Depends on the day that's in it. There have been days you could see the particles, not as a haze but as actual individual particles. I don't have asthma and Lon

Depends on the day that's in it. There have been days you could see the particles, not as a haze but as actual individual particles. I don't have asthma and London air triggered exercise induced asthma on hot calm summer days (this was 10 years ago).