Cycling to work may seem the healthy option, but a study has shown that people riding in cities inhale tens of millions of toxic nanoparticles with every breath, at least five times more than drivers or pedestrians.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/cycling-city-green-ride-isnt-healthy-option
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/vehicular-pollution
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health-effects
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/respiratory-diseases
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/health
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/cycles
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/times-india-new-delhi
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/toxins
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/walk-and-cycle