Can sunlight really kill bacteria in indoor dust

Open the curtains and let the sun come in to kill the ash in the house." This is a common saying, but it seems unreasonable.

However, in a recent study published in the Microbiome, an open access journal in the UK's Nature, scientists have confirmed this long-standing, word-of-mouth folk wisdom – data and models show that Letting the sun shine through the window into the room can really kill the bacteria that live in the dust.

Up to 9,000 bacteria and fungi in household dust

Humans spend most of their time indoors, which makes us inevitably exposed to dust that carries a variety of bacteria and even pathogenic bacteria.

The ecological and evolutionary biology research team at North Carolina State University and the University of Colorado at Boulder has previously discovered that humans not only live with family and friends every day, but also share space with thousands of microbes - only The average amount of microorganisms contained in household dust is 9,000. The average dust in every household in the continental United States contains about 7,000 different types of bacteria and about 2,000 species of fungi.

Dr. Fasimipul of the University of Oregon said that understanding how the characteristics of people's living buildings affect the ecological environment of dust is an important investigation, and it is necessary for people to clearly understand what this relationship has for our health. influences.

In view of this, he and other researchers conducted an analytical comparison experiment and found that an average of 12% of the bacteria in the dark room survived and were able to reproduce. In contrast, only 6.8% of the bacteria in the sun-lit room survive, and only 6.1% of the ultraviolet (UV)-irradiated bacteria still have the ability to reproduce.

Daylight makes indoor microbes similar to outdoor

 Experiments have shown that dust in the dark carries microbial species that are closely related to respiratory diseases, and that these microbes are rarely present in dust exposed to sunlight.。

The researchers produced 11 identical climate-controlled micro-rooms to simulate real-life buildings and then put the dust collected in the homes into these tiny rooms. They treated the windows of the room in three ways so that they could penetrate visible light, ultraviolet light or no light. After 90 days, the research team collected dust from each environment and analyzed its bacterial composition, content and reproductive capacity (vigor).。

The researchers found that compared to dust in the dark, light-derived dust has a smaller proportion of bacteria from human skin, and the proportion of bacteria from outdoor air is higher. This may indicate that daylight makes up the dust of indoor dust, more similar to the bacterial community found outdoors.

Renewing the daylighting program reduces the risk of infection

Dr. Fasimipul, the author of the study, said his latest research supports a centuries-old folk wisdom that sunlight does have the potential to kill microbes on dust particles, but scientists need more research to come. Understand the underlying mechanisms by which sunlight changes the microbial composition of dust. Researchers hope that with further understanding, better lighting schemes can be designed for buildings like schools, offices, hospitals and homes to reduce the risk of infection from dust-borne bacteria.。

The researchers cautioned that the micro-indoor environment used in this analysis was only exposed to a relatively narrow range of light doses. Although the light doses chosen for the experiments and models are similar to those of most buildings, there are still many architectural and geographic features that produce lower or higher light doses, and further research may be needed.

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