Lung Function Decline after 24 Weeks of Moxa Smoke Exposure in Rats

OBJECTIVE: Moxibustion is a complementary therapy that has been used for thousands of years. Burning moxa produces smoke and inhalable particulates. Recent research has indicated that smoke inhalation is associated with negative lung effects. This study aimed to evaluate the lung function of rats after moxa smoke exposure at different concentrations. METHODS: Using a randomised block experiment design, 28 male Wistar rats were randomly divided into three moxa smoke groups (opacity) (n=7): low concentration (27.45 mg/m(3)), medium concentration (168.76 mg/m(3)), and high concentration (384.67 mg/m(3)) with a control group. Rats in the moxa smoke groups were exposed in an automatic dynamic exposure device separately with different concentrations for 20 min/d, 6d/week, for 24 weeks. Rats in the control group were exposed in the same space without moxa smoke. Lung function was evaluated by the AniRes 2005 animal pulmonary function analysing system. Statistical Product and Service Solutions 18.0 software was used for data analysis. RESULTS: In the study, no deaths were found in any group. There was no difference of forced expiratory volume in one second/forced vital capacity percentage (FEV1/FVC%), inspiratory resistance (Ri), and expiratory resistance (Re) among each group after 24 weeks of moxa smoke exposure (P>0.05). Compared with the control group (0.33 ml/cmH(2)0), dynamic compliance (Cdyn) was reduced in the medium (0.29 ml/cmH(2)0) and high (0.25 ml/cmH(2)0) concentration groups (P<0.05); however, Cdyn in the low concentration group (0.29 ml/cmH(2)0) was not significantly affected. CONCLUSION: Moxa smoke exposure at low concentrations did not affect the rat's lung function. Moxa smoke of medium and high concentrations destroyed the lung function represented by decreased Cdyn. However, moxa smoke of low concentrations (27.45 mg/m(3)) is much higher than the concentration in a regular moxibustion clinic (3.54 mg/m(3)). Moxa smoke at higher concentrations might destroy the lung function. The safety evaluation of moxa smoke requires further research.