It's Earth Day: when a broad spectrum of people and groups embrace all things green.

But one of the big criticisms of this kind of thing is that, come tomorrow, most people will go back to their normal lives and enviro-action again takes a back seat. So against this backdrop, it's a smart move for the state DEC to forgo the feel-good tree plantings or whatever and hold a press conference on a decidedly un-sexy topic: ongoing enforcement of diesel truck emissions standards.

Yes, the DEC is holding an Earth Day crackdown today called the "Stop Smoking Initiative for Trucks." Conservation police - along with the State Police commercial vehicle enforcement unit - are out on Buffalo Road in Gates pulling over trucks that are "churning out plumes of exhaust," as officials put it in a press release.

"Environmental protection isn't just about lakes, rivers, and wilderness. It's about our cities," said Paul D'Amato, director of DEC's Region 8, which includes Monroe and surrounding counties.

The DEC started doing these kinds of sweeps in Manhattan, and they've since spread across the state. By targeting trucks that spew smoke, they're actually targeting particulate matter. That sort of pollution can contribute heavily to asthma and other respiratory problems, said Mike Wheeler, a representative from the DEC's air division. (Likewise, if a truck is emitting too much nitrogen oxide, that can contribute to ground-level ozone.)

Officers measure exhaust with an opacity meter, which determines whether the contaminants are above acceptable levels; that's 40 percent opacity - literally the amount of light the exhaust will block - for trucks built after 1991. DEC officers tested a newer, well-functioning truck to provide the media with a reference, and it registered an 11- percent reading.

The problems can be caused by a variety of issues, everything from a dirty air filter to faulty piston rings, said DEC Conservation Officer Beth Haag.

The idea behind the crackdown is to bring the issue to the public's attention, but to also educate the truck drivers, who are ultimately responsible for making sure their rigs meet legal standards.

DEC and police agencies also target leaking fuel and drivers who exceed the five-minute idling limit for commercial diesel trucks.