Fig. 3

a. Levels of TNFα and b. MIP-2 (pg/ml) after a 24 h exposure of RAW 264.7 mouse macrophages to exhaust gas volume-based doses of PM samples from exhaust of one Euro 2 and four Euro 6 engines. The Euro 2 doses were one tenth of the doses used with Euro 6. Data reported as mean concentration with standard error of the mean (SEM). Asterisks indicate statistically significant differences from the control (Welch’s ANOVA and Dunnett’s t3 test; p < 0.05)