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. Author manuscript; available in PMC: 2015 May 1.
Published in final edited form as: Environ Res. 2014 Apr 5;131:95–103. doi: 10.1016/j.envres.2014.02.017

Fig. 3. Temporal trends of (a) pyrene and (b) Σ8PAHnonvolatile concentrations measured from the central site from 2007 to 2012, stratified by heating season.

Fig. 3

Annual arithmetic mean concentrations of central site PAH levels with 95% confidence interval are presented by heating season; Linear regression modeling was used to test trends over time; The percent change in PAH concentration per year was calculated by 100*[exp(log_βadj)−1] where log_βadj expressed in log-adjusted ng·m−3/year for PAH;; boldface type indicates statistical significance with **p value <0.001.