Construction of an environmental quality index for public health research (39 page pdf, Lynne C Messer, Jyotsna S Jagai, Kristen M Rappazzo, Danelle T Lobdell, Environmental Health, May 22, 2014) Today we review research aimed at developing a more accurate index of environmental quality than traditional indices used to select the greenest or healthiest or highest environmental quality of a place in the world. The older indices tend to use spot observations of a single indicator to represent an area or ambient value, and they tend not to consider a combination of several variables to evaluate land, air, water, built environment and socio-demographic conditions. An example of the latter is the difference in crime rates between urban and rural areas where the latter would feel safer and have a higher environmental quality than the former, all other variables constant. On the other hand, some urban areas have a better built environment (more bike and pedestrian paths, etc) than some rural areas where highway deaths are higher.
The proposed Environmental Quality Index (or EQI) uses 22 performance indicators to estimate environmental sustainability for all the counties in the USA. The resulting indices were weighted so that there were an equal number of regions at the low end as well as at the high end of the index scale. As the authors note, the EQI represents only the outdoor environment and indoor conditions may, on occasion, be more important from a health point of view or need to estimated from a different set of variables.
“The empirical characterization of environmental conditions, however, is challenging because the non-residential ambient environment comprises an almost uncountable array of complex mixtures, which are difficult to quantify simultaneously… rarely, if ever, are multiple environmental domains combined, even though we know humans are exposed to these multiple environmental domains simultaneously”
“Here we describe a method of constructing an environmental quality index (EQI) representing multiple domains of the non-residential ambient environment, including the air, water, land, built and sociodemographic domains.”
“We developed an Environmental Quality Index for all counties in the United States incorporating data for five environmental domains: air, water, land, built, and sociodemographic. For each environmental domain, variables were constructed to represent exposures within that domain; indices for each domain and for environmental quality as a whole were developed by stratifying by rural–urban continuum codes. Variable loadings varied by domain and rural–urban designation, suggesting that environmental quality is driven by different domains in rural and urban areas.”
“The EQI is focused mostly on the outside environment, which may not be the most relevant exposure in relation to human health and disease.”