Maybe it’s time to rethink that broom.
Recent research indicates that introducing more dirt into your home could actually benefit your child’s asthma and allergies, particularly in urban environments.
But it’s not just about the dust accumulating. It seems you need to connect with the outdoors more.
In this study, Finnish researchers collected soil from under two feet of snow in a forest, carefully sifting and freezing it to keep the tiny organisms safe.
After obtaining this soil, they pressed about a tablespoon of it into a flat-woven rug sold in stores, embedding it deeply within the fibers.
Next, they enlisted six homes in eastern Finland, which varied from eight-story apartments to single-family houses. Some had pets, while others did not, and each home had between two to five residents.
Five of these homes received a “forest rug” to place just inside their front doors, while the sixth home served as a control.
The main goal was to determine whether these soil-infused rugs could alter a home’s microbiome—the invisible collection of bacteria and fungi found indoors.
Since young children spend so much time at home, the microorganisms they’re exposed to are believed to be significant in training their immune systems.
Previous research has shown that urban housing often has less environmental microbial diversity than rural settings, which may correlate with higher instances of asthma and allergies in city-dwelling children.
The researchers hypothesized that having these rugs near the front door would allow particles to be kicked up, potentially enhancing the home’s microbiome.
They rotated the rugs with fresh soil every four weeks over a two-month period. Dust samples were collected initially, then every two weeks, and continued to be monitored for six weeks after the final rug was placed.
Samples were gathered at two heights: 12 inches (near infants) and 5 feet (closer to adults).
Analyzing the bacterial and fungal DNA from the dust, they tracked the indoor microbiome’s reaction to the forest soil.
Over a 20-week period, observable changes took place.
As microbiologist Martin Taubel noted, “When we applied forest soil on the rug, there was a clear increase in bacteria associated with forest soil in the air,” according to a press release.
“The effect was most pronounced at the infant breathing level during the initial two weeks, with signals also detected in other parts of the house.”
However, after about four weeks, the bacterial levels began to revert to baseline, indicating that regular replenishment of forest soils is needed to maintain a diverse microbiome.
The most significant changes were found in an eighth-floor apartment housing one adult and a part-time child, with no pets and full mechanical ventilation.
In that apartment, forest bacteria near the infant breathing level increased nearly 10 percent after just one addition of soil compared to control homes.
Although this study didn’t measure direct health outcomes, it showed a rise in FaRMI, a marker previously associated with a decreased risk of asthma in kids.
“It’s encouraging that such a straightforward and affordable intervention could elevate signs of microbial exposure linked to lower asthma risk in urban settings,” stated Pilkka Kirjavainen, a senior author of the study.
She added, “The next step is to find out if this kind of intervention actually produces the health benefits we anticipate.”
Still, there are some limitations. This was a small study focused solely on eastern Finland, so broader research in different environments is necessary to validate these findings.
If these results hold true, they could have implications here in the United States.
Asthma is the most prevalent chronic condition among children, impacting around 5 million kids across the nation.
The ramifications are significant, as poorly controlled asthma leads to more than 10 million missed school days, around 74,000 hospitalizations, and nearly 767,000 emergency room visits each year, according to the National Heart, Lung, and Blood Institute.
