Additional file 2: Figure S2. of Air toxics and early childhood acute lymphocytic leukemia in Texas, a population based case control study

POM Ambient Air Levels in Texas by NATA Year. POM Ambient Air Levels in Texas by NATA Year. Map illustrating spatial distribution of ambient air POM concentrations for all census tracts in Texas by NATA years included in our study. Figure S2: POM Ambient Air Levels in Texas by NATA year. Exposure groups: Low (0–24th percentile); Medium (25–49th percentile); Medium-High (50–74th percentile); High (75–100th percentile) based on distribution among controls. Boundary lines for census tracts were removed for the Medium, Medium-High, and High groups and graduated color used instead to improve readability of maps and spatial distribution of exposure quartiles. (PDF 1816 kb)