerosene burning, the white cloud is the liquid oxygen vapo

The rocket has two tanks, one with kerosene, one with liquid oxygen. I bet the black fireball is the kerosene burning, the white cloud is the liquid oxygen vaporizing. Environmental impact is likely small, the kerosene would have burned anyway and there are little other hazardous chemicals on board. (Unlike for example the Proton failure linked by kryptisk above which is fueled with really nasty hypergolic fuels.)