There are people with CFS, whose symptoms go away when they leave their house for a few days. This boils down to toxins in the air. Particle Filters Consider filtering your air. The extent to which you do, will depend upon your location and sensitivity. If you have a central air heating system in your home, it will probably have a filter.
Most filters are inadequate because they let the small particles get through.
A human hair is about 70 microns in diameter. Check your system to see if it will accommodate a one inch thick filter, which is fairly standard. Examine the edge of the filter for a label stating it's size, or measure it. Replace your present filter with a high efficiency filter that will trap particles in the 0.3 to 1 micron range. The filter I recommend is the Micro Allergen 1000 or the Ultra Allergen 1250 made by the 3M company .