Abstract: [Objective]Taking forest absorption of smoke and dust as an example, this study empirically examined the effects of smoke and dust on the related diseases of residents' respiratory system, thus quantitatively analyzed of the relationship between air pollution and public health.[Method]A literature review and qualitative analysis were conducted to explore respiratory-related diseases caused by air pollution, forest affect human health by reducing air pollutants. In addition, using panel data from China, a quantitative analysis was carried out to estimate the effects on public health of dust by OLS, panel model, 3SLS. Especially, using 3SLS method to overcome endogenous problem caused by emissions of particulate matter, thus more accurately evaluate the negative impact of environmental pollution on public health, and effectively explain the regional heterogeneity. Finally, using different emissions as an instrument to estimate the robustness of the result, ensure the reliability of conclusions.[Result] 1) OLS estimates show that the impact on public health of dust is very significant:as the smoke and dust emissions increase 1%,the number of people dying from lung cancer and respiratory diseases corresponding increase 0.568% and 0.488%,respectively. 2) Random effect model (RE) show that lung cancer deaths caused by the smoke and dust decreased dramatically, and is significantly positive with deaths from respiratory diseases at 10% level. As the smoke and dust emissions increase 1%, the number of deaths from lung cancer and respiratory diseases correspondingly increase 0.207% and 0.467%, respectively.3) Using the area of pests and diseases as an instrument of forest area, endogeneity smoke and dust emissions are solved. Based on 3SLS, this study shows that forest area will significantly affect the level of smoke and dust emission,as forest area increase by 1%, the smoke and dust emissions reduce by 0.884% approximately. Whereas the smoke and dust emissions increase by 1%, the number of people dying from lung cancer and respiratory diseases will increase by 0.777% and 0.704%, respectively.These value are higher than those obtained by OLS, and random effect model, which shows that the last two method underestimate the impacts of air pollution on public health. 4) Other control variables influence on residents of the respiratory system, the per capita GDP and population density exhibit positively effect on public health, whereas,health expenditure per capita for residents show negatively effect on public health at 1% significance level.It is indicated that as per capita health expenditure increase 1%, the deaths from lung cancer and respiratory will decrease 0.362% and 0.543%, respectively.[Conclusion]Forest will improve the level of public health by absorbing smoke and dust emissions. In order to improve the level of public health, it is important that not only control pollution from the source through legal and enforcement measures, but also promote afforestation, increase forest coverage rate, expand absorption ability of the tree area, effectively improve the level of prevention and control of plant diseases and insect pests, etc.

Key words: solids discharge, public health, smoke and dust, forest, environment, 3SLS