@fBoyle-- Absolutely! In fact, you can use sea salt hair spray as a dry shampoo when you're in a fix.
I made my own sea salt hair spray for this purpose a while back. I just used boiled water, sea salt and rose water. I mixed them together and put it in a spray bottle. I usually wash my hair once every two days but my hair becomes a bit oily on the second day. So I use this spray to absorb some of the excess oil. If you spray a lot of it and then use a hair dryer for a minute, it gives a fresh washed look to hair. It smells good too. If you don't like the scent of rose water, you can use a few drops of lemon essential oil.
I think this is something that everyone needs to keep in their bathroom for emergencies. And maybe in their purse too!