Judging by analysis of acid rain samples collected at Taipei Botanic Garden since 1981 by Chin Heng-piao of the Taiwan Forestry Research Institute, the nitric acid content in Taipei's acid rain (resulting from traffic exhaust) is growing at a faster rate than its sulphuric acid content (from industrial fumes).
根據林業試驗所林業推廣組主任金恆鑣由民國七十年至今，持續在台北市植物園取樣、分析雨水的結果，台北市雨水中硝酸（交通工具所排放的廢氣形成）的成長率超過硫酸（工廠廢氣形成）。