Susceptibility of Populations

MARIE O'NEILL

University of Michigan, Ann Arbor

     Abstract Number: 466
     Last modified: January 13, 2010

Abstract
When considering population health as a whole, one can define susceptibility to air pollution according to a disease state; that is, the population of people with diabetes, cardiovascular disease, or asthma. Other features potentially related to population susceptibility may be defined by demographic or anthropometric characteristics; the elderly, women, babies, children, those within a certain range of body mass index. Genetic susceptibility may also be defined at a population level, more often within a specific epidemiologic cohort where approval to identify gene variants that may relate to a person's response to a given environmental exposure has been granted. Race and ethnicity are used as potential markers of susceptibility, especially in countries where recording of these characteristics is routine, such as the United States. Lifestyle, behaviors, and socio-economic indicators, including smoking, dietary habits, occupation, income, and education are another category. Finally, location of residence, be it with relation to a roadway, pollutant source, defined according to characteristics of the neighborhood in terms of physical features, resources or types and prevalence of individuals living in a particular zone, and/or defined according to some geopolitical feature, from city blocks to nations, can be a way to define populations to evaluate susceptibility.

The array of categories listed above can capture information on a feature of a given person or group that makes them more or less responsive to a given, identical level of pollution exposure. These categories also, however, may be almost wholly unrelated to individual susceptibility, and predominately related to differential levels of exposure (for example, a theoretically homogeneous population whose members differ only by proximity to a road). But often these categories may be related to both exposure and susceptibility. In addition to this complexity, correlations exist among and between the categories that can be used to define susceptibility. Prevalence of diabetes, lack of nutritious food availability, and pollution exposure may all be higher among certain lower-income populations. Thus, it is a scientific challenge to design and conduct research that, according to this conference's central question, 'can be linked to sources the control of which would provide maximal health benefits'.

With the 2005 global update of the World Health Organization air quality guidelines, attempts were made to grapple with the question of how we consider susceptibility in air quality regulation, with chapters on the concept of susceptibility as well as environmental equity. It was concluded that the state of the scientific knowledge with regard to environmental equity was not sufficient to address this concept in generally, globally applicable air quality guidelines. Since that time, some of the gaps in knowledge have been filled, but many remain. This talk will raise the question about to which gaps need to be filled in order to form policies that yield maximal health benefit. I will address areas of inquiry related to susceptibility that have been receiving increasing attention, including air pollution's potential influence on perinatal health and connections between air pollution exposure and land use and urban infrastructure design.