Clean air act amendment ( 1987 ) established a national air - quality standard for ozone 1987年潔凈空氣法修正案建立了空氣的國家空氣質(zhì)量標準。
Clean air act amendment ( 1977 ) established new deadlines for cleaning up polluted areas ; also required review of existing air - quality standards 1977年潔凈空氣法修正案確定了清理被污染區(qū)域的新期限,同時要求對現(xiàn)行空氣質(zhì)量標準進行評估。