A visitor to your home will sense them more quickly than you. Prolonged exposure makes them invisible to you. You will often notice them when you first arrive home. Odors are part your body’s self-defense warning system.
Dogs, cats, hamsters, carpet, cooking, people all give off cells, hair, fur, gasses, VOC’s that are detectable to the human nose. To some people it’s just a smell. To some it can trigger an allergic, histamine reaction. I’m not an expert in allergies but my work involves dealing with the conditions related to humidity and air filtration. Controlling relative humidity in South Alabama is a larger part of maintaining comfort than in most other non-coastal locales. Mold grows in humid conditions so that makes air conditioning technicians a resource for controlling airborne mold inside the home. We apply and repair the equipment that controls humidity, and filters particulates from the air.
Newer houses are constructed to leak less air than older houses. This trend started earlier in the North as heating homes uses quite a bit of fuel. Energy efficiency in air conditioned homes moved this practice to the southern United States in the 1970’s. I mention this to point out that you live in a different structure from your parents. The home you grew up in during the 1950’s, 60’s, 70’s and 80’s exchanged air more freely with the outside which reduced the concentration of various pathogens and chemicals. Tightening up homes creates a different indoor environment but ventilation practices have not kept pace with these changes.
Ventilation – Kitchen range hoods carry steam and aerosol oils from cooking directly to the outside. The best way to keep cooling odors reduced is the kitchen range hood. Open the cabinet above your range. If there is no duct visible you probably don’t have a vented range.
Use bath exhaust fans after showering until the mirrors clear and then 15 minutes longer. Consider removing the inexpensive fan that came with your home and replacing it with a larger model. Quiet models with heaters for winter use save energy by heating the bath while you are damp from bathing. Removing excess humidity reduces the moisture necessary for mold spore propagation.
Air Filters – There are several options available here. Even the least expensive is effective if they are changed regularly. How often depends on your home: More often in summer, less often in winter. Looking at them is a good indicator of the correct interval.
Extended surface filters are a good option but are not always commonly available. The advantage is that they offer less resistance to airflow while still filtering a very small particle. People that use them properly gain the advantage of clean equipment and extended life. The dirt that collects on the cooling coil accelerates corrosion that leads to refrigerant leaks and the moldy odor noticed when the air conditioner comes on. Customers sensitive to that odor usually call us asking to have the ductwork cleaned. Here is a photo from a few weeks ago.
Dirty indoor Cooling Coil
Click on the image and you can see at the bottom where I cleaned a small section with a wire brush. The rest of that is mold living on the coil. It is more common to see this than not. Once mold gets started, it maintains itself very easily and is difficult for you to remove.
Carpet – Carpet can be cleaned. The pad under a carpet cannot be cleaned. Dirt from outside sifts through the carpet and pad and forms a silt-like layer on the underlaying floor. If you watch carpet being replaced, look at the fine powder on the floor under the pad. 3 month air filters last 3 months in a carpeted home, 6 weeks or less with wood or tile (2 to 4 weeks with pets). Air filters last longer in a carpeted house because carpet catches a large amount of dirt. Carpet in a home collects years worth of debris from shoes, skin cells from humans, spills, dust mites.
The dirt under the pad can have dust mites which can trigger allergies. It also has bacteria in abundance; not ‘can have’ but ‘has’. Interior relative humidity above 65% provides an ideal environment for mold. Mold propagates well in dark, damp places and bacteria is a food-source for mold.
A normally functioning central air conditioner will maintain right about 55% relative humidity (rh) many months of the year . In the spring and fall during mild weather you will see 60 to 80% rh for extended periods.
If you are having allergic reactions and you have carpet, consider hard-surface flooring as an alternative.
Dirty sock syndrome – This condition mostly affects heat pump indoor units. The aluminum fin of the indoor coil becomes etched chemically in a short time of operation forming microscopic fissures in the surface of the fin. A cooling coil in a typical home has up to 300 square feet of aluminum fin surface. Mold growing on these 300 square feet gives off a moldy, dirty sock odor at the first start-up in the winter. The wet mold in the fissure is heated by the heat pump operation and gives off a very strong repugnant odor for a day or so until the heat kills it. In the fall we routinely switch between cool and heat which generates a new crop of mold and odor.
Containment – Laundry hampers, compost pails and closed garbage cans can prevent odors from building up in your home. Damp clothes, food scraps and household garbage emit products of decomposition that linger and accumulate in textiles in your home. Containing them reduces the odors.
Pets – Control of pet odors varies with the pet. In my life I have had hamsters, rats, birds, cats, dogs, iguanas and probably some that I forget. I won’t go into the varied types of odors and requirements of keeping down pet odors. Litter boxes, cages, and the pets themselves all require different measures. Assuming that each pet is cared for and their quarters are clean, there are still odors that can be readily detected by visitors. For this there is a magic bullet(s). Oxidizers. That annoying guy on the Oxiclean commercials is selling a product that uses this principle in cleaning fabrics. It can also be used to clean air.
There are devices available that generate oxidizers, mainly ozone and hydrogen peroxide. These are molecules that are dispersed into the living space from devices inside the return or supply duct. These devices consume less than 25 watts of electricity to power ultra-violet lamps.
Ozone and hydrogen peroxide react with mold and viruses in the ductwork and in the household environment killing them and/or stopping their propagation. Ozone (O³) is generated with a less expensive device than hydrogen peroxide (H²O²). Peroxides have a less noticeable odor than ozone. Also, there are limits to the amount of ozone you want in your home as it can irritate lung tissue. Peroxide generators are surprising in their effectiveness in eliminating odors inside the home. Installed cost of a peroxide generator is about $1,000.00 and they require an element replacement every 3 years at a cost of about $350.00. This gives an annualized cost of operation over a 15 year period of $165 per year or 44¢ per day. It is a luxury but it is a nice luxury. It can really make your home smell fresh with no masking odor. Also there is a reduction in allergens which can reduce histamine reactions.
Other points in your home to review are mainly structural in nature. Some structural issues are air conditioning related because of the temperature of the building materials and the humidity of the outside air. I will go other some of these items in future articles.