With homes being built more energy efficient and tighter to the outside air, conditions inside are continuously under threat of toxic microbial growth. Part of this is because the outdoor space has a larger volume of air for toxins to be diluted and outdoor benign fungi and bacteria also keep down growth of toxin forming fungi. For example, an indoor water leak onto a basement carpet with under padding or a leak behind a wall with wood, insulation and dry wall are both good conditions for toxic mold and bacterial growth.
Our indoor air is constantly being conditioned by our A/C conditioning unit (s). Despite air filters on the air intake side of the system, the HVAC units can still become dirty. Air conditioning coils get cold while the A/C unit is running, which creates an area of moisture on the coils. Dirt and debris landing on the coils can then lead to microbial growth. Continued microbial growth can then lead to aerosolized toxin fragments from fungi. Our own HVAC units can become a BIOWEAPON in the right conditions if they are not cleaned and maintained. Cold based molds which can produce mycotoxins like to grow in these conditions. Just as we maintain our cars, we should have routine maintenance on our HVAC system.
If the HVAC unit is found to have a heavy burden of microbial growth, or if the house has an elevated ERMI (mold dna per testing) with occupants who have inflammatory response syndrome/CIRS, the HVAC should be cleaned after the house is remediate of water damaged items and live microbial growth. HVAC contractors are required to have certification, but how they clean the unit can be important. Cleaning may either consist of rotating brushes, cleaning solvents and disinfects, and/or vacuum suction. Chemically sensitive individuals need to inform the company of their sensitivity, as they may be fogging with quaternary ammonium compounds which can make sensitive individuals ill. One safe way in sensitive individuals, is to clean the ducts by using negative air/vacuum containment. Larger companies will often hook part of the duct outlet to a vacuum device outside the home, often in their work truck. They then blow out debris at each vent toward the vacuum end. They should be sealing and closing the vents that are not being used so not to aerosolize toxins throughout the house. After the HVAC is cleaned and flushed, then the house should undergo fine particle remediation, which may include aerosolver fogging and wipe down of all horizontal surfaces with a damp cloth. Also though, the HVAC coils will need to be inspected and cleaned if needed.
This is the inside of an HVAC cabinet near the coils with someone who has CIRS. Look at the microbial colonies that grew in this humid environment. Many homes have HVAC units which look like this if they are not maintained.
The picture below shows my air conditioning coils on my attic HVAC unit, which is inspected by my HVAC company every 6 months. This picture is from last weeks maintenance check. The coils had a slight amount of microbial growth which may have amplified in the upcoming summer season if this was not preventively cleaned. With a few minutes of cleaning, the coils looked new.
Many times HVAC companies will recommend a UV light to help prevent microbial growth on the coils. Just understand that this may not prevent the antimicrobial growth since microbes are flying by the UV light at rates too fast for the antimicrobial activity to occur. Current consensus recommends doing UV light combined with a PCO technology. PCO or photocatalytic oxidation throws off an oxidant cloud which will helps neutralize microbes and toxins. Air Oasis Nano and several other companies make technology with UV/PCO which can be installed in your HVAC unit and help keep them free of microbes and toxins. Just ask your HVAC company which UV/PCO unit they recommend and if they suggest only a UV light, then ask them to look into PCO technology. Understand though that installing a UV/PCO unit may cost an extra $500-1000 and you will still need routine maintenance. From what we now know, it appears units with an installed UV/PCO can be inspected less frequently, so you likely can get away with every 12 months of HVAC routine maintenance since. For handy individuals and especially for households who have individuals with CIRS, it’s fairly easy to open up the HVAC air handler cabinet by removing 4 screws and inspecting the coils. You can also order an Air Oasis Nano and install them yourself. Installing mine only took 20 minutes which required drilling a 3.5 inch hole with a large drill accessory from home depot, inserting the Nano into the hole, a few screws to secure it in place, then plugging the unit into a power outlet. Of note, I decided to leave the attic HVAC handler alone to do my own self assessment to see if UV/PCO technology really worked. The unit in the attic always has a light amount of microbial growth on the coils. The HVAC unit with the Nano always appears clean except for some dust. This is a pic of the installed Nano.
-Find a HVAC company and ask them to come inspect your system, which includes checking the cleanliness of the ducts and the air conditioning coil. They will also check for water leaks and condensation round the unit.
-Sign up for a routine maintenance plan which costs a few hundred dollars per year or do the filter change/coil inspection yourself.
-Most HVAC unit panels have 4 screws on the outside, so it only takes a few minutes to open the unit, self inspect, and clean the coils if your handy and have the time.
-Change the air filters every 3-4 months.
-Use the highest MERV rating filter your system can handle. Ask your HVAC company what filter your unit can handle if you are unsure
Yours in health