ABSTRACT
In the USA and Canada, people spend about 90% of their life indoors. Canadians spend less time outdoors in winter and less time indoors in summer than their US counterparts. In all age groups, the majority of the time is spent indoors at home. The distribution of time for adults and children <11 years is broadly similar except the latter spend more time in transit. Youths between 11 and 17 years spend less time at home than adults and more at school/work and other indoor locations (e.g., shopping malls, indoor recreation facilities) (1). In seven cities in Europe, the pattern is similar, but there is much more variation in the percentage of the day spent indoors in locations other than home, school, or work (2). However, cities in southern Europe are not represented in this study, so the picture is incomplete. A study of 4-to 6-year-old children in Japan reported similar data to the US or Canadian study above (3). In Hong Kong, residents spent 86% of their time indoors, with the distribution also being similar to North America, except that a greater percentage of time was spent in transit (4). Regardless, in the past three decades, this has focused on the built environment as a determinant of health.
