The 2008 EPI utilizes the best environmental data available, but remains seriously constrained by a lack of both quality and quantity in data sources. Of a possible 238 countries, the 2008 EPI covers 149, which is up from the 133 covered in the 2006 Pilot EPI. Still, almost 90 countries cannot be included in the EPI because data are not available in one of the six policy categories.
Many critical issues also lack reliable measures. Due to a lack of data, limited country coverage, methodological inconsistencies, or otherwise poor-quality metrics, a number of relevant issues that are considered to be policy relevant and scientifically important are not reflected in the EPI. These gaps include:
- exposure to toxic chemicals;
- exposure to heavy metals;
- several dimensions of ambient air quality;
- waste management (including both household and toxic waste);
- nuclear safety;
- pesticide safety and chemical exposure;
- wetlands loss;
- health of freshwater ecosystems;
- several aspects of greenhouse gas emissions.
It is hoped that future iterations of the EPI will be able to include indicators tracking these issue areas.
