Environmental pollution is associated with increased risk of psychiatric disorders in the US and Denmark
The county-level environmental quality is assessed by the EQIs designed by the US EPA. (A) A map showing the EPA air quality index across US counties divided into septiles such that Q1 represents the best and Q7 represents the worst air quality regions. The EPA designed the index based on the measurements of 87 pollutants. (B) A map showing the EPA water quality index across counties constructed by the analysis of 80 water quality indicator variables. (C) EPA land quality index map constructed by the analysis of 26 land quality indicator variables. (D) EPA built quality index designed by the analysis of 14 built quality indicators (e.g., amount of vehicular traffic, transit access, and pedestrian safety). (E) A county-level map showing the average number of good weather days that indicated whether at least 4 hours in a diurnal cycle were in a “comfort zone,” defined as a 4-point patch with vertices in temperature and humidity space (temperature [18°C, 27°C, 27 °C, 18 °C] and relative humidity [6.71%, 8.85%, 13.85%, 10%]). (F) A county-level map showing average number of bad weather days that indicated whether at least 4 hours in a diurnal cycle were in an “extremely uncomfortable zone,” defined as <−5 °C or >35 °C. For both the “good weather days” and “bad weather days,” the number per year was averaged over the years during the period 2003–2012. The underlying data for producing these maps can be found in S1 Data. EPA, Environmental Protection Agency; EQI, Environmental Quality Index; NA, not available.