Inside the house, opening doors and windows will get rid of a lot of chemicals and odors and a heat or energy recovery ventilation system can also be installed.
A whole-house filtration system with a MERV 16 rating removes 90-95 percent of mold spores, pollen, pet dander and viruses. MERV (Minimum Efficiency Reporting Value) ranges from 1 to 16—the higher the number, the better. MERV 16 efficiency will be more than 95 percent efficient at removing particulates including dust mites, mold spores, fungi, pollen, and pet dander larger than 0.3 microns and more than 90 percent efficient at removing the smallest, breathable particles, such as viruses and bacteria, down to 0.01 microns.
NOTE: a MERV filter requires professional installation.