We know that we are surrounded by millions of bacteria. And until recently, it had been believed that their appearance was caused by anything or anyone, but not us. However, it is a grave error: each person “adds” up to 37 million bacteria to the environment every hour.
In the 18th century, long before the invention of the first vacuum cleaner, Scottish physician John Hunter said that “dust had destroyed more people than gunpowder.” He was not believed then, but he was 100% right.
Jordan Pecchia, associate professor of environmental engineering at Yale University and the author of the study, says that we live in this “microbial soup”, and it mainly consists of our own micro-organisms. We seldom clean our house, but very often we lead a fairly active life there and do sports, for instance, so the dust that settles on the floor, rises and becomes the main source of the bacteria concentrated in the air that we breathe.
The fact that the surrounding area at home or in the office is full of many microbes is not new. But this study was the first one, with which the researchers have assessed how much the mere presence of human beings influences the quality of indoor air. It took Pecchia and his research group 8 days to analyze the biological particles and measure their number in the university auditorium on the ground floor. The room was vacant for 4 days, and during another four days it hosted regular classes. The doors and the windows would not open throughout the experiment, and the HVAC system was operating normally.
The researchers concluded that while having classes the concentrations of bacteria and fungi of various sizes significantly increased in the classroom. What is important, since the size affects the efficiency of filtrating bacteria from the air, if it exceeds a certain value, the microorganisms stay in the room and circulate in the space. Pecchia also said that, according to his group, approximately 18% of all bacterial emissions were produced by man: of the 15 most common types of bacteria, four were directly related to people, including Propionibacterineae bacteria, often found on human skin.
Pecchia noted that people receive the infections that trigger a variety of diseases mainly from the air they breathe indoors, and not on the street. So, have wet cleaning more often and do not spend all your time indoors. According to the statistics, Americans spend 90% of the time indoors – in their homes and offices.