隨袋徵收政策的影響──來自合成控制法的證據

Effects of a Per-Bag Trash Collection Fee Program: Evidence from a Synthetic Control Method

為了減少廢棄物，垃圾按量收費政策已在全世界廣泛的執行。本文旨在評估新北市的垃圾按量收費政策──隨袋徵收政策──對家庭廢棄物處置的效果。依據隨袋徵收政策，居民傾倒未分類垃圾時需要使用付費購買的認證垃圾袋，但傾倒已分類垃圾（包含廚餘以及可回收物）不需付費。我們運用合成控制方法控制不同縣市在垃圾處置上的時間趨勢，並以縣市層級的政府公開資料估計，發現隨袋徵收政策之實施降低未分類垃圾量約27.7%以及回收量約20.8%。在短時間內，廚餘回收量幾乎翻倍，但其效果隨時間遞減。整體而言，該政策降低總垃圾量約17.4%。這些結果支持垃圾單位計價不僅造成未分類廢棄物的垃圾迴避，同時也導致可回收物的垃圾迴避。最後，我們估計隨袋徵收政策每年為家戶帶來30000元的社會福利增益。

Pay As You Throw (PAYT) policies are implemented worldwide to reduce waste. This paper estimates the effects of a PAYT policy in New Taipei City─per-bag trash collection fee (PBCF) program─ on households’ waste disposal. Under the PBCF, people have to buy certified bags for their unsorted waste, while sorted waste (food and recyclable waste) is disposed of for free. We apply a synthetic control method that allows cities/counties to have different trends in waste disposal. The estimation results using the city/county-level administrative data suggest that the PBCF decreases unsorted waste by about 27.2% and recyclable waste by about 20.8%. Food waste almost doubles in the short term, but the magnitude gradually reduces over time. Overall, the program reduces total waste by about 17.4%. These results suggest that waste avoidance behavior resulting from the PBCF appears not only in unsorted waste but also in recycling. Finally, we estimate that the welfare gain from the PBCF is about 30,000 NTD per household per year.