This is a continuaton of the prior post and it also includes a link:
Subsequent to this disaster, they set in motion a plan to convert "soft" coal into "hard" coal by driving off the gasses that were the root of his problem.
Since it was a fairly complex system that had to be put in place, they divided England into a bunch of zones and prioritized them in order of most serious consequences of burning soft coal down to least. I believe they finished this conversion a long time ago. In 1965 it had reached many areas that were mostly suburban / countryside. The complexity was that this also meant they had to convert these districts into the different type of gas that was now supplied for cooking, heating etc. This was like the conversions in the US many years ago when we converted from manufactured gas to natural. All gas using devices had to have different nozzles and air regulators and in many cases were so ancient they had to be replaced. What solved the problem is that when burning coal in crude fireplaces and old fashioned furnaces, there was not any satisfactory way of regulating air inflow to amount of coal on the hearth, hence combustion was VERY inefficient. However when burning the driven off gas and natural gas mixture (precisely maintained ratio) in a modernized appliance this ratio could be adequately maintained.
All good things come with unintended consequences. After the conversion completion in the London area, they lost most of the "Plain" trees ("Plain" is a specific family, not "just any old tree"), as they could not handle the large amounts of direct sunlight that was now available.
Also click
HERE for a more detailed analysis and another link to a similar problem in 1991.
