I was in LA about 4 years ago and I had trouble breathing outside. This would have helped me quite a bit. Then again, my lung issues are absolutely not the norm! Smoke, Smog and anything like it can put me into coughing fits. It was so bad at one point, that I fell out of a customer's vehicle vomiting on the ground from coughing so hard from the smoke in their car... Needless to say, they were NOT amused.