How much is too much?
Traffic fumes can contain a complex mixture of substances, many of which are toxic. Some of the things commonly found in traffic fumes include:fine smoke particulates, polycyclic aromatic compounds, nitrogen oxides, formaldehyde, carbon dioxide, carbon monoxide, VOCs and many more. An interesting "partial list" (which is itself quite long!) from the Occupational Safety & Health Administration, of substances which are commonly found in diesel exhaust fumes may be found here. It's quite a complex cocktail!
A recent study has found that diesel exhaust fumes kill throat cells - and that interestingly, biodiesel fumes are less harmful to our health than regular diesel fumes. Another reason to go biodiesel!
Another study has found that traffic fumes cause damage to DNA.
Depending on how close to urban areas / road systems you live, traffic fumes could be entering your home. Also you may be interested to investigate air filters for your car:There are products on the market now that run by being plugged into the car cigarette lighter socket and provide air purification while on the road - could be great for those long freeway journeys or commuting in heavy traffic.
Tetra-Ethyl Lead, once in common use, has now ostensibly been phased out of use as a gasoline additive. It is still available in a few countries, but the concerns over its toxicity led to its withdrawal. ( source:http://en.wikipedia.org/wiki/Tetraethyl_lead ).
The United States Department Of Energy has an interesting page on advanced combustion engines which are
intended to cut emissions of toxic substances. Sounds good!
Now electric cars are beginning to be seen on the roads of the world.
Those poor, primitive, desperate 21st century humans!
Observing the amount of traffic on the roads, and the incessant rat-race of our "modern" lives, it looks as though it will be many years before that glorious day in human evolution comes when traffic fumes are a thing of the past! Perhaps our descendants will picture us, fleetingly, thinking "How wonderful life is in the 23rd century!" - before they turn back to their paradise-like experience and their hyper-pure air, swatting our unpleasant memory from their minds as we would swat a fly...
"When I want toxic soup, I'll order it thank you." -- Anon