I cycle from East London to Oxford Street every day, I found Plumelabs' data very strange: the air on the London Oxford street (the most polluted street: http:/

I cycle from East London to Oxford Street every day, I found Plumelabs' data very strange: the air on the London Oxford street (the most polluted street: http://www.independent.co.uk/environment/air-pollution-in-londons-oxford-street-has-already-breached-the-legal-limit-for-the-whole-of-2015-in-9960277.html http://www.independent.co.uk/environment/air-pollution-in-lo...) is better than the Vienna's average, which is considered to one of the cleanest city in Europe (http://www.euronews.com/2015/03/31/how-does-your-city-rank-in-european-air-pollution-survey/ http://www.euronews.com/2015/03/31/how-does-your-city-rank-i...). My nose tells the opposite.