When babies crawl, their movement across floors, especially carpeted surfaces, kicks up high levels of dirt, skin cells, bacteria, pollen, and fungal spores, a new study has found. The infants inhale a dose of bio bits in their lungs that is four times what an adult would breathe walking across the same floor.

Researchers are interested in the biological material an infant inhales, especially during their first year of life when they are crawling.  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 babies roll, slide and crawl on the floor, their movements stir up more particulates into the air, and their mouths and nostrils are much closer to the floor where the concentrations are greater. This is countered somewhat by the fact that babies tend to move in much shorter bursts of activity than do older children or adults.

To study just how much of the floor debris babies breathe, the research team built a robotic crawling baby and tested it crawling on actual carpet samples they had removed from homes. Then the researchers measured and analyzed the particulates in the breathing zone.

Researchers 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. The instrument uses lasers to cause biological material to fluoresce.

Most bacterial cells, fungal spores, and pollen particles are fluorescent, so they can be reliably distinguished from non-biological material in the air. They also worked with a microbiology group which conducted DNA-based analysis of the microbes, they collected onto filters.

The researchers found that a concentrated cloud of resuspended particles forms around the Pig-Pen wannabes, and that the concentrations around them can be as much as 20 times greater than the levels of material higher in the room. Moreover, infants' bodies are not as good at blocking this dust storm.

For an adult, a significant portion of the biological particles are removed in the upper respiratory system, in the nostrils and throat. But for very young children, they more often breathe through their mouths, and a significant fraction is deposited in the lower airways. The particles make it to the deepest regions of their lungs.

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. Such exposures act to stimulate and challenge your immune system.

The research established new methods for infant microbial exposure assessment, much remains to be discovered. Researchers hope to continue to work with microbiologists and immunologists to better understand the role of indoor air microbes and allergens on early-childhood health.