Almost three billion people still burn dung, twigs, and other traditional fuels indoors to cook and keep warm, generating noxious fumes that kill an estimated two million people each year, mostly women and children. Likewise, just a hundred years ago, the average American family spent six hours each week during cold months shoveling six tons of coal into the furnace (not to mention cleaning the coal dust from carpets, furniture, curtains, and bedclothes).
电力令人类受益巨大。将近三十亿人仍靠在室内燃烧牛粪、树枝和其他传统燃料来做饭取暖，由此产生的有毒烟雾每年估计致死两百万人，其中多数是妇女和儿童。同样，短短一百年前，普通美国家庭每周花费6小时时间在寒冬腊月将6吨燃煤铲进炉灶（而这还不算清理地毯、家具、窗帘和被褥灰尘的时间）。如今在发达国家，电炉和暖器已经让室内空气污染成为过去。