Let's Learn Some Mechanical Engineering (Or, A Lesson on What CausesPollution)

IC (Internal Combustion) Engines are the engine (pun intended) of growth and progress of human civilisation. We cannot live without them. All engines cause pollution. Even Petrol Engines cause pollution. The question is why, when and how much.

1. Large engines do not necessarily cause more pollution. On the contrary, it is the cheap, small engines of scooters and auto-rickshaws that pollute more. A single five year old scooter or a TSR (Three Wheeler Scooter Rickshaw) will, as a general rule, pollute more than three or four petrol cars of the same vintage. A poorly maintained TSR, even when running on CNG, can pollute more than ten cars.
2. Overloaded automobiles cause more pollution. So, a two-wheeler with two or three passengers will pollute far more than a car with four passengers.
3. An idling automobile, typically one standing at traffic signals, pollutes several time more than when it is moving.
4. An IC engine, whether of a car or of a scooter (2/3 wheeler) is best run at 60-70% of its maximum power. If you overload it, it spews toxic gases and particulates. You can easily understand that it is far easier to overload a two-wheeler or a three-wheeler because it is underpowered to start with. We are not all riding Harley Davidsons, are we? Ours are equipped with puny 100-200cc engines.
5. Carbon Dioxide is not a pollutant. It is merely a Green House Gas. It causes global warming as told by environmentalist. It does not cause pollution. Oxides of Nitrogen (NOx) and Suspended (Fine) Particulate Matter (SPM) are pollutants. Sulphurous gases are pollutants too. But, with Euro 3/4 diesel now being sold, there is virtually no sulphur in automobile exhaust. That leaves only NOx and SPM.
6. A typical farmer and his children are subject to far more SPM due to dust in the fields, burning of hay and other farming activities. So, Delhiites are not the worst hit citizens of India.
7. A poor woman inhales more carbon soot, carbon monoxide (a pollutant), sulphurous fumes and SPM in a day's cooking than an average Delhiite does in a year.
8. Pollution is a relatively local phenomenon. Pollutants of air do not travel far and wide. They settle down or get washed down in rains. They also disperse and become less harmful. Though these processes do not neutralise all the pollutants completely, most are taken care of nature in due course. Pollution overload does happen and that requires strong measures. Pollutants tend to linger longer in humid air as they from aerosols with water droplets. This typically causes the Delhi smog. In my view Delhi still does not have a pollution overload.
9. GHG is a global phenomenon. These gases ride on winds and affect global environment. That is why we have Kyoto and Paris like international conferences to handle them. We do not have international conferences on NOx and SPM since they are local phenomena.
10. Large cars, such as those 2+ litre SUVs now banned by the Supreme Court, produce more carbon dioxide since they burn more fuel. They do not necessarily pollute more. Again, carbon dioxide is not a pollutant. It does not cause asthma nor burn your eyes.
11. Diesel Engines have a reputation of being big polluters. This is not as true for new cars. If maintained well and run properly, they will not pollute significantly more than petrol cars. In any case the Pollution Under Check (PUC) certification is supposed to ensure that their pollution remains within limits.
12. If we need to have diesel cars that should pollute even less, we need to tighten the parameters of PUC certificate. This will compel the car owners to spend more to maintain them in fine fettle. That will be a bigger discouraging factor for potential diesel car buyers than the one-time green cess. This will also ensure that diesel cars registered in Gurgaon, NOIDA or Faridabad, but run in Delhi become less polluting. You cannot levy a cess on such cars which are registered outside, but you can subject them to the more stringent PUC certification if they enter the borders of Delhi.
13. A standing car does not pollute, a moving car does. Or more specifically, it is a car-trip (or a scooter-trip) that pollutes. If you keep odd or even numbered cars off the road, it does not reduce total car-trips by half. In lieu of private car trips we will have taxi-trips and TSR-trips. And, TSRs pollute more than cars. Even if some people use buses, it does not cut pollution by half. Buses are generally poorly maintained and pollute more than permissible. An overloaded bus is a smokestack.

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