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I'm not crazy, the attack has begun.
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Discussion Starter #42
"Residual ozone becomes apparent to sensitive humans in the range of 0.01 - 0.03-ppm"

122354


0.03ppm of 1kg (1m^3 of air) is 30ug. Granted if it was detectable at 0.01 then that would be so.

Debatable if it could ever be smelt, and curiously the lowest levels are actually by the roadside. So if you are going to smell it anywhere in London it looks like it is away from the road network. That is not what I referred to above when someone implied smelling NOx from an iding car.

I presume that is due to air mixing and it would not get a chance to become 'generated' by NOx.

Consider the WHO guidelines "In the EU, the current target value for ozone concentrations is 120 µg/m3".

Well, the map is clearly not all red, so it's way lower than the WHO guidance.
 

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I'm not crazy, the attack has begun.
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Discussion Starter #43
I'll have to PM you about my personal work.
 

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CO2 emissions from transport have not declined, cars have grown in size and number. As Donald says diesel is a side issue.

Lower national speed limit to 60mph - more efficient and pressure to reduce miles.
Promote smaller more efficient cars.
Promote walking / cycling.
Greater options of working from home via internet.

Less cars driving fewer miles more efficiently.
 

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I'm not crazy, the attack has begun.
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Discussion Starter #45
122355



"
Why is ozone lower in the middle of London?
"

"Some of the pollution created by cars reacts with ozone and causes it to change into other chemicals. This means that ozone is on average lower in the middle of London and close to busy roads. "


Heh.

So car exhausts actually reduce ozone?

.. confused...?
 

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Discussion Starter #47
TBH I am a bit confused by this too.

So, MORE NOx means LESS ozone?

I thought NOx was a precursor to ozone, not something that scrubbed ozone out.

hmm ...

122357
 

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Discussion Starter #48
The main substance of 'smog' and formation with ozone is that it is a reaction with hydrocarbons and CO, neither of which diesels emit very much of if at all, while petrol cars shower the stuff out.

So it seems diesel NOx is doing petrol emissions a favour by neutralising the ozone with which petrol emissions would form smog.

NOx actually reduces ozone and smog levels.

Is this wrong?
 

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Whilst the ozone issue is not irrelevant for this discussion, especially if one considers role of blown-in ammonia, a more direct issue is the class of chemicals known as SMOG which IS directly caused by NOx and sunlight and IS observable by humans.
 

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Again in theory 3 way catalysts eliminate HC emissions from petrol engines, it is well documented that real world urban driving with cold startups spew the stuff out. Then again HC emissions are not only vehicle related.
 

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Above reference implicating Nox in smog formation is basic enough for anyone with Chemistry Highers (ok A levels) to follow.

Summary, reducing urban Nox will reduce smog formation and improve perceptible by humans air quality.
 

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Discussion Starter #54
Yes, smog = NOx (from diesels) + HCs from petrols.

But also ozone + HCs from petrols = smog

and NOx from diesels + ozone = fresh air

So petrols would still form smog if there were no diesels, but diesels would NOT form smog if there were no petrols.

Surely that makes petrols to blame. Ban all petrols = no smog.

Which one is to blame?

But what is the alternative?
 
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