The girls dashed past a picnic table that had a marijuana leaf scrawled with permanent marker on the tabletop. Next to the drawing of the marijuana leaf were gang statements like "Blue Pride Natives" and "Crips."

One girl scrambled for a piece of equipment that had two small slides descending from the top. Scrawled on the slides, again with permanent markers, were identical representations of male sexual anatomy. Nearby, another picture of a marijuana leaf contained the words "weed for life" around it.

"That's another reason I'm doing this," said Mark Mask, pointing toward the girls. "We don't need to have the kids exposed to it."

Mask is a volunteer graffiti eradicator for the Flagstaff Police Department, and he spent the morning at Smokerise Park on the east side of the city wiping out the dozens of drug and gang references that had been written all over the park.

He volunteers up to 10 hours a week waging war against "taggers," or people who create graffiti. He does it for the children, he said, particularly for his 4-year-old daughter.

"It's a way to give back to the community," he added.

Mask, who has been a painter at Northern Arizona University since 1981, said volunteering for the police department was a natural fit.

"A great portion of my work there has to do with this," Mask said. "And I noticed a lot of places around town not being addressed."

Before he became a volunteer, he reported incidents to police and found out that graffiti eradication uses volunteers and donated materials. Even the graffiti eradication van was donated.

"I said, 'Give me the paint and I'll take care of it,'" Mask said. "They were pretty happy to see me come in."

While Mask's daughter is in school, he heads to the police department to check the graffiti hotline for calls from residents notifying him of graffiti in the city. He also has a box at the department where officers give him reports of graffiti they've seen on their beats.

"That's what brought us here today," he said, pulling out a police report from the graffiti van. A crime stop caller

contacted police, and officers came to the park to document the damage.

Using permanent markers, the taggers left some kind of gang, drug or sexual reference on nearly every piece of equipment at the park.

Mask pulled out a gallon tub of lacquer thinner.

"I've got every graffiti remover known to man," Mask said, smiling. He starts out with the less toxic, and moves to the higher-strength stuff depending on the veracity of the graffiti's staying power.

If he can't remove the graffiti that way, he paints over the graffiti.

All the materials are donated.

A large part of his work is on the eastside, particularly Sunnyside, he said.

"But it's all over," he added. "Slowly but surely, I'm cleaning it up. I'm getting on top of it."

His tagger nemeses come in two types: Gang affiliates and lone wolfs.

Of the gang graffiti, Mask said, "A lot of these guys like to complete for little areas in town."

So eastside people tag on the westside and vice versa in order to state a perceived ownership of turf. Mask said he thinks most of these types of taggers are not gang members per se, but people who want to be gang members for whatever reason.

Lone wolves are the type who either deface someone else's property once, or they are individuals who specialize in a particular style and area.

Of the taggers who develop a style and focus on one particular area, Mask said that sometimes a game develops between himself and the tagger.

"It's a little cat and mouse-type thing," he said, adding that he'll find graffiti, remove it, and a week later, new graffiti by obviously the same tagger will be back. But that's good, Mask said, because it helps police get a bead on who's doing it and might lead to arrest.

He recalled a recent lone wolf on the campus of NAU.

"His tag became very apparent and noticeable," Mask said. It will be only a matter of time before the tagger is caught or graduates and moves on.

Chris Permar, 20-year resident of Smokerise, brought her niece and her niece's two friends to the park Wednesday.

"It's maddening," Permar said. "It makes you mad that kids do that."

Being exposed to the graphic drug, gang and sexual references is not good for the children, who do notice, she said. Maybe not children her niece's age, but school-age kids for sure.

"They deface stuff that doesn't belong to them," Permar said. "Why ruin it for other kids? I just don't understand how somebody can do that."

Permar said that she has seen the level of graffiti in the park rise and fall in stages. She guessed that perhaps the kids who had been doing it in the past grew up and moved away, only to be replaced with a new crop.

Of Mask's work, Permar said, "I think it's great. You think about cleaning it up, but I don't know how to do it."

A short time later, Permar and Mask spoke. Just before Mask went back to work wiping out two penises that had been drawn on the small-children slides, Permar said, "Thank you for cleaning it up."

"I've fund that people are pretty happy to actually see stuff happening," Mask said.

Sgt. Gerry Blair of the police department said graffiti is a crime, under criminal damage, which could range from a misdemeanor to a felony depending on the extent and cost of the damage.

The department's interest is based on the notion that graffiti that is not eradicated increases a neighborhood's likelihood to attract criminal elements.

"It's like the 'broken windows theory,'" Blair said

A criminal who visits a neighborhood with broken windows, abandoned cars, trash everywhere and graffiti everywhere.

"It may send the message that people in that neighborhood really don't care," Blair said. Neighborhoods that are kept clean, with windows fixed and graffiti eradicated sends a message that residents do care, and therefore, creates a poor target for criminals.

And Blair was adamant to say that, to him, graffiti is not art, as some people might say. It is a crime.

"If it's art, paint it on your house or your property, not other people's neighborhoods and property," Blair said.

Public awareness is key to cutting down on graffiti, Mask said. Most people simply do not notice graffiti.

"We need people to open their eyes, be vigilant and call immediately," Mask said.

The stories from people of "why bother, the graffiti will just return" doesn't wash for Mask.

"We're not in that kind of game," he said.

To report graffiti, contact the Flagstaff Police Department graffiti hotline at 556-2311.