study summary / 012

Can biodiverse daycare yards influence immune markers?

A Finnish intervention links changes in yard biodiversity with microbiota and immune-regulation measures.

A playground provides contact with living material as well as space for movement. Roslund and colleagues examined a biodiversity intervention in daycare yards.

The study

75 children aged 3-5 attended 10 Finnish daycare centers: 36 in four intervention centers, 16 in three standard centers and 23 in three nature-oriented centers. Forest floor, sod, planting boxes and peat were introduced for 28 days. Children were not individually randomized.

The findings

The intervention group’s IL-10:IL-17A ratio rose from 0.86 to 1.15, a statistically significant change; comparison groups showed no significant increase. Skin Gammaproteobacterial diversity was associated with changes in TGF-beta1 and regulatory T-cell measures. These are specific immune-regulation findings, not a general 'immune boost'.

Architectural interpretation

Biodiversity can be studied as part of the material design of outdoor learning environments. The connection to architecture concerns exposure opportunities, not an established treatment.

Limits and conclusion

There were few centers, follow-up was brief and sample availability differed by outcome. Home exposures could also matter. The study did not demonstrate disease prevention or brain changes.