Air conditioning seems to be your best friend in these last hot summer days. But those refreshingly cold gusts of air can also release microbes in your home or office – and potentially make you sick.
With a grant from the Sloan Foundation, Prof. Jordan Peccia’s Chemical and Environmental Engineering Laboratory studies the insides of air conditioning systems and the types of bacteria and fungi that promote them. The idea study was inspired in part by research that showed high levels of illness in people who work and live in air-conditioned buildings. The symptoms reported are mostly minor, such as: B. the tightening of the chest and dry cough. However, exposure to air conditioning has also been linked to Legionnaires’ disease.
In the past few decades, the rise of air conditioning has been rapid. In 1965, AC devices were only found in about 10% of homes in the United States. Today they have about 85% of the houses and 95% of the office buildings. The presence of air conditioning in office buildings has been linked to 30-200% increases in respiratory and other health systems compared to naturally ventilated offices. However, our knowledge of the microbes that grow on AC coils has not kept pace. Previous studies have identified the potential for microbial growth on AC coils and their deleterious effects on humans. However, there is still a lot to learn about the microbiology in AC devices.
“We don’t know why or how, but previous work has shown that using UV light to remove the microbes from the coils of the AC system makes people feel better,” Peccia said.
Researchers from the University of Toronto and the California Department of Health are also working on the two-year study, which will collect microbe samples from numerous air conditioning systems in the northeastern United States (including buildings on Yale’s West Campus) and Sacramento, CA. Using genetic methods, they take stock of all the microorganisms they find in the units. They determine which factors (e.g. outside air temperature or humidity or AC coil temperature, etc.) affect the growth of bacteria and fungi in AC units. Then they measure the speed at which these microorganisms are dispersed in the air.
“We’re going to search the coils of these large systems to see what is growing there – what kind of fungi, what kind of bacteria are growing on those coils.” he said. “If you think about it, air conditioning coils are damp, cold places. Anywhere there is water in a building, we usually find bacterial and fungal growth. There are things in them that can spread throughout the building.”
Peccia believes the air conditioners create unique environments for microbes. “The cold, alternating wet and dry conditions in AC devices create a unique environment and are likely to encourage the growth of a narrow range of microbes,” he said. “Once we have identified these unique microbes, we will look for them in dust and air samples throughout the building to find out how much air conditioning really affects microbial exposure in a building.”
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