Anyone Familiar with Helicopter Emissions Standards?

(or lack of standards)? This is from my girlfriend's son. Not sure exactly where to post, but will cross-post in environment.

[div class = 'excerpt']Could you ask something on DemocraticUdnerground for me? I want to know if there is a Vehicle Emissions inspection program for helicopters, like the one for automobiles. Also whether there is a guideline or limit to how long helicopters are allowed to idle on a helipad in Baltimore city. The reason is that I work in a University of MD building right next to a hospital with a helipad.

Several times a month, my building would be filled with horrible engine exhaust
smell that causes headache and nausea to a good number of faculty, staff, and students. The cause is the helicopter exhaust getting into our building's air intake. Our building retrofitted some baffles to draw air away from the helipad, but the helicopters are sometimes pumping out enough exhaust to fill the entire area outside the hospital down to the street level. It seems my building doesn't have any other way to deal with this issue other than a costly and slow redo of the
entire air intake system. I wonder if we can minimize the problem from the source, that is, from the idling helicopters.