The one hour you spend in your car daily probably isn't going to mitigate what you're breathing in every day outside the car, if that's something you care about.
http://www.theguardian.com/environment/2015/jul/15/nearly-95...
> Nearly 9,500 people die early each year in London due to long-term exposure to air pollution, more than twice as many as previously thought, according to new research.
> The premature deaths are due to two key pollutants, fine particulates known as PM2.5s and the toxic gas nitrogen dioxide (NO2), according to a study carried out by researchers at King’s College London.
> The study – which was commissioned by the Greater London Authority and Transport for London – is believed to be the first by any city in the world to attempt to quantify how many people are being harmed by NO2. The gas is largely created by diesel cars, lorries and buses, and affects lung capacity and growth.
And your comment reminds me of the discussions about DPF(diesel particulate filters) - they are installed in diesel cars to reduce the soot emissions, but of course, instead of being happy, people complain that there is yet another part that can break down and which will need replacing("why can't cars be as simple as they were 10/20/30/40 years ago" - pick your own decade depending on the age of the person talking).