In the case of the exposure to biomass-burning smoke groups, in the comparison of cytokine levels between COPD-BBS and BBES, a significant difference was obtained (p < 0.001) between the cytokine levels of IL-6 (28.3 pg/mL vs. 19.5 pg/mL), IFN-γ (35.6 pg/mL vs. 17.6 pg/mL), IL-4 (28.6 pg/mL vs. 20.2 pg/mL), and IL-5 (48.5 pg/mL vs. 29.4 pg/mL). Here, IL4 is linked to chronic obstructive pulmonary disease.