The good news for tourists is that, as in the past warning, most popular areas (including Cancun, the Riviera Maya, Mexico City, Los Cabos, Riviera Nayarit, Puerto Vallerta, San Miguel de Allende, Guanajuato, Merida, Chichen Itza, Huatulco and Oaxaca) are exempted.
Super Chill Mountain Chill Soda Ingredients Carbonated Water, High Fructose Corn Syrup, Orange Juice From Concentrate With Other Natural Flavors, Citric Acid, Potassium Benzoate (A Preservative), Gum Acacia, Potassium Citrate, Caffeine, Calcium Disodium Edta (To Protect Flavor), Yellow 5, Brominated Vegetable Oil
Yes, Baking Powder has a acidic powder mixed with it to create air bubbles, a rising action. Baking Soda does not have this. You could sub if you had some creme of tarter to initiate the soda/acid reaction. Or (depending on the cake recipe) some sour cream, lemon juice, or buttermilk. Still it would be a guess.