Diesel exhaust particulate can be reduced with filters and NOx reduced by urea sprays such as the Mercedes BlueTec system. I guess spot checks would be required to see if the equipment is installed and working. Dimethyl ether DME can be used in LPG cylinders and bowsers and largely solves these problems when used in modified engines. Biodiesel is in limited supply but still has particulates but not SOx. Battery trucks and buses have short range. Then there is Audi synthetic 'blue diesel' which apparently ticks most boxes except availability.

Therefore diesel problems can be largely solved it comes down to cost and convenience. I guess the trick is to gradually tighten the noose until we can accept that cost.

Diesel and petrol engines can and do run on CNG, and as such produce less pollution than exhaust filtered, diesel or petrol engines!

Moreover, we have many, many year's worth of supply, or we did before the mad hater's tea party, sold most of what comes from our ground, all while we import sulfur laden foreign fuel, some of it ultra costly diesel, even though our own traditional sweet light sulfur free crude will run diesel engines as is and unrefined.

And recoverable at under $10.00 a barrel!

However, some simple chill filtering removes a soluble wax content that if left, can foul the injectors on cold frosty mornings. Moreover, 4.7% methanol improves the energy coefficient markedly, while further reducing the black smoke produced under load!

As Sam (kick the ball) lamb chop chewing kickovitch, would say, you know it makes perfect sense!
Alan B.

Before the advent of fossil fuels most of us had a life expectancy of not much over 30 years. We died worn out & broken by the strenuous labour involved in producing or catching our food, of health complaints now made trivial by modern fossil fuel based medicines, or of lung disease induced by living in smoky houses where cooking was on fires of wood or dung, & lighting was by burning animal fat.

If I am now to die at 80 years, of lung problems induced by diesel smoke from the machinery that produces or delivers my food, or even that drives my neighbours work ute or car, I'll accept that as a fair trade off.

I don't like the stuff much, smelly stuff raw or burnt, but I use it because it is the most suitable fuel for my generator, tractor & pumps.

So fellers, when our life expectancy starts reducing from some real problem or other, let me know. Meanwhile as doctors please concentrate on the new health problems caused by our increased life span, not some contrived greenie problem, that wouldn't exist if we weren't living so long today.

In reply to Hasbeen - It is true that our health and longevity have improved dramatically over the last 150 years. This is due in large part to public health measures, regulations and infrastructure. It would be a mistake to think that oil and large scale electricity access (which only became widely available during the 20th century) were the reason for these improvements as most of the health gains preceded this.

Around 3.4 million deaths each year are attributable to ambient (outdoor) air pollution globally. That's as big a problem for world health as smoking. Whilst much is in the developing world, around 100,000 deaths occur in UA and 170,000 in EU.

And it is not just old people that suffer asa you have suggested, children are disproportionately vulnerable and affected by air pollution, especially in our larger cities.

That is why is it taken seriously by doctors and governments. Aside from deaths, the lost productivity and illness cost are a major economic drag as explained in our article and as we point out they can be quite easily remedied with simple legislation and policy changes.

What is the particulate level for coal fired steam locomotives, both road and rail?

Presumably, the good doctors are aware that, thanks to the stupidity of the SA government forcing the closedown of coal-fired power stations, many SA electricity consumers have in desperation installed diesel generators for power restoration during SA blackouts.