Last year I added UV-C bulbs to my air conditioner. One bulb is placed before my air filter and the hour bulb is placed after my coils in part leading to the opening to the entire duct plan for the house. The bulbs utilize a special ultraviolet light frequency that is so bright that it kills essentially anything that it comes in contact with at close enough proximity. They’re so bright you’d go blind if you stared at one straight for an hour. But for someone like myself with regular seasonal dust sensitivities and awful enough asthma as it is, they’re amazing. I use the highest allergen rated air filter that my hardware store carries and I am thorough and frequent with my Heating, Ventilation, and A/C service and repair appointments. I even have my HVAC duct professionally cleaned every 2 years. Despite all of these attempts at better indoor air conditions, I was still noticing troubles with shortness of breath, headaches, and occasional wheezing and sinus congestion. My Heating, Ventilation, and A/C contractor advised the UV-C bulbs at that point and I promptly tied up an upgrade appointment for the following week. The first month with the bulbs was like a dream, no headaches of any kind and I felt like I could breathe easier with little to no nasal or sinus congestion. They have been really the best investment in my plan yet, however after 8 weeks of use I started to notice a drop in performance. I had headaches again and my lungs weren’t feeling as superb as usual. I assumed that the bulbs would burn out completely when they had expelled all of the ozone gas inside, however I was wrong. You could have those bulbs in their creating light for years after they have been used up completely for their antimicrobial properties. My Heating, Ventilation, and A/C tech put in new bulbs Last weekend I have been residing better again as a result.