I've now been about 30 months without any viral, bacterial or fungal infection problems. I flood my sinuses with a mixture of hydrogen peroxide, baking soda and Kosher Salt, on average, about 2 times per month. I obviously don't have to do it too often, and it works great for me, and it doesn't cost me any money.
I think that my chronic infection problems were associated with my turbinates, so the anti-infective mixture worked very well, for me, since the infected areas were fairly easy to reach.
Flooding one's sinuses will not cure allergies or chemical sensitivities. For that one must make changes to their diet, lifestyle, and environment and/or get allergy shots or take acupuncture treatments.