Stop smoking. Decrease exposure to environmental toxins to include asbestos, pollution. First Step is to perform what is called a Household Detox.  VOCs (volatile organic compounds) are found in many cleaners and are usually kept under a sink in the kitchen or bathroom they need to be removed from the house and placed in an outside are like a garage or shed or place items in a BPA free airtight container if safe. Replace any scented detergents or softeners.  Next, ensure asbestos is not in the home, it can be found in many different products. Pollution is also a factor to consider.