When we’re driving our car, we emit a lot of exhaust gases, one of the most dangerous being CO. Exhaust gases are usually very fine, especially with the modern vehicles. However, that gives us the problem of the fine particles. 90% of all emissions are now smaller than 1 micron (As reference, the human eye can see up to 20 micron and a human hair is 70 micron). Those fine particles get inhaled by humans and come into our respiratory system. Obviously, we have to try to reduce these harmful fine particle emissions, in order to stay healthy. There are already a few solutions available, e.g. the 3-way catalyst (which uses precious metals to transform NOx, CO and Hydrocarbons to less dangerous gases), exhaust gas redirect, etc.
Research on those exhaust gases is being done to improve the quality of the exhaust gases (i.e. reduce the harmful emissions). But just how important is this research? A lot of different researches are being done on everything from fuel to exhaust gas. Mainly the engine is given a lot of attention, but I think there should also be a lot of attention on the exhaust gases. Car manufacturers only research it because of the legislation involved.