“ In the USA, ” states the book The Earth Report 3, “a 1989 report by the Environmental Protection Agency estimated that more than 900,000 tonnes of toxic chemicals are pumped into the air every year. ”
इस संख्या को अल्पानुमान समझा जाता है क्योंकि इसमें लाखों मोटर गाड़ियों से निकला धुँआ शामिल नहीं है ।