Figure 1
From: Lifestyle practices that reduce seasonal PM2.5 exposure and their impact on COPD
Mean PM2.5 concentrations by season. (A) Outdoor and indoor PM2.5 concentrations by season. (B) Indoor PM2.5 concentration compared with the outdoor PM2.5 concentration by season. The overall outdoor PM2.5 concentration was higher than the indoor PM2.5 concentration in all seasons except summer. The difference between indoor and outdoor PM2.5 concentrations was greatest in winter.
