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We spent 90% time indoors! Who said it?
November 26, 2020

We spent 90% time indoors! Who said it?

The very much-quoted statistics: 90% time indoors!

Surprisingly there were many studies performed at the 20th-century gathering human activity patterns and human exposure data. And one marginal study was published in 2001 that was based on the idea of time-budget and money in America, i.e. a time-budget for a person which has 24-hour of different activities and one wants to quantify or “money-fy” it.

The key figure: 87% indoors!

The statistics are clear: in a building (68.7%), outdoors (7.6%), in the car (5.5%), in the office-factory (5.4%), in the restaurant-bar (1.8%), and other indoor locations (11%).

Are we indoor people?

In the stone age (about 2.6 million years ago until about 3,300 B.C),  the results would be probably completely the opposite. But now we live in the modern world, which means more time indoors, i.e. 90% time indoors.

Another researcher W.R. Ott basically suggested that a large amount of time spent indoors is a fundamental characteristic of the human species. “The finding that emerges is that we are basically an indoor species,” said W.R. Ott, the researcher, the statement from the 1980s. “In a modern society, total time outdoors is the most insignificant part of the day, often so small that it barely shows up in the total.”

But that may be slowly changing… And perhaps after some more years or decades, maybe even centuries, people will again live differently – perhaps more outdoors or even in the space! Hopefully, with good air!

Abstract – shortened!

Because human activities impact the timing, location, and degree of pollutant exposure, they play a key role in explaining exposure variation. The largest of these recent efforts is the National Human Activity Pattern Survey (NHAPS), a two-year probability-based telephone survey (n = 9,386) of exposure-related human activities in the United States sponsored by the U.S. Environmental Protection Agency (EPA).

NHAPS was conducted on a virtually daily basis from late September 1992 through September 1994 by the University of Maryland’s Survey Research Center using a computer-assisted telephone interview instrument (CATI) to collect 24-hour retrospective diaries and answers to several personal and exposure-related questions from each respondent. Between 340 and 1713 respondents of all ages were interviewed in each of the 10 EPA regions across the 48 contiguous states.

NHAPS respondents reported spending an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles. These proportions are fairly constant across the various regions of the United States and Canada and for the California population between the late 1980s when the California Air Resources Board sponsored a state-wide activity pattern study, and the mid-1990’s when NHAPS was conducted.

Download the paper!

Download the paper at The National Human Activity Pattern Survey (NHAPS): A Resource for Assessing Exposure to Environmental Pollutants, by Neil E. Klepeis and others, and published by the Lawrence Berkeley National Laboratory in 2001, founded by the U.S. Environmental Protection Agency (EPA).

Read more about indoor!