P.O. Deryk Blair has one barometer for measuring where he is on the job. “What it comes down to is, do I come in with a smile and do I leave again with a smile? If I do, no problem. If I don’t, problem.”

By his own estimate, Blair hasn’t had too many reasons not to smile lately. The 45-year-old native of Panama has had a front-row seat for 22 years to the changes that have overwhelmed the Ninth Pct. and he admits to having to pinch himself every once in awhile to be sure he’s still working out of the same command. “How many numbers you want?” he laughs. “We used to have 40 or 50 homicides a year, now it’s down to three. In the ‘80s and early ‘90s, you could count on every sector car getting at least 20 calls a tour. Lately, you get five or seven and you think of it as a busy night. I’ve been here when we’ve had only one sector car out.”

For all that, though, Blair isn’t about to sing the praises of the NYPD as the ideal career. “I’ve got a 24-year-old son,” the PBA delegate says, “and I told him, forget it. Anything you get out of this job is what you get despite what they want down at Police Plaza. You get exceptions, but this job started going south when the guys from the street promoted upstairs were encouraged to forget where they came from, to act like they’d just been dropped into their new ranks from the sky or something. Maybe there are bigger drawbacks to the job than that, but I can’t think of any. It’s something that affects every hour you’re in uniform.”

Asked what changes he would institute if he were commissioner for a day, Blair doesn’t hesitate to tick off three. “First off, you’re wasting time talking about money because that’s not something that’d be in my control, so forget that for now. But there’s really got to be more respect for seniority around here. Some new guy comes in fresh from the Academy, someone upstairs likes him, and suddenly he’s skipping some of the bad details that the people with time on the job are doing.

“Number two, you got equipment problems that should embarrass the Department. We’re in cars that might’ve been given to us by our worst enemy. That’s partly our fault, too, because we just don’t take care of them like we should. But the bottom line is, the NYPD may be the Finest, but the equipment we have is anything but.”

And number three?

Blair acknowledges his proposal wouldn’t please a lot of cops. “What I consider a pretty basic thing — physical fitness. As far as I’m concerned, I’d have nothing at all against having to do the physical entrance exam every year or two. Guys can talk about lifting weights all they want, but sometimes that’s not the point. When you’re out on the street, you need the guy covering your back to get his fat ass over a fence. If he’s out of shape, he’s not going to be able to do it.”

As for his time on the streets, the Laurelton resident knocks wood that he’ll continue to be able to say he’s never had to fire his weapon. “There’ve been some bad times. For instance, I was one of the 12 cops down in Tompkins Square when all hell broke loose over the tent city the squatters had there back in ‘88. But maybe the time I still get tiny chills about was a call to a house where a baby had turned blue. My partner gave it mouth-to-mouth, and the baby threw up right in his mouth. We run the child downstairs to the car. I’m driving, my partner’s in the back with the baby. We get to the hospital in time, but then the doctors tell us the kid has AIDS. My partner had to take that cocktail. I really count myself as lucky I did the driving that night.”

Blair’s idea of a good time is being a couch potato. “Not for TV,” he says quickly. “I just go through every novel Tom Clancy and James Patterson have ever written. It’s in the bookstores on Monday, I’ve got it home on Tuesday.”

And when he hangs up his uniform for the last time?

“I see myself going down to this area of North Carolina I’m familiar with, buying a house and improving my poker game,” he laughs. “If I can’t smile at the end of those days, then there’ll really be a problem.” — Donald Dewey