UV-C germicidal air sanitization.

Yes - within limits. UV-C light at the 253.7-nanometer wavelength damages the DNA of mold spores, bacteria, and viruses passing through the air stream. Coil-mounted lamps work the best because they sit on a wet surface (the evaporator coil) where mold loves to grow and the lamp can hit organisms continuously. In-duct lamps work in real-time on air moving past, but the air's only in front of the lamp for a fraction of a second, so they're less dramatic than the marketing suggests. UV-C is a real layer in an IAQ stack - it's not a magic bullet that replaces filtration.

Yes - UV doesn't catch particles, it only kills living organisms. Dust, pollen, pet dander, smoke - UV-C light doesn't touch any of that. You still need MERV-rated filtration for particles, and you still change the filter on the same schedule (90 days standard, 60 days with pets or allergies). UV is a complement to filtration, not a replacement.

Every 12 months. UV-C output drops 15-20 percent per year even when the bulb is still lit - the visible blue glow stays the same but the germicidal kill rate degrades steadily. After 2-3 years, a UV-C lamp is barely doing anything useful. We tag the lamp with the install date and recommend an annual replacement that gets bundled into the spring AC tune-up or fall furnace tune-up. Skip the replacement and you have what amounts to an expensive nightlight.

Standard 253.7-nanometer UV-C does not generate ozone. That's a different wavelength (185 nm) used in industrial applications. Some marketed 'UV air purifiers' specifically generate ozone as part of their oxidation claim - we don't install those. Ozone at the concentrations needed to kill pathogens is also harmful to your lungs, and EPA has been clear that ozone generators are not appropriate for occupied spaces. Our installs use standard germicidal UV-C, ozone-free.

Indirectly. UV kills mold and bacteria, which removes a category of allergen and a category of irritant. It does not catch pollen, dust mite waste, or pet dander - those are particles, not living organisms. For a household with allergies or asthma, the right answer is the full stack: MERV 13 filtration to catch particles, plus UV-C at the coil to kill what gets through, plus (in a tight home) an ERV for fresh-air exchange. UV alone won't move the needle much on allergy symptoms; the stack does.

Coil sterilization is the higher-ROI install for most NE Ohio homes. The wet evaporator coil is where mold and biofilm love to grow in summer - the lamp sits a few inches off the coil and bathes it continuously, keeping it clean. Side benefit: a clean coil is a more efficient coil, which lowers cooling bills. In-duct air-purification lamps are higher-output and target airborne pathogens; they make more sense in a household with immunocompromised members or recurring respiratory infection. Most homes start with coil sterilization; a few step up to a dual-lamp setup that does both.

Yes, when properly installed. UV-C is harmful to skin and eyes with direct exposure, which is why every install is fully enclosed inside the air handler with a safety interlock that shuts the lamp off if the cabinet is opened. You'll never see UV-C light during normal operation, and the lamp shuts off automatically when service is performed. The only safety rule is don't bypass the interlock when troubleshooting.