Air conditioners can save lives and keep us comfortable on sizzling days. But they can also bring health risks – namely that related to fungus.
This was emphasized again last week, when the manufacturer Midea voluntarily Remembered around 1.7 million air conditioners Due to a design error that encouraged fungal growth.
Although that error made fungal growth more likely, every air conditioner can be moldy, no matter how well designed it is. Fortunately, there are ways to reduce the risk.
Why are air conditioners moldy?
It’s simple: moisture.
Whether you have a window unit or central air, the basic process is the same. Air conditioners work by repeatedly converting a coolant of gas into liquid and back to gas. While the coolant evaporates, the heat from the air absorbs through a cold component called the evaporator coil. A fan blows over the coil and pushes cool air into the house, while hot air is withdrawn to the outside and the coolant is condensed back in liquid to restart the process.
While warm air cools, it produces condensation. Consider the way water droplets form on the outside of a glass when you pour cold water into it. For air conditioners, a drain pan collects this water, and well -designed systems can flow out rather than staying still. But those systems can work out, or just be imperfect.
That means that moisture can be within your air conditioner for a longer period of time, which leads to fungal growth, said Mark Mendell, a former research specialist in air pollution at the California Department of Public Health and former staff scientist and epidemiologist at the Lawrence Berkeley National Laboratory.
Dr. Mendell’s research was aimed at the health effects of fungus in indoor air, not specifically on air conditioners. But the process he described can occur in any type of air conditioning system, he said. “There will collect water that is not really good, and maybe it is dirty. And the air blows over this in your house.”
What are the health risks?
Despite the omnipresence of air conditioners and their tendency to become moldy, there is not much scientific literature about the health effects.
One of the few of such studies, Published in 2003Discovered that when the cooling and drain pans within office air conditioning systems were irradiated with ultraviolet light to kill bacteria and fungi, employees reported less respiratory and other symptoms.
For the most part, however, we have to extrapolate from broader research that has investigated the health effects of moisture and fungus in indoor environments, but not specifically in air conditioning systems.
An overview of that research Published in 2011 concluded that exposure to moisture and fungus is associated with exacerbations of asthma, coughing, squeaky breathing and symptoms of the upper respiratory tract, but it did not notice that fungus was the cause. Another review Published in 2015 Sufficient evidence found to say that moisture and fungus were a reason for aggravating asthma in children.
Researchers have discovered that these types of symptoms occur more often in buildings where people can see or smell fungus, Dr. Mendell, but studies have not proven connections between symptoms and measurements of specific fungus levels. It is possible that researchers have not measured the right types of fungi, or that other factors are involved.
“It seems likely that some moist microbiological exposures will prove to be the cause of the health problems, but we just don’t know for sure,” said Dr. Mendell.
What precautions can you take?
Basic air conditioner maintenance, such as regular cleaning filters, can help prevent fungal growth. Many window units have a light that indicates when cleaning is needed, but once or twice a month is a good rule of thumb.
Whether you have window units or central air, master the humidity in your home, with a dehumidifier if necessary, is also useful. And it is a good idea to keep your house clean in general, because it reduces the amount of dust, a food source for fungus that can enter the air conditioner. Turning an air purifier can remove both dust and fungal traces.
But these precautions are not a panacea. You must periodically inspect your air conditioner, especially if it is not used for a longer period, such as in winter.
Mold can be visible around the ventilation openings and a flashlight can help you see deeper. If you are ready, you can also disassemble a window unit according to the instructions in the manual, to better inspect the coils and the drain pan and, if necessary, to clean.
Detailed cleaning instructions for both window and central air conditioning units can be found here.
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