EFFECTS OF COAL-BASED AIR POLLUTION ON MORTALITY RATES: New evidence from nineteenth century Britain
01 Nov 2018
Industrialised cities in mid-nineteenth century Britain probably suffered from similar levels of air pollution as urban centres in China and India do today. What’s more, the damage to health caused by the burning of coal was very high, reducing life expectancy by more than 5% in the most polluted cities like Manchester, Sheffield and Birmingham. It was also responsible for a significant proportion of the higher mortality rates in British cities compared with rural parts of the country.
These are among the findings of new research by Brian Beach and Walker Hanlon, published in the November 2018 issue of the Economic Journal. Their study shows the potential value of history for providing insights into the long-run consequences of air pollution.
From Beijing to Delhi and Mexico City to Jakarta, cities across the world struggle with high levels of air pollution. To what extent does severe air pollution affect health and broader economic development for these cities? While future academics will almost surely debate this question, assessing the long-run consequences of air pollution for modern cities will not be possible for decades.
But severe air pollution is not a new phenomenon; Britain’s industrial cities of the nineteenth century, for example, also faced very high levels of air pollution. Because of this, the researchers argue that history has the potential to provide valuable insights into the long-run consequences of air pollution.
One challenge in studying historical air pollution is that direct pollution measures are largely unavailable before the mid-twentieth century. This study shows how historical pollution levels in England and Wales can be inferred by combining data on the industrial composition of employment in local areas in 1851 with information on the amount of coal used per worker in each industry.
This makes it possible to estimate the amount of coal used in over 581 districts covering all of England and Wales. Because coal was by far the most important pollutant in Britain in the nineteenth century (as well as much of the twentieth century), this provides a way of approximating local industrial pollution emission levels.
The results are consistent with what historical sources suggest: the researchers find high levels of coal use in a broad swath of towns stretching from Lancashire and the West Riding down into Staffordshire, as well as in the areas around Newcastle, Cardiff and Birmingham.
By comparing measures of local coal-based pollution to mortality data, the study shows that air pollution was a major contributor to mortality in Britain in the mid-nineteenth century. In the most polluted locations – places like Manchester, Sheffield and Birmingham – the results show that air pollution resulting from industrial coal use reduced life expectancy by more than 5%.
One potential concern is that locations with more industrial coal use could have had higher mortality rates for other reasons. For example, people living in these industrial areas could have been poorer, infectious disease may have been more common or jobs may have been more dangerous.
The researchers deal with this concern by looking at how coal use in some parts of the country affected mortality in other areas that were, given the predominant wind direction, typically downwind. They show that locations which were just downwind of major coal-using areas had higher mortality rates than otherwise similar locations which were just upwind of these areas.
These results help to explain why cities in the nineteenth century were much less healthy than more rural areas – the so-called urban mortality penalty. Most existing work argues that the high mortality rates observed in British cities in the nineteenth century were due to the impact of infectious diseases, bad water and unclean food.
The new results show that in fact about one third of the higher mortality rate in cities in the nineteenth century was due to exposure to high levels of air pollution due to the burning of coal by industry.
In addition to assessing the effects of coal use on mortality, the researchers use these effects to back out very rough estimates of historical particulate pollution levels. Their estimates indicate that by the mid-nineteenth century, industrialised cities in Britain were probably as polluted as industrial cities in places like China and India are today.
These findings shed new light on the impact of air pollution in nineteenth century Britain and lay the groundwork for further research analysing the long-run effects of air pollution in cities.
‘Coal Smoke and Mortality in an Early Industrial Economy’ by Brian Beach and W. Walker Hanlon is published in the November 2018 issue of the Economic Journal.