Sunday 13 January 2019

Atmospheric pollution, illness and the sun

The atmosphere, pollution, health, and the sun

There is currently a great deal of concern about atmospheric pollution, which is said to be killing thousands, if not millions. But of course atmospheric pollution is not a recognised cause of death, and a specific disease must be the true cause of death, with atmospheric pollution being an initiating or an accelerating factor.

Industrial townscape, LS Lowry

Urban and rural deaths

The industrial revolution in the UK and several other countries of Europe commenced in a major way during the 18th century. It was based on the energy released by the burning of coal, and it created a huge amount of atmospheric pollution. The population of the new industrial towns experienced a serious health and survival disadvantage compared to people who remained living in surrounding rural villages.This was shown in a study of Manchester and Liverpool, undertaken by a Manchester physician Thomas Percival (1740–1804). His monograph, “Observations on the population of Manchester and other adjacent places” was published in 1773.
Thomas Percival 1740–1804
Whereas today we would report the number of deaths per 100,000 of the population, in 1773 Percival reported that 1 in 28 of the population of Manchester died each year, and this was similar to the experience of Liverpool, just 50km distant. The population of Manchester was 27,246 at the time. A death rate of 1 in 28 is equivalent to 3571 per 100,000, extremely high compared to present times.

In contrast, the death rate in the surrounding villages was half this, at 1 in 56 of the population. This is equivalent to 1786 per 100,000, again very high compared to  present years (about 900 per 100,000 per year).

The obvious difference between industrial cities and rural villages is atmospheric pollution. The observation of 1773 remained the same two centuries later.


What became obvious in the new industrial cities was the emergence of rickets in children, a result of serious atmospheric pollution blocking the vital benefit of sunlight. The experience in Glasgow was that if the sick children were moved to the coastal fishing villages (from which the families originated), then the rickets would heal and the children’s health would improve.  In Austria, there was also an emergence of rickets in the new industrial cities, with improvement following movement to the mountain villages.

+ tuberculosis

There was an obvious link between rickets (the direct result of lack of vitamin D from sunlight) and tuberculosis. Glasgow, a major industrial city, became the rickets, and then the tuberculosis, capital of the world. The link was also obvious in Austria: it gave rise to the Heidi story in which the sick girl (presumably with tuberculosis) was taken from the city to the clean air of the mountains  and there was restored to good health.

Although atmospheric pollution was a serious health problem for children and adults, a compounding factor was long hours of indoor work. A Manchester surgeon Thomas Bellot stated that it was not uncommon for factory children "to be checked in their growth, to become lame and deformed in their legs...and eventually to die of consumption" as a result of "their long confinement in heated and unventilated rooms, and of their being constantly on their legs during their long hours of labour. [quoted from Peterloo: the Story of the Manchester Massacre, by Jacqueline Riding]


The atmospheric pollution of the early industrial cities caused serious problems up to the mid-20th century, especially in the UK. The winter smogs of London reached a peak in 1952 that lead to the UK Government Clean Air Act in 1956. Following this there was a remarkable improvement in air quality. 

Stalybridge, Manchester 1950
The burning of coal was the major problem, and much of this was for domestic heating. Also, electricity was generated by many small coal-fired power stations that operated very inefficiently. Gas was produced by heating coal. Factories were powered by coal-fired steam engines, and railway steam locomotives were powered by coal. Coal was King, and it underpinned the industrial revolution.


During the 19th century whales were the main source of oil, to be used mainly for lighting. Fossil oil was discovered and came into production at the turn of the century, just in time to prevent the total extinction of whales. It was after the second world war that oil came to be used in place of coal, for domestic heating, electricity production, and diesel locomotives. Natural gas came to replace coal gas and we developed an oil-based economy. This happened at just the right time to enable the effectiveness of the Clean Air Act.

River Thames, London. 1950
The cleaning of the atmosphere of the UK during the second half of the 20th century was remarkable. The diminishing use of coal led to a reduction of  particles of unburned carbon and also a reduction of oxides of the sulphur contaminants of coal. This was helped by the improved and more complete combustion of coal in fewer and larger power stations with much taller chimneys. 

But invisible pollutants continue, mainly carbon dioxide, and as this is heavier than nitrogen and oxygen, much of it it stays in the lower atmosphere. To this is added pollutants from the engines of road traffic vehicles. Diesel engines give more particulate pollutants than petrol engines as the diesel fuel is mush less refined. The growth of road transport has led to a resurgence of atmospheric pollution in our cities. It is the particles of unburned carbon that are responsible for the blockage of sunlight penetration. 


The imperative is to progress from an oil-based economy to electricity, which to be used by transport and domestic heating in particular. Coal, oil and gas must not be used for electricity production, and must be replaced by renewable natural energy sources (gravity, wind, sun) together with nuclear power.

Health effects of atmospheric pollution

Although it is generally considered that atmospheric pollution does not kill directly and it is not a recordable cause of death, this has been subject to a legal challenge in the Uk in January 2019. A girl living close to major road in south London died from "asthma". Her mother is seeking a legal change to record the cause of death as "Atmospheric pollution". 

However there will always be an intermediary disease, in which pollution is a driving factor or an accelerating factor. It is necessary to recognise ways in which atmospheric pollution might damage human health.

There are two major possibilities: pollutants that when inhaled might be toxic, and atmospheric pollution blocking sunlight. Another less important possibility is road traffic accidents due to poor visibility.

China – no visible sun on a "clear" day in Beijing

The nature of atmospheric pollutants

The atmosphere provides the oxygen that is necessary for essential metabolic activities of animal life. Oxygen is put into the atmosphere by the photosynthesis of plants. Oxygen is highly reactive and it readily combines with other atoms to produce oxides, for example carbon dioxide, sulphates, iron oxides. It was only after the evolution of plant life (containing chloroplasts, initially free-living entities)  that oxygen was released into the atmosphere, allowing the evolution of animal life. This was the era of the great oxygenation event, nearly three billion years ago.

Burning carbon fuels inevitably results in the release of carbon dioxide (CO2) into the atmosphere. If carbon is partially oxidised, carbon monoxide (CO) will be released. 

If the combustion of carbon is inefficient, then non-combusted particles of carbon will be released into the atmosphere. Particulate matter is divided into PM-10 (10 micrometers or less) and PM-2.5 (2.5 micrometers or less).

Nitrogen-containing contaminants will be oxidised to nitric oxide (NO), nitrous oxide (N2O) or nitrogen dioxide (NO2). Sulphur-containing contaminants will be oxidised to sulphur dioxide (SO2). These oxides form acids when they dissolve in water.

All these oxides are heavier than oxygen and nitrogen, and they will remain within about 100 metres of ground level. They can be dispersed by strong winds and rain.

Chronic respiratory disease

Our European neighbours referred to Chronic Bronchitis as the “English Disease” (the English referred to syphilis as the “French Disease”). Chronic bronchitis was a common disease in the UK during most of the 20th century, and was characterised by a productive winter cough usually with but sometimes without wheezing. It was often fatal after years or decades of ill-health and respiratory disability. Cigarette smoking obviously added to inhaled smoke pollutants. 

Chronic bronchitis is a clinical term that is used little 
today: it has been replaced by the term Chronic Obstructive Pulmonary Disease (COPD) which puts more emphasis on the obstruction of small airways rather than the production of sputum.

Chronic bronchitis was linked to and caused by inhalation of atmospheric pollutants and cigarette smoke, and its incidence has fallen during the second half of the 20th century. During this time we have experienced a major reduction of atmospheric pollution and also a major reduction of cigarette smoking.

Tuberculosis and the sun

Tuberculosis, with its old name of “consumption” is primarily a lung disease, although it can affect any part of the body from the skin to the brain, heart, and bones. Its close relationship to atmospheric pollution and rickets indicates that reduction of sunlight penetration to ground level is the important common factor. Reduction of vitamin D synthesis damages not just bone development but also immunity. In more recent years AIDS has resulted in an increased risk of tuberculosis in the sufferers.

In the 1950s India also experienced a strong association between rickets and tuberculosis, and once again the common factor was deficiency of sunlight. However, whereas in the UK it was mainly the poor who were affected, in India it was the wealthy. In India poor people worked the fields, while the wealthy people stayed indoors – out of the sun.

Other diseases linked to pollution.

Glasgow became the rickets capital of the world, and then the tuberculosis capital. It was also renowned for the dreadful state of dentition of its inhabitants. It became the lung cancer capital, and during the latter half of the 20th century it became the coronary heart disease capital.

A particular high incidence of deaths from coronary heart disease (CHD) during the 20th century epidemic was in places and people with high levels of atmospheric pollution, cloud cover, and geographical reasons for low sunlight penetration. The populations of places with reduced levels of sunlight penetration have had more CHD deaths as well as an average shorter life expectancy. Also a number of cancers are more common where there is low sunlight penetration.

The mechanism behind this is that vitamin D has an important role in developing important immunological defence mechanisms. These are very important in controlling and preventing the development of CHD and many cancers. 

The UK today

Although there is understandable concern about atmospheric pollution in our cities, mainly the result of diesel vehicles, the pollution levels are nowhere near what they were in the 1950s and before. There is also concern about carbon dioxide production and resultant global warming, but that is something different.

River Thames, London.  2018

Despite present-day pollution the health of the UK population is better than ever and we are living longer than ever. More and more people pass their 90th birthday. There are dire warnings about the future, and in particular that atmospheric pollution will cause thousands of deaths, but deaths from what? A recent statement from the Royal College of Paediatricians indicated that atmospheric pollution in damp winter weather will cause respiratory problems in children, but these are acute infections and nothing that will shorten lives.

The state of the atmosphere depends not just on the production of pollutants but also on their removal by wind and rain, and there is generally no shortage of these in the weather of the UK. On recent visits to London I have been impressed by the brightness of the late afternoon winter sun, but nevertheless when seen from just a modest elevation there is a dark layer of polluted air at ground level. 

London, looking north from Greenwich. Dark polluted air close to the ground is visible

Linz, Austria, looking south across the city from Pöstlingberg, with dark polluted air visible

The far East today

What we experience in London UK, or Linz in Austria, fades into insignificance when we see the amount of atmospheric pollution in, for example, Beijing or Delhi. The pollution levels result in the sun being almost invisible, and penetration through particulates is very much less than through all but the thickest water-containing clouds. 

Of course there is little cloud in these arid cities; there is little rain and very little wind. Face-masks to prevent inhalation of polluted air might be of some benefit, but the major problem must be serious obstruction to sunlight penetration and therefore the impairment of  vitamin D synthesis in the skin.

The effects of blockage of the sun with consequent vitamin D synthesis will not be immediately obvious. As in Glasgow and other European industrial cities more than a century ago, we can anticipate serious health problems in the children who are not yet born. When they are born they are likely to be deficient in vitamin D and likely to develop rickets. Poor immunocompetence is likely to result in more tuberculosis or other infections and illnesses prevalent at the time.

Despite the history of atmospheric pollution in European cities, the importance of blockage of sunlight does not appear to be appreciated by those with responsibilities for public health at present.

Xian, China, 2000. A "bright sunny day". The mountains are no longer visible.