probably no effects to be honest. As far as byproducts of any sort of combustion process go you have to have a meaningful context or comparison point to work from to give any amount of anything a meaningful value.

10x .1 = 1

10x 1,000,000 = 10,000,000

10x nothing = nothing

You're trying to improve your gas mileage by running lean and hot. Why not just go for electric, and learn something new?

Why not do both?

Electric for long distances isn't there yet - we still need intermediate techs while the batteries improve.

Cars worldwide are tied to extremely restrictive pollution standards these days but if I was driving across the deserted permafrost of Alaska, for example, does anyone (or any ecosystem) care if I make relatively large quantities of NOx's. If there were a thousand trucks (widely spaced) doing the same as me does the answer change? How about ten thousand?
What's the difference? - Is less CO2 globally worth 'local' increases in NOx or other pollutants? I'm suggesting that it might be worth governments at least considering.

In considering the effects of NOx in GHG terms, you need to look at speciation. The GHG effect that cocerns most people is that from N2O, which is 317 times smaller than that of CO2.

The other reason speciation is important is that the various specie at the tailpipe decompose and recombine at different rates.

As for SOx, once the sulphur is removed from fuel (in Europe was no have zero sulpher fuel; the US is moving to 35 ppm sukpher fuel from 300 ppm) there is no production of SOx. Engine oils are similarly sulphur free.

In your scenario of a lone car miles from anywhere, the effects are likely to be negligible. However, they are not zero and as the number of cars increases so does the pollution.

Another major factor is the weather and topolgy of the area. I think it's Milan than really suffers because the city is in a bowl shaped valley. The pollution settles into the city (similar to what I've read about SF). If you're on the wide open plains, then the local concentrations will be lower.

One more point - if your car is giving out 10x the legal limit of NOx is this because

1. it's "broken"
2. you've retuned/rechipped it
3. it's very old?

If it's 1 - I'd get it fixed as other things will fall off...

Ozone at ground levels kills crops and plants. It is just as much poison to them as is it to us. A quick Google search for the effects of NOX or Ozone could answer all of your questions. Here is a link for K-12 students. http://www.belleville.k12.wi.us/bhs/health/environment/nitrogen_oxide.htm If you are lean burning in an ICE you should look at this white paper first http://www.autoshop101.com/forms/h55.pdf

ozone is O^3. it has no nitrogen in it. Good link for ICE.

http://en.wikipedia.org/wiki/Tropospheric_ozone discusses ozone formation. NO2 is part of it. That is why NOX is a precursor for Ozone.

Nitrogen oxides are fertilizer for plant growth. So are sulfur oxides. The government advised farmers to increase the sulfur in their fertilizer, since air pollution reduction efforts have reduced the SOx available to plants.

Then the fertiizer is targeted.

Being airborne means it attacks the stonework of buildings - as sulphuric or nitric acid - and adds to the acidification of the seas.

I love the myths that go around the rumor mill. They are so entertaining! This one sounds like something my farm hand family friend would say. His stories are usually based on some single instance that has been blown out of proportion. This post doesn't sound much different.

Farmers do soil analysis to determine what nutrients are needed and how to fertilize that particular field. Without the soil analysis in today's method of farming, the farmer won't make any money and will be forced out of business (I know there will be some exceptions to this). The more sophisticated farmers have computer controlled systems that know exactly where to put how much of each fertilizer. The farm hand just drives the tractor.

Also, the fertilizer companies do their own R&D to determine what is the "best" product for their customers. Each company seems to have their own definition for "best".

Exactly. I didn't have time to write that!

GPS controlled fertilizer spreading. Less smelly than just spraying BS about....