Totobobo filter after one month cycling in London

Cyclist Engineer Architects was shocked to see the drak patch collected on his Totobobo filter after one month cycling commute (5.5 Miles per trip) in London. He now recommend that everyone wears an anti-pollution mask on their daily commute.

What would you see on the filter after one month cycling in your city? See how to choose the best cycling mask for pollution.

Source:
Cyclist reveals filthy face masks after commuting in London
https://www.standard.co.uk/news/london/cyclist-reveals-filthy-face-masks-after-commuting-in-london-9901951.html#comments-area