1886年,世界第一辆汽车问世.当时谁也不会想到,它会成为人类必不可少的、应用最广泛的交通工具,给人类的经济发展和社会生活带来了极大的方便;然而,人们更不会想到,它也给人类带来了严重的污染,对健康和生命造成了极大的威胁.40年代初,美国第三大城市洛杉矶上空出现浅蓝色的光化学烟雾,有时持续几天不散,使大气可见度大大降低,许多人喉头发炎,鼻眼受到刺激,而且有不同程度的头疼,这就是世界著名的公害事件 In 1886, the world’s first car came out. At that time, no one would have thought that it would become an indispensable and widely used vehicle for humankind, bringing great convenience to human economic development and social life; however, People do not even think that it has also brought serious pollution to humanity, posing a great threat to health and life. In the early 1940s, pale blue photochemical smog appeared in the sky over Los Angeles, the third largest city in the United States, sometimes continuing. After a few days, the visibility of the atmosphere is greatly reduced. Many people have inflammation of the throat, nose and eyes are stimulated, and there are different degrees of headaches. This is the world famous pollution incident.