Some very smart engineers are working on this problem of “Diesel fumes”. One of the prospective changes, and in fact, on the way to becoming fully realized, is the conversion of Diesel engines to compressed natural gas, with ZERO particulates, virtually stoichiometric combustion, which is the ideal ratio of air to fuel to allow all fuel to be burned with no excess air, meaning no Nitrogen Oxide complexes (NOx), no carbon monoxide, AND no sulfates.
But even on the short term, the refining of Diesel fuel to higher purity (minimizing sulfur content) and the use of urea injection (to control NOx emissions), has greatly reduced the potential for Diesels to cause any actual pollution.
There is a lot of phony junk science that “proves” one of the two remaining emissions of a Diesel engine, water vapor and carbon dioxide, is a dangerous “greenhouse gas”.
In the concentrations at which it exists in earth’s atmosphere, the most powerful and influential “greenhouse gas” of them all, water vapor, actually works to influence the moderation of earth’s atmospheric temperature. The other “greenhouse gas”, carbon dioxide, is in such minute quantity in relation to water vapor, it has virtually no effect on weather patterns or the regulation of temperature in the atmosphere.
Carbon dioxide makes up only about 350 parts per MILLION of the composition of our atmosphere, while the second most corrosive element in the universe makes up some 200,000 parts per million. Only fluorine is more reactive than oxygen, and neither can remain as an uncombined element for more than a very short while. In fact, if oxygen is not replenished at a very high rate throughout the world, it would be depleted entirely within a very few years. And oxygen requires the presence of carbon dioxide and water vapor to form:
6 H2O + 6 CO2 + (photosynthesis) -—> C6H12O6 + 6 O2
In order to breathe, the plants have to be making carbohydrates. They need to be sucking up huge quantities of carbon dioxide EVERY DAY.
Carbon dioxide is plant food.
Thanks to common-rail pressurized direct fuel injection, diesel particulate filters and injecting urea into the exhaust gas stream to make it easier to remove NOx gases, today’s diesel engines easily meet the Tier 2 Bin 5 emissions standard needed to sell a diesel-powered automobile in the USA. In fact, that’s why the Volkswagen Group (Audi/VW) are tremendously expanding their diesel production lineup in the US market. In fact, a 2013 Volkswagen Jetta diesel sedan is capable of over 40 mpg on the freeway at 65 mph easily.