https://www.helmet.beam.vt.edu/equestrian-helmet-ratings.html
This is a good place to start for helmets. They have the same sort of ratings for different sports so if nothing in the equestrian list looks good, you should check the bicycle list. Note that it's not necessarily current for everything but it's a good starting point.
https://en.m.wikipedia.org/wiki/The_Water_Knife
This was a pretty good read, also rather uncomfortable. I live in Arizona and I worry about the future here for my kids.