Ex­haust Con­trols Air Pol­lu­tion

Even if still charged by coal-fired elec­tric­ity, at least an EV isn't belch­ing ex­haust fumes all over your kids as you drop them off. Car ex­haust is toxic, and as we wait for bat­tery tech to im­prove, we must rely on ever-more so­phis­ti­cated fil­ters to "cle

Science Illustrated - - TECHNOLOGY -

On a Fri­day af­ter­noon in Jan­uary 2017, toxic smog veils Bei­jing, just like it has many times be­fore, caus­ing a red alert. Nurs­ery schools and schools close, old pol­lut­ing cars are not al­lowed on the streets, and heavy in­dus­try such as steel rolling mills are asked to close down. The huge city comes to a halt. Dur­ing the next few days, peo­ple try to stay in­doors, and wear masks if they ven­ture out­side. The ci­ti­zens of Bei­jing know very well that this thick, acrid smog should not be un­der­es­ti­mated.

In 2014, China’s prime min­is­ter, Li Ke­qiang, of­fi­cially de­clared war against air pol­lu­tion, promis­ing the pop­u­la­tion to “make the sky blue again”. Now, the ci­ti­zens of Bei­jing are be­gin­ning to see the re­sults.


In a life­time, about 250 mil­lion litres of air pass through our lungs. That's a sim­i­lar vol­ume of gas as the amount of hy­dro­gen in the Hin­den­berg. So If the air is even slightly pol­luted, the to­tal quan­tity of tox­ins end­ing up in the body is tremen­dous.

For decades, sci­en­tists have known that smog causes dis­eases such as asthma, bron­chi­tis, lung can­cer, and other breath­ing dif­fi­cul­ties. In re­cent years, other com­pli­ca­tions have been added to the list – in­clud­ing de­men­tia, obe­sity, and ar­te­rioscle­ro­sis. An­nu­ally, some 7.2 mil­lion peo­ple die an early

death, be­cause they breathe harm­ful sub­stances, mak­ing air pol­lu­tion one of the the world’s big­gest en­vi­ron­men­tal prob­lems.

Smog is big trou­ble in China. Six­teen of the world’s most pol­luted cities are lo­cated in the world’s most pop­u­lous na­tion, which it­self is home to a to­tal of 1.4 bil­lion peo­ple.

In Bei­jing, pol­lu­tion ex­ceeds in­ter­na­tional thresh­old val­ues of un­healthy air more than half of the year. On the worst days, the air is worse than chain smok­ing.

China’s ex­tremely un­healthy air is due to a com­bi­na­tion of emis­sions from dif­fer­ent sources. From power sta­tion chim­neys, car­bon diox­ide is emit­ted, the ex­haust pipes of cars fill the air with nitro­gen diox­ide, and am­mo­nia vapour the re­sult of the use of ar­ti­fi­cial fer­tilis­ers. Sev­eral of the gases also com­bine in the air, pro­duc­ing even more tox­ins. In late 2016, a US-Chi­nese study showed that cities with both heavy in­dus­try and heavy traf­fic are tor­mented by ex­tra many ex­tremely harm­ful sul­phate com­pounds, which form based on sul­phur diox­ide, when large quan­ti­ties of nitro­gen diox­ide are present.


But in re­cent years, the toxic gases in the at­mos­phere have been over­shad­owed by a much more wor­ry­ing type of pol­lu­tion: mi­cro­scopic par­ti­cles which are so small that they can en­ter deep into the lungs, pass­ing


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