On 15/12/2019 11:51, Martin Gregorie wrote:
> On Sun, 15 Dec 2019 12:31:21 +0100, Axel Berger wrote:
>
>> A much higher efficiency is reached by using lean burning engines in the
>> first place, but then you tend to maximise nitrous oxides and there's no
>> easy way to reduce them.
>>
> Indeed, and NOx seems to be the prime concern of those interested in
> cleaning up urban air, now that diesel smoke has mostly disappeared.
>
> IIRC there was concern about heavy metal dust pollution from catalytic
> converters, but that seem to have ben  kicked under the table as well.
>
>
Brake dust was and is another  nasty thing altogether.

The London Tube lines are full of a horrid dirt.

Pollution control is a law of dimisihing returns.

Compared to my youth the Western world is unbelievably clean. We
exported all the pollution to China and SE Asia.



--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.

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