The best way to avoid most chemicals, GMOs, artificial sweeteners, high fructose corn syrup, excess sugar, and low-quality salt is to eliminate junk food, processed foods, and soda. Cut down on meat, and avoid dairy and gluten to reduce excess mucus. Also, add ginger, onions, garlic, and cayenne pepper to help clear excess mucus.
Exercise more outdoors, away from traffic if possible. Breathing exercises like this one can help strengthen lung tissue. Yoga offers some, and there are others as well.
If you have a garden, don’t use commercial pesticides because they are toxic: they emit caustic gases or vapors that irritate the lungs. There are alternatives that are non-toxic to humans and animals.