Here's some news that will have you reaching for the vacuum. According to a new study, crawling babies stir up clouds of "bio gunk" as they move across the floor - a cocktail of dirt, skin cells, bacteria, pollen, and fungal spores, which they then inhale. But don't panic - the implications aren't all bad.
"We are interested in the biological material an infant inhales, especially during their first year of life when they are crawling," said lead researcher Brandon Boor. "Many studies have shown that inhalation exposure to microbes and allergen-carrying particles in that portion of life plays a significant role in both the development of, and protection from, asthma and allergic diseases."
As part of the research, published in the journal Environmental Science & Technology, Boor and his colleagues used a "simplified robotic crawling infant", which they set loose on a carpeted area. The team were interested in just how much biological material these robot bubs "kicked up" while crawling.
"We used state-of-the-art aerosol instrumentation to track the biological particles floating in the air around the infant in real-time, second by second," Boor explained. For comparison, they also looked at what an adult would breathe when walking across the same area - with sobering results. Babies inhale a dose of bio bits four times (per kilogram of body mass) what an adult would.
"Because the infant is so close to the floor, they really create this very concentrated cloud of microbes around themselves as they crawl," says Boor of the findings.
The problem is, babies aren't quite as good as blocking this dust cloud as adults are. "For an adult, a significant portion of the biological particles are removed in the upper respiratory system, in the nostrils and throat," Boor explains. "But for very young children, they more often breathe through their mouths, and a significant fraction is deposited in the lower airways -- the tracheobronchial and pulmonary regions." As a result, the particles then make it into the deepest regions of their lungs.
But why is this a problem? "We care about where they deposit," Boor notes, "because that's where they interact with the lung cells - potential colonisation sites of these bacteria and fungi."
As Boor notes, however, this may not be a bad thing for our growing bubs.
"Exposure to certain bacterial and fungal species can result in the development of asthma, but numerous studies have shown that when an infant is exposed to a very high diversity of microbes, at a high concentration, they can have a lower rate of asthma later in life," he says. "Such exposures act to stimulate and challenge your immune system."
With the research still in its early stages, what do mums and dads need to know?
"One take away from the research is that parents should be aware that their children are exposed to microbes and allergens as they crawl across the carpet," Boor says. "A lot of the research suggests that there can be both adverse effects and protective effects."