近幾十年來，空氣汙染和生理健康之間的關係一直是一項備受矚目的議題。然而，空氣汙染和心智健康的關係卻鮮少人知道。因此，本研究利用中老年身心社會生活狀況長期追蹤調查的資料，探討空氣汙染對憂鬱情形、生活滿意度和認知功能表現的影響。
由於早期的空氣汙染資料不齊全，因此本研究僅以PM10、CO、SO2和NO2之資料去做分析。本研究參考美國環保署所訂定的各項空氣汙染物的副指標，並以這些副指標的平均值去建構一項綜合性空氣汙染標 (AQI) 來代表本研究空氣汙染的數值。
除了加入個人固定效果外，本研究更以風速作為空氣汙染的工具變數來解決內生性的問題。實證結果發現無論以何種模型去做估計，空氣汙染對於心智功能確實存在顯著負面的影響。而空氣汙染對生活滿意度及憂鬱情形則無一致顯著的影響。此外，為確保結果的穩健性，本研究進一步以不同方式去做估計，結果發現即使改以不同期間空氣汙染的數據或採經拔靴法校正後的標準誤去做估計，空氣汙染仍顯著地對認知表現有不良的影響。另外，本研究更以PM10、CO、SO2和NO2四項單一汙染物的副指標分別去做估計，發現以CO副指標去做估計，即使標準誤經拔靴法校正後，結果仍和AQI之結果一致。
總而言之，空氣汙染對人類的健康造成了嚴重的損害；因此，有關當局與大眾應合力控制汙染量，共同創造更健康舒適的生活環境。

Over the last few decades, the association between air pollution and physical health has been a high-profile issue. However, few are known about the relationship between poor air quality and mental health. Therefore, in this study, I investigate the causal effect of air pollution on depression, life satisfaction and cognitive performance by analyzing data from the Taiwan Longitudinal Study on Aging (TLSA).

Due to the availability of air quality data, we only analyze four pollutants: PM10, CO, SO2 and NO2. In order to estimate the overall effect of these various pollutants, I refer to the criteria of sub-indices established by the Environmental Protection Administration (EPA) in US and use the average of these sub-indices to construct a new index, AQI, as a proxy for air pollution.

In addition to adding the individual fixed effect into our regressions, I also employ wind speed as an instrumental variable to address problems of endogeneity. I find that AQI does have a saliently detrimental effect on cognition in both the fixed effect panel data model and the model of instrumental strategy along with individual fixed effect, but there is no consistent significant effect on one’s depression condition and life satisfaction.

Furthermore, I use different period of exposure to air pollution, adopt sub-indices of CO, PM10 and NO2 as indicators of air pollution or employ the wild bootstrap approach for robustness check. The significant effect of air pollution on cognitive performance holds. Besides, I also estimate the effects of the sub-indices of PM10, CO, SO2 and NO2 on mental health, and find that the results of the sub-indices of CO is consistent with AQI even if I adopt the wild bootstrap standard errors.

To sum up, the severity of the air pollution cannot be overemphasized; thus, the authorities along with the public should make their efforts to control air pollution for the sake of health.

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