文章基于環境污染的健康效應的視角,通過考察環境污染對居民健康的負面影響,進而經由健康水平影響有效勞動、經濟產出及福利水平的作用機制,在一個擴展的Ramsey模型中探討了環境污染、健康人力資本與經濟增長之間的動態關系,運用數值模擬的方法對模型的穩態特征做了比較靜態分析和政策影響分析。研究表明:(1)代表性個人的"時間偏好率"直接影響著經濟的動態行為與長期特征;(2)當考慮污染的健康效應時,環境政策與均衡產出和福利水平分別呈不完全相同的倒"U"型關系。具體來看,在"時間偏好率"非常大(即,主要關注當前財富價值,較少關注未來財富價值)的經濟體中,增加環境治理投資可能會擠占物資資本積累,然而健康狀態不被重視,這是因為此時健康人力資本水平主要由消費水平而不是健康支出決定;而在"時間偏好率"非常小的經濟體中,增加環境投資和健康投資都不會擠占物質資本積累,此時健康人力資本水平主要由健康支出而不是消費水平決定。再者,基于環境投資目的的"環境稅"會對與健康人力資本相關的參數變化產生反應,會顯著影響"最優環境稅"和每一環境稅所對應的均衡產出與福利水平。文章的經濟學含義以及政策啟示在于:政府在制定環境政策時,面對著"環境污染→社會成員健康水平→人力資本的有效勞動→經濟產出""環境投資(環境稅)→物質資本投資→經濟產出"的雙重影響關系,亦即,面臨"經濟產出"與"社會福利"的權衡,最終的權衡決策取決于決策者所代表主體的"時間偏好率"。

This paper studies the relationship between environmental pollution,health human capital and economic growth in an extended Ramsey model with assumption that the main consequence of pollution is the deterioration of individuals’ health and the effective labor is determined by the health of the workers. And then it applies the numerical simulation method to analyze comparative statics and environmental policy effect. The paper findings indicate that: first,individuals’ subjective rate of time preference directly affects the dynamic and long-term characteristics of the economy. Second, when considering the health effects of pollution,environmental policies and equilibrium output and social welfare are not exactly the same inverted‘U’relationship. Specifically,in an economy with the high rate of time preference,which pays more concern to the current value of wealth while less concern to the value of future wealth,increasing environmental investment will squeeze out the accumulation of material capital,but the health status has not been paid attention to; this is because health human capital is mainly determined by consumption level rather than health expenditure.In an economy with a very small time preference rate,increasing environmental investment and health investment will not expropriate physical capital accumulation. At this time,health human capital is mainly determined by health expenditure rather than consumption.Furthermore,the environmental tax for environmental investment purposes will respond to changes in parameters related to health human capital,which will significantly affect the optimal environmental tax and the level of welfare corresponding to each of the environmental tax. The study has such important implication: when developing environmental policies,government faces the trade-off between economic output and social welfare,which depends on the decision-maker’subjective rate of time preference on behalf of individuals.