Paul Wertheimer is in the mosh pit because that's his job.

The small, crowded club stinks of sweat and cigarettes, and also marijuana. The ear-splitting music is set forth by heavy metal dinosaur Iron Maiden, six grimacing men old enough to know better. The mosh pit -- that's the area in front of the stage where the rowdiest fans crush together, body-slamming and shoving one another in time to the music -- is throbbing.

Clad in his mosh-pit armor (a long-sleeve flannel shirt, ripped jeans, steel-toed boots and earplugs), Wertheimer slips agilely into the melee. Surrounded by rock fans half his age, he makes his way to the front of the stage, the most intense part of the pit. He jumps up and down, pumps his fist to the beat, shoves back when he's been shoved; like everyone else in the pit, he also helps up the fallen and reaches out to move along the ecstatic "body surfers" -- fans being passed from hand to hand over the top of the crowd.

Asked why any self-respecting 47-year-old would choose to frappe himself in this human blender, Wertheimer smiles, a little embarrassed.

"If I didn't do this for a living, I wouldn't mosh," he shouts over the din. "But sometimes I do get a kick out of it."

A somewhat controversial concert safety watchdog, Wertheimer likes to say he's moshed from Seattle to London, in such hard-core pits as those at Slayer and Nine Inch Nails shows. He wanted to see up close the risks of the mosh pit, where fans have been known to sustain severe injuries, including paralysis. Wertheimer has encountered fans with bloody noses and gashed heads; now and then, an unlucky body surfer ends up cracking his skull on the floor, and other surfers inadvertently inflict damage on their fellow moshers with their flailing combat boots. For the doubters, he keeps a carefully annotated list of his pit time. (Sample: "Black Sabbath, Motorhead, 2/25/94, 2.35 hours of moshing.") And in the past four years, he has lost two watches and a pair of eyeglasses; he's also chipped a tooth, been kicked in the head and acquired a rash on his forearms.

These battle scars, he asserts, give him credibility in his position as one of the most vocal opponents of moshing, one who has taken on the concert promoters who dominate the music industry.

From his office here, Wertheimer runs a consulting firm, Crowd Management Strategies, that campaigns for safer concert environments, particularly the mosh pits. He has consulted with city and county governments as well as concert venues around the country, including USAir Arena in Landover. He keeps a database on accidents and violent incidents at rock shows; at the end of each year, he issues the Rock Concert Safety Survey, a compendium that includes his list of the most dangerous concerts. Some notables from 1995's list? Three youngsters killed at a rock concert in Israel, 60 injured at an Oasis show in London and the troubled final tour of the Grateful Dead.

Another concert that was mentioned in his 1995 survey--although it didn't make the most dangerous list--was the WHFS-sponsored Cranberries show at the Washington Monument in May, where 10,000 rowdy fans showed up when 2,000 had been expected, and the National Park Service ordered the band to stop playing midway through its second song. "Over-promoted," Wertheimer decrees. "A mess."

Wertheimer sees himself as the Ralph Nader of rock-and-roll, standing up for concertgoers everywhere.

"Everyone always wants to blame the fans, but fans are put into dangeroussituations all the time," Wertheimer says. "The fans are always the last to know. . . . You pay $20 to $30 for a ticket and expect a safe environment. But, more often than not, there is no safety net, and that's why fans still die needlessly at concerts and still get hurt by the thousands.

"I know I'm unpopular in certain circles because I'm raising the issue the way it's never been raised before," he continues. "I'm not against rock. I'm not the PMRC {Parents' Music Resource Center} I'm not Senator Dole. I'm not in any way involved with censorship. I believe any kind of event can be held safely if the right planning is done."

In person, Wertheimer seems an unlikely agitator. He lives and works in a high-rise apartment overlooking Lake Michigan in the yuppiefied Lincoln Park neighborhood; generally wears plaid shirts, ski jackets and other preppy gear; and gets around town via mountain bike or an elderly, but rather elegant, BMW.

He is given to windy speeches and self-righteousness. And he has found himself up against some fairly weighty opposition, chiefly concert promoters, the top 20 of which grossed $700 million last year, according to one industry survey. His detractors say he is more interested in making a quick buck and landing on the "Leeza" show than in the actual safety of kids at rock concerts.

"Promoters don't like him because he works against us rather than with us, and he paints a grim picture of the problems," says Jam Productions' Jerry Mickelson, a Chicago promoter who has repeatedly clashed with Wertheimer. "He's only out to make himself a name. That's why he tries to sensationalize things." Moshing, Mickelson argues, is to blame for only one known death in the United States -- 18-year-old Christopher Mitchell, who died attempting to stage-dive during a Life of Agony show in Brooklyn two years ago.

Washington promoter Seth Hurwitz, who runs IMP, thinks that Wertheimer may be overstating the case. "There's a lot of people in this business who try and create jobs for themselves," he says. "{Moshing} has not been a problem for us. . . . The more you try to control something, the worse it can get. It's like raising a child."

But Wertheimer has his supporters as well. "I think he bothers these rock promoters and bands because what he says is absolutely right," says rock critic Bill Wyman. "Anyone who goes to these rock concerts knows how dangerous these terrible, unsafe environments really are. They try to dismiss him as a nobody, somebody who doesn't know what he's talking about, but the fact of the matter is, he does."

Not surprisingly, the event that shaped Wertheimer's unusual career was the nation's worst concert tragedy ever, the December 1979 Who concert in Cincinnati, where 11 fans were killed in a crush of thousands trying to enter the gates at Riverfront Coliseum. Wertheimer was the public information officer for the city then, and was home sick that day. Hearing the news on television, he rushed to the site. Unaware of the stampede, the Who performed inside, while outside emergency personnel were still removing bodies.

"There had been 5,000 people on the outside waiting to get in," Wertheimer remembers. "People had been waiting outside for hours; they were crying and screaming and rushing the doors." He says he'll never forget the aftermath: "I saw bewilderment and chaos and piles and piles of shoes and clothing . . . all over the place, piles! It was like an Auschwitz kind of thing."

He went on to author the city's report on the tragedy after a seven-month investigation into the deaths; Cincinnati still has a ban on festival seating. From there, Wertheimer, a graduate of the University of Kentucky with a degree in communications, went to work at the management firm that runs Rupp Arena in Lexington, ultimately moving back to his native Chicago to work in public relations.

Wertheimer continued to do occasional concert safety consulting, and formed Crowd Management Strategies in 1992, soon after an AC/DC show in Salt Lake City at which three teenagers were trampled to death on the floor of the Salt Palace Arena. The majority of his income, however, comes from a different endeavor, his public relations business, Paul Wertheimer & Associates.

Last spring, the San Diego County Sheriff's Department contacted him about two scheduled Pearl Jam concerts there, and Wertheimer was thrust into the controversy around the long-standing feud between the band and Ticketmaster. For a $280 fee, he provided the department with information on problems at past Pearl Jam shows. Ultimately, it recommended cancellation of two June shows at the Del Mar fairgrounds (one of the alternative venues the band had turned to in an effort to circumvent the mega-ticket broker).

When officials decided to allow festival seating at Chicago's Soldier Field for a Pearl Jam concert scheduled there last summer, Wertheimer was interviewed extensively in the local and national media in the days leading up to the highly publicized on-again, off-again, on-again show July 11.

By then, says Kelly Curtis, Pearl Jam's manager, "it seemed like he was out to get us. . . . He may be on this mission for the good of everybody, and his intentions may be right, but he's certainly doing it in a very wrong way."

By the time Wertheimer headed to the gates, ticket in hand, the Pearl Jam camp was ready for him. For one thing, Mickelson, the local promoter, had posted his picture throughout the stadium. "It was in color, 8-by-11, plastered up all over," Wertheimer says. "It really freaked me out."

Then he headed to the pit. During Bad Religion's set, though, Pearl Jam security consultant Jerry Mele removed Wertheimer from the area. Mele says he made Wertheimer leave because he had shoved a young fan. Wertheimer denies this: "It was a set-up," he says. "I pushed no one."

Wertheimer was taken to a holding area where he was photographed by Eric Johnson, Pearl Jam's tour manager. ("We knew this was the guy who'd been talking us down on the radio, and Eric wanted to take his picture so we knew what he looked like," Curtis says, explaining that the band routinely takes pictures of troublemakers at its shows.) Things got ugly. Wertheimer claims he was surprised and knocked the camera away in "a reflexive motion." Curtis contends that Wertheimer shoved the camera in Johnson's face, resulting in an eye injury. Chicago police charged Wertheimer with battery, and he spent six hours in jail. The case was eventually dismissed by the Cook County Circuit Court.

Curtis says Pearl Jam didn't deserve Wertheimer's criticism. "We spend a lot of time making sure everybody's treated well and nobody gets hurt," he says. "We do padded barriers, there's a lot of water and medical {personnel}, people who come over the barriers are handled gently. . . . {Vocalist} Eddie {Vedder} has stopped a show many, many times if he thought people were getting hurt."

Indeed, some of the most high-profile and effective advocates for safe mosh pits are the bands themselves. D.C.'s own Fugazi simply stops playing if the crowd gets too rough. ("We're not the soundtrack to violence," explains the band's Ian MacKaye.) Billy Corgan of the Smashing Pumpkins has been known to admonish fans to take it easy, and the members of Green Day, who routinely play general admission, non-reserved shows, have issued a long list of dos and don'ts for fans and security.

Mele, who has worked as a security consultant to a number of heavy metal groups as well as Pearl Jam, says security guards can only do so much. That means ejecting fans who try to dive off the stage, using wrestling mats or padded barricades when possible, posting extra guards around the pits and, he says, "talking to the kids, asking them to point out who is causing trouble."

It's not enough, counters Wertheimer, citing the increasing number of lawsuits involving fans injured at concerts as evidence that the industry is not responding. (Insurance premiums are increasing as well, and it's not hard to figure out why: One insurer, Entertainment Insurance Inc., estimates that concert injury claims have increased from 30 in 1994 to 300 in 1995.) Aside from ending festival seating as it's currently practiced, Wertheimer recommends his own "mosher-friendly" guidelines for concert planners, promoters and venues, and also that they follow the National Fire Protection Association's crowd control Life Safety Code. He believes the mosh pit must be isolated from the general audience, with no alcohol or cigarette smoking allowed. Floors and barricades should always be padded. Stage-diving and body surfing should be out, as well as certain types of clothing, such as wristbands with metal buckles or studs or heavily ornamented leather jackets. They've been known to cause some surprisingly gruesome injuries.

The Iron Maiden concert is over: The drumsticks have been thrown, the crowd has thinned, the band has departed and the lights are turned up. Despite three hours of hard moshing, Wertheimer emerges barely having broken a sweat, but nonetheless feeling exhilarated.

"You can tell how rough a mosh pit is by what's left behind," he says, scanning the tile floor. It is littered with the usual bar detritus -- crumpled cups, lighters, an odd sock. "I =don't see any broken glasses or shoes," he says, sounding almost disappointed.

Then, on the way out, he pauses. "Do you see any emergency exit signs?" he asks. CAPTION: On the mosh watch: Paul Wertheimer of Crowd Management Strategies.