Inhalation intake of ambient air pollution in California's South Coast Air Basin

Julian D. Marshall, Patrick W. Granvold, Abigail S. Hoats, Thomas E. McKone, Elizabeth Deakin, William W Nazaroff

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Reliable estimates of inhalation intake of air pollution and its distribution among a specified population are important for environmental epidemiology, health risk assessment, urban planning, and environmental policy. We computed distributional characteristics of the inhalation intake of five pollutants for a group of ∼25,000 people (∼29,000 person-days) living in California's South Coast Air Basin. Our approach incorporates four main inputs: temporally resolved information about people's location (latitude and longitude), microenvironment, and activity level; temporally and spatially explicit model determinations of ambient concentrations; stochastically determined microenvironmental adjustment factors relating the exposure concentration to the ambient concentration; and, age-, gender-, and activity-specific breathing rates. Our study is restricted to pollutants of outdoor origin, i.e. it does not incorporate intake in a microenvironment from direct emissions into that microenvironment. Median estimated inhalation intake rates (μg d-1) are 53 for benzene, 5.1 for 1,3-butadiene, 8.7×10-4 for hexavalent chromium in fine particulate matter (Cr-PM2.5), 30 for diesel fine particulate matter (DPM2.5), and 68 for ozone. For the four primary pollutants studied, estimated median intake rates are higher for non-whites and for individuals in low-income households than for the population as a whole. For ozone, a secondary pollutant, the reverse is true. Accounting for microenvironmental adjustment factors, population mobility and temporal correlations between pollutant concentrations and breathing rates affects the estimated inhalation intake by 40% on average. The approach presented here could be extended to quantify the impact on intakes and intake distributions of proposed changes in emissions, air quality, and urban infrastructure.

Original languageEnglish (US)
Pages (from-to)4381-4392
Number of pages12
JournalAtmospheric Environment
Issue number23
StatePublished - Jul 2006

Bibliographical note

Funding Information:
Funding for this work was provided by the University of California Transportation Center, the University of California Toxic Substances Research & Teaching Fellowship, Cooperative Agreement Number U50/CCU922409-01 from the US Centers for Disease Control and Prevention, the US Environmental Protection Agency National Exposure Research Laboratory through Interagency Agreement No. DW-988-38190-01-0, and Lawrence Berkeley National Laboratory operated for the US Department of Energy under Contract Grant no. DE-AC02-05CH11231. The authors thank Paul Burke and Pablo Gutierrez at the Southern California Association of Governments (Los Angeles, California) for providing SCAG transportation survey data, and the air-pollution modeling group at Environ Corporation (Novato, California) for providing CAMx air dispersion model results.


  • Diesel particulate matter
  • Environmental justice
  • Exposure analysis
  • Geographic information system (GIS)
  • Mobility
  • Ozone


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