HC, CO, NOx, ozone, all of these are only really a problem if you live in an area where too many people live too close together, and the situation is often made worse by local topography, for example Southern California, Denver, Mexico City. In rural areas these pollutants dissipate rapidly, and do little if any harm.

CO2 affects us all, no matter where we live. Its effects are far slower and more insidious than those of the other gases, which cause an acute problem when their concentrations become too great. The effects of climate change are difficult to predict, and while it is true that some areas may see improved weather conditions as a result, it is very likely that such locations will be a small minority of the total.

If you are really concerned about reducing pollution, the only good answer is to walk or ride a bike.

On a more practical note, yet another possibility for reducing the emissions of a 122 would be a B230 swap, from a late 240 or a 740. While it requires fabricating motor mounts, and a few other bits and pieces, it's not that difficult to do, as such things go, and would reduce the output of smog-forming pollutants by at least 90%, assuming you use the stock fuel injection, O2 sensor and cat. However, it would make little or no difference to CO2, as fuel consumption would remain about the same.