While building homes so they are completely sealed does a lot to improve the efficiency of your HVAC system, it also traps pollutants inside. Over time, this results in indoor air quality that is actually far worse than outside air. By installing some air purification tools into your HVAC system, you can keep the efficiency of your system up, while reducing the amount of pollutants inside your home.
All forced air systems have some sort of filter to help trap large particles that could damage your fan. However, the cheap filter you pick up at your local home improvement store doesn't really do all that much to clean your air. The first step is to replace your furnace filter with a higher quality product that traps smaller particles easily. As the filter fills up, it will cease working effectively, and cause additional drag on your fans, so be sure to replace it every few months.
Most HVAC systems don't have enough power to pull a sufficient quality of air through true HEPA or similar high-end filters. If you have allergies and want to explore this option, be sure to have a technician look at your system and discuss your options. In reality, you will probably have to either settle for a lower grade, or invest in single room air filters to reduce particulates significantly.
There is some controversy over whether or not ionizers actually work, but that doesn't mean you shouldn't consider one for your home. The device puts out charged particles that bind to dirt and allergens to make them bigger. The idea behind this is that the bigger particles will either be more easily trapped in your filters, or they will fall to the ground where you can sweep or vacuum them up. The devices themselves are a little on the expensive side, but they are very inexpensive to run.
Not everyone is a fan of UV lights in HVAC systems either, but they do have a relatively large fan base, They work by destroying bacteria and allergens as they flow through your ductwork, Just like your filter, the bulb will require regular replacement to maintain its level of effectiveness. While many people are concerned about the possible side effects of ionizers, UV lights are fully contained within your ductwork, so unless you pull the bulb out and look at it directly, it cannot hurt you.
While no filtration system is perfect, you do have several options that can assist you in getting better quality air in your home. A technician from an air conditioner repair company can easily install some, or even all, of these systems in your home to reduce your exposure to indoor pollution.