In 1956 the UK Government created history with the first Act of legislation to deal with air pollution anywhere in the world. Unfortunately this wasn't the government being ahead of their time or being particularly 'green'. It was the indirect result of a four-day City of London fog in December 1952 on a scale never seen before.
London was no stranger to fog. By 1807 they were so frequent (and so polluted they were yellowish-brown) that they were known as 'London particulars' - distinct from the clean, white fogs of rural areas. They were also known as 'pea-soupers'. Fogs so thick that people could not see even as far as the other side of the street were noted in 1813, 1873, 1880, 1882, 1891, 1892 and 1948. The East End of London was often the main area that suffered, as it was flat and crowded and had a large number of factories producing pollution and particulates (particles of dust or soot suspended in the air).
Particulates cause a large number of problems. They can include many toxins and some are carcinogenic. They are mainly associated with respiratory problems, coughs, colds, excessive mucus production, wheezing and shortness of breath, asthma, bronchitis, emphysema, and general loss of lung efficiency.
In those early days they were caused by coal-burning in homes, and other factory pollutants, but by the 1950s traffic played a large part. The problem regarding smog is mainly the mixture of sulphur dioxide and smoke - the two pollutants together have a much more wide-ranging effect than either in isolation.
December, 1952 was part of a very cold winter with near-freezing temperatures, so lots of coal fires were burning to try to keep people warm. Wind had brought in other pollutants from the Continent and then it dropped, so not dispersing any of the smog, and all this became trapped under an 'inversion of an anticyclone that had developed over southern parts of the British Isles during the first week of December'.
The fog started on 5 December, and while it did not appear worse than any previous fog, by nightfall visibility had dropped and continued dropping over the next few days. Pedestrians couldn't see properly to walk the streets. It affected road, rail, air and river transport. Only the London Underground stayed running, but with no other transport available, it became impossible for most people to travel that way.
The effects were felt almost immediately, starting with livestock at Smithfield Market. Human casualties began on around the third day. Of deaths in the over-45s, 90% were due to heart and lung problems, and the number of babies dying doubled. Even after the air had cleared, people continued to die of the effects. In total, 1597 extra deaths were recorded within the County Of London1. Add the surrounding areas to this total, as other areas in the south were also affected, and there was an estimated 4,000 excess deaths. However, the Government stopped recording figures after a few weeks, and it has been suggested that over 12,000 excess deaths were caused by the four-day fog.
Following this devastating 'fog', smokeless zones were enforced by certain local authorities, including the City of London, which banned the burning of domestic fuel. Many resisted this change, as smokeless fuel was expensive, but the Clean Air Act of 1956 followed (arriving in the same year as another notable fog).
The Act was revised in 1968 to add a directive that coal-burning industries should use tall chimneys. Although this helped prevent smogs in London, it probably didn't improve the air quality of the areas the pollution then drifted over, and contributed to acid rain in other countries.
Similar effects are seen in hot sunny areas with lots of traffic, as the chemicals in car emissions react with the sun, creating ozone. This is covered by acts such as the Environmental Protection Act 1990. The Clean Air Act 1993 is the latest version to protect us from what comes out of a chimney.
If your house has a blocked-up fireplace and you would like to reopen it, remember that only smokeless fuels can be used in some areas, and the preference is for 'coal-effect' gas or electric fires (although of course, gas and electricity have their own emissions at source).
Air quality is still an issue in London and other cities in the UK and transport is the fastest-growing cause of pollution. However, rural areas do not necessarily enjoy air purity as ozone formed in towns can travel into rural areas. Some pollutants help to destroy the ozone, so in areas of less traffic, more ozone is formed, creating problems in quieter areas too.