THIS will definately keep the dust out. And should be able to still use you open face helmet!!
OK, Seriously. When I was offroad racing I had a Simpson Voyager Sidewinder Helmet. This is what they look like now.
Mine looks like this.
It came with a fitting for an air blower to keep a positive pressure in the helmet keeping dust out and your head cool.
I took a quick run around with Google, and all I can find are the filtered blowers that would mount is the car somewhere. I used to have one that had a small blower that mounted right on the fitting. It worked great, was light but I don't think they make them any more.
Check that !!! I just remembered the name,
Fresh Air Systems.
12volts powers it up!
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I live with fear everyday, but sometimes she lets me race.
yea, it's an old one, but is fits.