We do not trust the DOT standard.
The impact test used by the DOT imparts a fatal skull injury. This has been known for years.
DOT is also a self certified standard so manufactures of lower repute will change helmet models quickly. Doing so allows them to discontinue a helmet that is claimed to be safe before it is subject to any test since the DOT typically tests randomly and usually after a helmet has been on the market a couple years.
So no, do not accept a DOT only helmet.
For whatever it is worth, there is no definitive test that the premium helmets (which come at premium prices) are actually safer than lower priced helmets in real-world crashes. The data does not exist. But the fact that it doesn't exist does not mean that lower standard helmets are just as safe. Each state and each nation collects data differently and therefore there is no realistic way to PROVE a better helmet is actually better.
Now that said, there are lots of laboratory tests that show the DOT helmets are not as good as the ECE helmets or the SNELL helmets or the SHARP multi-star helmets or the FIM helmets. Actually there are lab tests that prove the DOT standard is fatal to humans. I figure it is best to err on the side of safety. Current ECE 22-05 and current 2015 or 2020 Snell standards are pretty much equal. The new incoming ECE 2-06 standard is better but there are only a handful of helmets tested to that standard. FIM is the best standard of all, but it is mostly a racing standard. I am content with a 2015 or 2020 Snell or ECE 22-05 helmet. But nothing less than that.
FWIW, every standard is higher than the DOT standard and there is no jurisdiction that will actually check to see if you have a DOT sticker on your helmet. But if you buy an ECE helmet and it doesn't have a DOT sticker on it, and you feel guilty about buying a better helmet, you can get DOT stickers at the local flea market, from eBay or from Amazon. They are also on lots of counterfeit helmets that are total crap and don't protect you from a golf ball, let alone a crash, so while I trust major internet motorcycle suppliers there is no way I would buy a helmet from Amazon, eBay or any non-motorcycle specific website that didn't have a serious return policy.
My current helmet meets DOT, ECE 22-05 and Snell 2015 standards. The lovely Mrs_Bob has 1 helmet that meets those same standards and another that meets only the DOT and ECE 22-05 standards, but not the Snell 2015. As of 2020, the Snell standard has become bifurcated and one of their standards meets DOT and the other meets ECE, and I would not trust the 2020 Snell/DOT helmets but I would wear the 2020 Snell/ECE helmets. To my logic the Snell standard has been lowered with their new system. And I simply don't trust anything that is simply a DOT approved helmet. So with Snell modifying their testing to meet the DOT that is sort of a kiss of death. A helmet that meets Snell 2020 + DOT is made very differently than a helmet that meets Snell 2020 + ECE 22-05. So I just go with the ECE 22-05 as the standard. And starting in 2024 the ECE 22-06 will be the gold standard of safety, but, as I previously stated, there are a couple helmets that currently test up to ECE 22-06
Hi
To add fuel to the ECE vs SNELL debate.
SNELL has been resisting the European view for sometime, but gradually they are capitulating and moving closer to the European standard. Way back in 2005 SNELL was funding studies to try defend their position, see ref below.
HIC workshop: final report of workshop on criteria for head injury and helmet standards. A SNELL representative at the conference said SNELL wouldn't use the ECE single hit standard as "it would be too expensive to modify their testing apparatus to accommodate such a change". That is hardly a reason not to update a standard.
If you read the whole document, it is so obvious that SNELL was funding the study trying to make a (very weak) and defensive posture against criticisms to their standards. After reading the document I'm embarrassed for SNELL, in my opinion they threw their good name away. With the benefit of 17 years of hindsight since the paper was published, you can see how SNELL has reluctantly modified their stance, but still holds onto the outdated view that rotational forces are not critical in helmet design and certification.
Undoubtedly helmet makers like AGV, ARIA, SHOEI, etc. due to their own engineering expertise make good helmets that pass the SNELL criteria, but in and of itself SNELL reminds me of NOKIA after Apple brought out the 1st iPhone. SNELL is grappling for credibility and is a dying dinosaur.
PS. SNELL helmets are of a different design to their ECE counterparts even though they might have the same model designation. It would be very rare to find a single helmet that could pass the both standards. This is also discussed in the paper below.
I read another paper where a AGV K4 in ECE and SNELL configuration were tested and the author concluded that the performance was not significantly different over a wide range of test velocities.
Fenner Jr., H., Thomas, D.J., Gennarelli, T., Pintar, F.A., Becker, E.B., Newman, J.A., Yoganandan, N., 2005. HIC Workshop: Final report of workshop on criteria for head injury andhelmet standards. Department of Neurosurgery. MedicalCollege of Wisconsin, Milwaukee, WI