Sure enough, a 1990 study of Sweden’s preschools (which essentially function like day cares) by the National Board of Health and Welfare showed that children who spent five or fewer hours outside per week at day care were sick more often than those who spent six to nine hours outside per week. In 1997, another study that compared traditional preschools with so-called forest schools, where the children spend most of the day outside, confirmed that outdoor kids generally have fewer sick days.
