Many states in the US have vehicle emissions programs which track that type of data. Most of these programs are in cities with high ozone and the program is required as part of emissions reductions regulations. Depending on what exactly you are seeking, i can point you to companies that make the emissions monitoring machines used or a connection to the cities which have such programs.

Another aspect of age related pollution impact is the design of the engine and pollution controls added. In the US, various regulations caused newer vehicles to be inherently lower emission vehicles. These would represent step changes at certain points in history. May I greet you here, Mark Peak. I met you at an A&WMA conference.

Greetings Mark Sankey. I agree with your premise and concur that the US autos are subject to different requirements than other countries and as such emissions data needs to be viewed in that light. Regardless, emissions have been monitored for since the 1990s, so there is likely a good historical record where the programs have been in place. Technology for measurement has changed through time, moving from straight idling emissions to using tractoin machines to get information that reflects the range of normal operations.

Thank you for the follow up, Mark Peak. You are plugged in more closely to this issue. I appreciate this site for the international connections. No borders here. Simply the desire to share experience for the common good.