Six years later I was scrabbling around in the gutters of Piccadilly, central London. I was photographing the kerb stones which appeared to be thickly coated in a graphite-like substance. It was, in fact, the particulates being emitted - mainly - by London’s ageing diesel bus fleet.
What I couldn't see - although those with sensitive chests might have felt - was the nasty nitrogen oxides also being emitted by the diesel engines.
In 1994, the newly-formed Transport for London had introduced the infamous ‘Congestion Charge’, basing it on the level of CO2 emissions from vehicles. And in the global warming panic, the strict meanings of CO2 ‘emissions’ and ‘pollution’ had been dangerously - possibly deliberately - welded into one.
High-CO2 vehicles were ‘polluting’. Reducing CO2 ‘emissions’ had to be a national and local priority. In fact, as I pointed out on many internet forums, replacing London’s 24,000 black cabs with 24,000 petrol Range Rovers would massively improve central London’s air quality.
Living on a busy road in the capital, I had come to realise that the layers of fine dirt and dust on the front door and on the window sills was not just the backwash of living in city, it was mostly particulates, fired from the exhausts of vans, trucks, taxis and many older cars.
It has taken a ridiculously long time for law makers, civil servants and the media to wake up to the threat from diesel engines that are used in stop-start conditions.
Scientific studies showing London’s Oxford Street, and roads in central Oxford, Manchester and Birmingham were among the most polluted in the world seem to be published to no effect.
Certainly, the amount of pollution put out by diesel engines has fallen dramatically in the last few years, but there are plenty of scientists who are concerned that the newest engines are emitting ever smaller particulates, which, ironically, are so small they might get lodged deep in the lungs and even pass into the bloodstream.
Anything from regular stop-start traffic to speed bumps can, for example, cause peaks in nitrogen oxides emissions. The latest estimates are that there are 9500 premature deaths in the capital alone from exposure to pollution.
Then’s there’s the mostly unexplored issue of what happens as diesel engines age and internal components - such as the injectors - wear out. We’ve all seen clouds of black smoke from those tatty 55-plate Mondeos and Astras. And that’s not even considering the damage being done by the huge numbers of hard-driven and high-mileage commercial vehicles.
However, the VW diesel test scandal in the US might be the final push that lines up all everything we know about diesel pollution and starts the avalanche of public opinion that marks the beginning of the end for these engines.
Certainly, some EU6 diesel engines remain ‘clean’ even in city conditions. And Volvo’s use of computer controlled Denso diesel injectors means, the company claims, that the engine will remain inside EU6 pollution parameters for its whole life.
Diesel engines are increasingly complex and expensive to manufacture, however, and units from the later 2000s are now proving expensive in later life as dual mass flywheels, particulate filters and diesel fuel pumps fail expensively.
Ask a London mini-cab driver: the use of low-pollution and ultra-reliable hybrid petrol Priuses and Insights is now common for people who drive for a living.
Weaning us off diesel won’t be easy. The economy is unbeatable, the in-gear performance addictive and the motorway pace undeniable.
The European Union and UK government would also have to untangle CO2-based motoring taxation. Fuel bills might rise, but petrol turbos - especially the upcoming 48V hybrids (which are relatively inexpensive and highly effective - are increasingly convincing.
Selling somebody a 50mpg Golf 1.4 TSI will be no hard thing, but shifting commercial traffic away from diesel is a much bigger task. Here, we have to take a lead from East Asia where the use of clean-burning gas is common for taxis, buses and small and medium commercial vehicles.
Sure, it’s a huge change, but once the US authorities get stuck into measuring the real-world pollution from oil-burning engines, the resulting global publicity could finally usher in the end of the great dash for diesel.
Read more on the Volkswagen emissions scandal:
How the Volkswagen story unfolded
How VW's 'defeat device' works
VW board anticipates more top-line casualties
European cars are affected, says German minister
PSA Peugeot Citroën leads calls for tougher emissions test procedures
Your key questions answered
BMW - why the X5 complied with independent US emissions test
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Blog - VW's scandal has put the entire motor industry under pressure
Blog - Winterkorn pays a high price
Blog - the emissions scandal could sink Volkswagen's US ambitions
Blog - VW's US boss faces the music