Figuring out we need to change the HVAC air filter

My husband Ted has always had severe dust sensitivities as well as asthma. Ted always keeps an inhaler nearby, especially during peak allergen season and when working out. We had a terrible scare a couple of years ago when we moved into a new home. Ted and I had recently traveled out of the country on vacation, and I believe some of his problems were related to this. After going to see his doctor twice and receiving antibiotics, Ted still was not feeling well. It seemed as if his symptoms got even worse upon arriving home. My husband and I were trying all kinds of methods to help him feel better. He followed all of the recommendations of his doctor, and was also taking vitamins. While Ted still was feeling poorly, a neighbor of ours suggested checking the air filter in our HVAC system. This was our first time owning our own home, so everything about the HVAC system was a mystery to us. I am not sure I even realized that we needed to check the HVAC air filters ever. I was shocked when I saw that our filter was filthy. The people who had owned the house prior to us must also have completely neglected the care of the air filter. Fortunately, Ted and I were able to find a credible HVAC company in the area. We contacted them and set up an appointment for a complete Heating and Air Conditioning inspection. We also discussed various filter options with them to invest in the best air quality. Ted and I had our Heating and cooling filter changed per their recommendation. The technician verified that our furnace and air conditioner were both functioning at maximum capacity, efficiency and reliability. Since we purchased our house in the fall, we were mainly concerned with the operation of the furnace. Ted’s dust sensitivities also improved quite a bit after the replacement of the air filter. I never realized that something as simple as an air filter could create such an impact on our health.