Enter: Aeroseal, a Bill Gates-backed startup that sprays a mist of its proprietary sealant — made with a material similar to chewing gum — into a home's air ducts to seal gaps and other cracks.

Consider upgrading to HEPA (High-Efficiency Particulate Air) filters for better filtration of smaller particles. Leaky ducts can allow dust to enter the system. Seal any gaps using duct tape or ...