How to choose a fir-tree for new year

Management on SVAO of Department GOCHSIPB reminds: In shops now big variety of fir-trees. We will stop the attention on fire safety of a New Year's symbol. All artificial fir-trees are issued from polymers which when burning allocate harmful substances. The material of which they are made is a polyethylene, polypropylene, polyvinylchloride, etc. Polyethylene and polypropylene a little than differ from each other and continue to burn even if to clean from them fire source, emitting thus carbon monoxide. There are enough some sighs that the person fainted. If not to give help...