For summer , pearson's correlation coefficients between both indoor PM 2.5 and BC concentrations with incresing distance from industry were -0.35 for BC and -0.30 for PM2.5 For the winter, correlations between PM2.5 and BC concentrations with increasing distance from industry were -0.31 tor BC and-0.10 for PM2.5 . Outdoor estimates from LUR most strongly with BC during winter , suggesting industrial influence consistent with previous work