These are NOx[1] species not N2O. They do not get into the upper atmosphere, like the ozone layer in the Stratosphere. They are instead constrained to the Tro

These are NOx[1] species not N2O. They do not get into the upper atmosphere, like the ozone layer in the Stratosphere. They are instead constrained to the Troposphere, where we live. NOx emissions are highly reactive and in the presence of sunlight turn into O3, Tropospheric Ozone [2] the same chemical compound as that in the Stratosphere, but very different in it's effects. In the Troposphere, Ozone is a highly reactive oxidizing agent and can have serious negative health effects. You can look at a map of daily ozone generation [3] from pollution. Peak production of ozone occurs at the part of the day where sunlight is most intense following the highest levels of traffic. It then mostly reacts and then levels drop again at night. [1] https://en.wikipedia.org/wiki/NOx https://en.wikipedia.org/wiki/NOx [2] https://en.wikipedia.org/wiki/Tropospheric_ozone https://en.wikipedia.org/wiki/Tropospheric_ozone [3] http://www3.epa.gov/airnow/2010/20100929/anim_aqi_sanfrancisco_ca.gif http://www3.epa.gov/airnow/2010/20100929/anim_aqi_sanfrancis...