Research Note 94-6 - California's children: Exposure to air pollution

No. 94-6
April 1994
California Environmental Protection Agency Brief Reports to the Scientific and Technical
Air Resources Board Community

Research Division, John R. Holmes, Ph.D., Chief P.O. Box 2815, Sacramento CA 98512

California's Children:
How and Where They Can Be
Exposed to Air Pollution

Information from this statewide study of the amount of time California's children spend in various activities and locations will be used to develop more accurate estimates of children's exposures to air pollution. Children spend about 85 percent of their time indoors, 11 percent outdoors, and 4 percent in enclosed transit. The time spent in some locations and activities, and the time spent near some pollutant sources, differs markedly among individuals and population subgroups. This study was performed by the Survey Research Center, University of California, Berkeley.

Background: Children constitute California's largest population group sensitive to the toxic effects of air pollution. Reducing their health risk from air pollution requires accurate estimates of exposure to pollutants. Children's activities and the amount of time they spend in specific locations are major determinants of their exposures to air pollutants. Previous studies of children's activities did not obtain specific location information or include large enough populations for reliable estimates. The purpose of this survey was to obtain representative information on where and how California's children spend their time.
Methods: Telephone interviews were conducted with 1200 English speaking Californians 11 years of age and younger. A parent or other primary care provider supplied household information and, for the younger children, activity information. Interviews were conducted during four seasons from Spring 1989 through Winter 1990. Participants completed a verbal recall diary of their activities and locations on the previous day.

Participants also were asked if they used or were near sources of pollution such as cigarettes, solvents, pesticides, paints, and gas appliances. In addition, participants were asked about time spent on different indoor and outdoor play surfaces, which can be sources of pollutant exposure.
Results: Figure 1 shows the average percent of time spent indoors at home, indoors at other locations, outdoors, and in transit. California's children spend by far most of the day indoors, and most of the time spent indoors is spent at home.
This result agrees with estimates from other studies in the U.S. and other industrialized nations. Compared to adults and adolescents in a companion study, children on average spend 68 minutes more per day outdoors, and 42 minutes less per day in transit. Because children spend the majority of their time indoors, estimating their true health risk from air pollution requires a full assessment of indoor exposures, especially exposure at home.

Important differences in activity patterns were found among age groups and between genders. For example, children 0-2 years old spent 104 minutes more per day indoors than those 9-11 years old. Boys 0-2 years old spent more time (115 minutes per day average) near environmental tobacco smoke (ETS) than did older boys (66 minutes per day average), although more girls (41 percent) than boys (35 percent) reported exposure to ETS on their diary day. More boys (35 percent) than girls (29 percent) reported being near gas oven fumes on their diary day. More girls (60 percent) than boys (40 percent) 9-11 years old reported potential exposure to personal care aerosols. These differences are important because some population subgroups such as infants are highly susceptible to the toxic effects of pollutants. Therefore, such differences in activity patterns across population subgroups should be incorporated into exposure calculations in order to provide accurate exposure and risk estimates.
Significance and Application: This is the first major study of children's activity patterns to obtain detailed location data and information about the use or presence of many potential sources of pollutants.

The results confirm the importance of identifying and reducing elevated levels of pollutants indoors. This information on how and where children spend their time is being used to improve estimates of their exposure to pollutants.
Related Projects: A similar ARB-sponsored study of adult and adolescent activity patterns was completed in 1991.

This research was conducted under contract with the Survey Research Center, University of California, Berkeley (ARB Contract No: A-33149). Comments or questions can be directed to the contract manager, Bart Croes, by mail, FAX (916) 322-4357, phone (916) 323-1534, or e-mail: For an index of Research Notes, call (916) 445-0753 or FAX (916) 322-4357.
Copies of the research report upon which this Note is based can be ordered from:
National Technical Information Service
5285 Port Royal Rd
Springfield VA 22161
Request NTIS No. PB94-106903
Title: Study of Children's Activity Patterns.
Authors: James A. Wiley, John P. Robinson, Yu-Teh Cheng, Tom Piazza, Linda Stork, Karen Pladsen.