My flatmates are chain smokers and they smoke in flat. Due to some reasons I cannot leave their company. I try not to be around them but as we live in same house the smoke might get mixed in the air. I also suffered from a lung infection fees days back. I have a feeling that the smoke might be the reason. Please suggest me some ways by which I can counter the smoke mixed In air. One of my friend advised me about N99 mask that kills 95% of the pollution in air while inhaling. Would that help?