Unfortunately, some "skate style" helmets are not actually certified to a skateboard standard. If they meet the CPSC bicycle helmet standard they can legally be sold for bicycling and roller skating. But some manufacturers label their helmets for skateboarding and extreme or trick roller skating as well, and the helmets are not certified to ASTM F1492, which requires a multi-impact helmet.
In-line skating is similar to bicycle riding--fewer crashes, and more violent ones when they occur. So our advice on skateboard helmets differs from that on inline skating helmets. Check our page on skate helmets for the difference. CPSC has a very useful chart of helmets matched to various activities on their Web site.
By law a bicycle helmet must meet the CPSC standard to be sold in the US market. But that law is unique to bicycle helmets, and
there is no US law that says a helmet being marketed only for skateboarding has to meet any standard whatsoever. The manufacturers and retailers are mostly afraid of lawsuits if they don't meet a skateboard standard, but in fact they can sell anything at all as a skateboard helmet as long as they don't market it for bicycling. So for skateboard use look for the ASTM F1492 sticker inside the helmet if it is a "skate" helmet in addition to any CPSC sticker it may have.
Note that some helmets may be certified to F1492 only in some sizes, and not in others. If the manufacturer makes one shell size and just uses thinner foam inserts for larger size heads, for example, the large may not be certified. Or it may be the other way around and the small is not certified. That sticker in the helmet is the only thing you can rely on. It must be there, or all bets are off.
Never accept anyone's statement that the helmet passes without a sticker. That goes for whatever the manufacturer has put on the outside packaging.
We are still finding helmets with "ASTM F1492" on the packaging, but not inside the helmet. The ASTM F1492 skateboard helmet standard requires that there be a sticker inside the helmet. If there is no sticker, the helmet therefore does not meet at very least the labeling requirements of the standard. Any statement just on the packaging (which they know you throw away) is not a certification and means nothing. Packaging and helmet models can be mismatched at the factory, and you don't know what you are buying if you rely only on the box. The manufacturer may have changed the helmet, degrading its performance, but still be using up some old packaging. We do not accept any manufacturer's statement that the lack of a sticker inside is just an oversight.
One of the significant advantages to a dual certified helmet is that
the CPSC bicycle helmet standard test line is lower in front than the F1492 skateboard standard, even though the skateboard standard has a lower test line in the back. So the helmet has to protect in front to a lower point on your head. It only has to offer bicycle protection (single impact) in that area, but at least it is tested at the lower point for one hard hit.