CHARLOTTE, N.C. -- NASCAR set an age requirement of 18 for participants in its major series, another move in its push for stronger safety measures.

"It was in the best interests of safety, competition and professional development that we institute these new age requirements," NASCAR President Mike Helton said Thursday. "Younger competitors need as much experience as they can accumulate before competing at NASCAR's professional levels."

Beginning in 2002, all drivers, crew members and other participants in the Busch Series, Craftsman Truck Series and all NASCAR Touring Series' must be 18 or older in order to compete. The age requirement matches the existing standard for the Winston Cup Series.

The age requirement will immediately affect drivers like 16-year-old Kyle Busch, younger brother of Winston Cup driver Kurt Busch.

Kyle was scheduled to run the full truck schedule next year for Roush Racing, but will not be allowed to compete under the new rule. Roush, who also owns Kurt Busch's Cup car, plans to keep Kyle under contract.

Kyle's age came up in November when sponsor Marlboro prevented him from racing in a Craftsman Truck race. The objection from Marlboro was based on an interpretation of the agreement between big tobacco companies and state attorneys general that precludes the involvement of people under 18 in events sponsored by the companies.

Under the new requirement, the sponsor issue would not have come up because Kyle Busch will be prohibited to race in major NASCAR-sanctioned events for at least another year.

Also, drivers like 21-year-old Casey Atwood will be less likely to break into Winston Cup until later in their careers.

Atwood was 17 and had become the youngest pole winner in Busch history when he caught Ray Evernham's eye in 1998. Evernham had Atwood continue to hone his skills in the Busch series then hired him to drive one of his Cup cars this year.

But under the new requirement, drivers like Atwood will be relegated to the low-level NASCAR Weekly Racing series, likely pushing back by years the time they will be ready for Winston Cup.

Helton said that was NASCAR's goal in setting the age requirement, as well as a concern over the welfare of minors.

"They need to hone professional driving skills, knowledge, and judgment that is best learned at the local level, as with the Weekly Racing series," Helton said. "After the age of 18, and with this experience, younger competitors should be better prepared for regional or national competition.

"We also considered the possibility of a young person's education being interfered with, by the demands of competing in our larger divisions. NASCAR values education, and would never want our racing to be a distraction in that pursuit."

Other rule changes passed this week included the requirement of helmets and fire suits to be worn by over-the-wall pit crew members and a mandate that any crew member involved in fueling the car must wear a full-face helmet and a fire-resistant "head sock."

And for the first time ever, the rules book will require drivers to wear a firesuit. Before now, NASCAR had only recommended that a driver wear fire resistant clothing but there was nothing in the rule book that prevented a driver from climbing into the car wearing shorts and a T-shirt.

NASCAR also said Thursday that fire extinguishing equipment must be located inside the race car within the driver's reach and must have a visible, operative pressure gauge.