KANSAS CITY, Kan. -- Just what was Dale Earnhardt Jr. thinking, anyway?

With his disclosure last week that he not only suffered a concussion in a crash in April's race at Fontana, Calif., but then continued to compete while suffering from post-concussion-related symptoms, Earnhardt not only compromised the safety of the sport, he also soiled what had been a near-flawless reputation.

Junior's crash at California was one of the hardest of his career, sliding sideways and then slamming into the retaining wall head-on.

Many of Earnhardt's fellow competitors have not taken kindly to his lack of concern, not only for his own health but also their fate. No one wants to be on the same track with a driver whose abilities are suspect, at best.

Yet Earnhardt told no one how he was feeling. He admittedly was more concerned with where he was in the championship chase than he was about his or other's safety. As long as he could continue to earn points, that seemingly was all that counted in Earnhardt's concussion-numbed mind.

Earnhardt didn't do himself much of a favor on Sunday's pre-race program on NBC. When asked if he felt his ability might have been impaired by his concussion for the several races that followed California, Earnhardt replied with a joke about something that is no laughing matter.

"Even at 80 percent, I'm probably better than half the guys out there," Earnhardt said with a broad smile on his face.

Then, quickly realizing how inappropriate his statement was, he quickly added, "Nah, I'm just kidding."

In other words, Dale: open mouth, insert foot.

Your life and your competitors' lives are nothing to be "kidding" about. You let down a lot of people by not only waiting five months to reveal the extent of your injury, but then you added insult to your injury by having such a lighthearted reaction. Why didn't you just come out and say, "Aw shucks, it was nothin'.'"

The problem is, it was something. Earnhardt jeopardized more than just himself. He put each and every driver in jeopardy. But that's not all. There's pit road officials, crew members and even fans who could have been hurt due to Earnhardt's failure to use his battered head.

	Earnhardt Jr. was injured at Fontana in April.

At speeds that sometimes approach 200 mph, for a driver to have anything less than 100 percent behind the wheel is completely unacceptable.

I shudder to think what might have happened if Earnhardt had come back the following week at Richmond, Va., and blacked out, with his car traveling 120 mph. If that happened, tragedy would almost certainly have followed, if not for himself, than some innocent victim.

Or, what if Earnhardt experienced the type of vertigo that forced CART drivers to boycott racing at Texas Motor Speedway last year when speeds became unsafe, causing several drivers to come close to blacking out or suffer cases of disorientation.

Imagine if that race was run and a Michael Andretti or Helio Castroneves had blacked out and caused a devastating crash. What if the decision to continue racing cost a life? Would racing ever recover from something like that?

It's probably too late for NASCAR to fine or otherwise penalize Junior. Even though he blatantly admitted his misdeed, the amount of time that has transpired, and the fact no one was seriously hurt -- either directly or indirectly -- would make it difficult for NASCAR to slap any kind of punishment upon him now.

But NASCAR isn't standing still, either. It announced refinements to its medical policy Sunday prior to the race, a direct result of the Earnhardt imbroglio. NASCAR President Mike Helton said if any driver involved in a crash displays concussion-like symptoms while being treated at the infield medical center, NASCAR will require the driver to go to the hospital or undergo some form of subsequent follow-up imaging examination to assure his physical health and mental faculties have not suffered any long-term impairment.

"If there's any doubt, NASCAR will mandate testing," Helton said emphatically.

Ironically, Kansas Speedway, site of Sunday's Protection One 400, was the same venue where Dale Jarrett suffered such a severe concussion in last year's inaugural event that he still has no recollection of the three-day race weekend. His only memory was catching a plane to fly home to North Carolina afterward.

Earnhardt Jr. was wrong, plain and simple. Hopefully he's learned several lessons as a result, and the next time a crash leaves him woozy, he'll realize how much of a threat he was and how lucky he was -- both for his own sake and that of his fellow drivers.

Junior should have known better. Shame on him for treating such a serious subject so lightly.

Jerry Bonkowski covers NASCAR for ESPN.com.