You can often buy 15% Muriatic Acid and if you can get it for roughly half the price of 31.45% Muriatic Acid then it's about as economical. I find that this half-strength fumes a LOT less. Nevertheless, my pool store sells the full-strength at the best price so I still use that and am just careful to be up-wind when pouring. I do measure it in a cup, but I do that pouring away from my face and over the pool.

The good news is that though the fumes are irritating, this is actually a good thing since it warns you well in advance of being too harmful. Nevertheless, it's the nastiest stuff most pool owners will experience with regard to chemicals.