Chronicle (Zimbabwe) - - Busi­ness -

THE air that we breathe is com­posed of gases and par­tic­u­lates which when in their cor­rect pro­por­tions do not pose any threat to our lives. Hu­man ac­tiv­i­ties, how­ever, re­sult in emis­sions which are termed an­thro­pogenic sources of air pol­lu­tion such as com­bus­tion of fossil fu­els in in­dus­try and mo­tor ve­hi­cles.

A marked de­te­ri­o­ra­tion in air qual­ity has been noted in most ur­ban set­tle­ments and in­dus­tri­alised ar­eas in­clud­ing Harare. Broadly speak­ing, cars and trucks cause air pol­lu­tion through­out their life, in­clud­ing air pol­lu­tants emit­ted dur­ing ve­hi­cle oper­a­tion, re­fu­elling, man­u­fac­tur­ing and dis­posal.

Na­tion­ally, the num­ber of ve­hi­cles has been in­creas­ing at an alarm­ing rate in the past decade. Old or sec­ond-hand ve­hi­cles pose the great­est threat to hu­man health as well as the en­vi­ron­ment as their com­bus­tion ef­fi­cien­cies are dras­ti­cally low due to worn out me­chan­i­cal parts and the ab­sence of in built pol­lu­tion abate­ment tech­nol­ogy that is avail­able in newer mod­els.

Air pol­lu­tion from cars and trucks is cat­e­gorised into pri­mary and sec­ondary pol­lu­tion. Pri­mary pol­lu­tion is emit­ted di­rectly into the at­mos­phere while sec­ondary pol­lu­tion re­sults from chem­i­cal re­ac­tions be­tween pol­lu­tants in the at­mos­phere. Th­ese chem­i­cals can cause mild to se­vere ir­ri­ta­tion to the eyes, nose, throat and lungs. They can also be ab­sorbed into the body and cause de­te­ri­o­ra­tion in gen­eral health.

The ex­tent of th­ese detri­men­tal ef­fects on peo­ple’s health is re­lated to the length of time one is ex­posed to ve­hi­cle emis­sions, the con­cen­tra­tion of fumes breathed in and var­i­ous other fac­tors such as age and health sta­tus of the per­son ex­posed. The fol­low­ing are the ma­jor pol­lu­tants from mo­tor ve­hi­cle ex­hausts: Par­tic­u­late Mat­ter (PM) Hy­dro­car­bons (HC) Ni­tro­gen ox­ides (NOx) Car­bon monox­ide (CO) Sul­phur diox­ide (SO2)

Green­house gases What is be­ing done to curb air pol­lu­tion from ve­hi­cles?

From 2014 to date, the En­vi­ron­men­tal Man­age­ment Agency (EMA) con­ducted road blocks na­tion­wide and per­formed road­side ve­hi­cle ex­haust emis­sions tests and for each year com­pli­ance sta­tus was recorded. The own­ers of non-com­pli­ant ve­hi­cles were fined and the ve­hi­cles were com­pelled to be ser­viced. It is un­for­tu­nate that the pro­por­tion of ve­hi­cles whose ex­haust emis­sions com­plied stip­u­lated air emis­sions stan­dards for Zim­babwe have been de­clin­ing since 2014 to date. The im­pli­ca­tion is that more ve­hi­cles are pol­lut­ing the air that we breathe. What Causes A Ve­hi­cle To Be Smoky? There are many rea­sons why a ve­hi­cle might emit con­tin­u­ous smoke:

spark plugs need re­place­ment or clean­ing ig­ni­tion tim­ing needs ad­just­ment worn pis­ton rings, pis­tons or cylin­der bores worn valve stem guides or seals sump over-filled with engine oil blocked air cleaner

faulty elec­tronic or me­chan­i­cal con­trols in parts such as the choke poor, con­tam­i­nated or in­cor­rect den­sity or grade of fuel blocked or dam­aged fuel fil­ter

in­cor­rectly set or dam­aged fuel in­jec­tors or fuel pump

In­cor­rectly set or dam­aged turbo or su­per charges.

What leg­is­la­tion gov­erns at­mo­spheric emis­sions?

Ve­hi­cle emis­sions are reg­u­lated in terms of the En­vi­ron­men­tal Man­age­ment Act (Cap 20:27), sec­tions 63-68 as read with Statu­tory In­stru­ment 72 of 2009 (En­vi­ron­men­tal Man­age­ment [At­mo­spheric Pol­lu­tion Con­trol] Reg­u­la­tions, 2009). The law stip­u­lates the air emis­sion qual­ity stan­dards per­mis­si­ble for var­i­ous classes of ve­hi­cles and other auto mo­biles fo­cus­ing on pa­ram­e­ters such as car­bon monox­ide, lead, ni­trous ox­ides, par­tic­u­late mat­ter and sul­phur diox­ide. Rec­om­men­da­tions to mo­torists Reg­u­lar ser­vic­ing of ve­hi­cles greatly re­duces ex­haust air pol­lu­tants as this fa­cil­i­tates bet­ter engine com­bus­tion ef­fi­ciency. Even older ve­hi­cles can per­form bet­ter when reg­u­larly ser­viced and worn out parts are con­stantly re­placed with new ones.

Fig­ure above: Pro­por­tions of ve­hi­cles whose ex­haust emis­sions com­plied with Zim­bab­wean stan­dards from 2014 to 2016, source EMA road in­spec­tion report

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