Wild-type littermates and Rev-erbα KO mice were exposed to room air, 10 days (acute) or 30 days (sub-chronic) of CS. Total cell counts per ml in BAL, macrophages, and neutrophils in WT or REV-ERBa KO mice exposed to room air, (A) acute CS (10 days) or (B) sub-chronic CS (30 days). In (A and B) data are presented as total cell counts per ml in BAL fluid while in (B) macrophage and neutrophil levels are presented as a percentage of total cells. For 10 days CS exposure, the number of total cells in BALF was counted in at least 500 cells stained with Diff Quik on a hemocytometer. For one month CS exposure, the cell counts were determined using a flow cytometer (See Methods). In A and B, data are shown as mean ± SEM, n=4–6 per group for one month Air and CS exposures, and n=3–8 per group except for Rev-erbα KO and Air n=2 per group for 10 days. *P<0.05 and ***P<0.001 vs WT-Air or Rev-erbα KO-Air.