November 1953: A couple walking in London wearing smog masks on a foggy day. (Photo by Monty Fresco/Topical Press Agency/Getty Images)

    The diesel car crisis: how we created a new pollution problem

    27 March 2017

    Air pollution is not a new problem. London has been cursed with pollution for centuries. The diarist John Evelyn published a pamphlet in 1661: Fumifugium, or, The inconveniencie of the aer and smoak of London dissipated together with some remedies. He recommended that the burning of noxious sea-coal be abandoned, substituting instead aromatic woods, and that polluting industries be moved elsewhere — not so very different to proposals introduced 300 years later.

    In the late 18th and 19th centuries came the industrial revolution. Factories belched out fumes which were carried eastward by the prevailing south-westerly winds. The wealthy chose to live in the west sides of our cities while the east became the dirty, deprived and unhealthy slums of the Victorian era.

    Despite numerous calls for action over the decades air pollution only became a national priority following the Great Smog of 1952. During one week of high atmospheric pressure, no wind, and temperature inversion in early December there was a continuous smog day and night so severe that visibility was reduced to two or three yards, bus drivers could not see the edge of the road and road and rail transport came to a halt. It is said that in the East End people could not see their own feet.

    Yet another cry for action followed, but as ever the government was reluctant to act, fearing effects on industry and national wealth. However, on this occasion an inspired epidemiological study was carried out comparing death rates to the previous and subsequent years and to those in cities without the smog. The data showed convincingly that there had been over 4,000 extra deaths in that week in London alone. This startling analysis finally induced parliament to act, and the Clean Air Act was passed in 1956. This introduced ‘smoke control zones’, banning the burning of coal in open fires, re-siting power stations and greatly reducing the combustion of coal in cities.

    The Clean Air Acts of 1956 and 1968 gradually had effect, and the levels of pollution fell steadily. By the 1980s official government policy was that air pollution was no longer a problem, needed no further consideration or action, and so the Clean Air Council was abolished. Despite this bureaucratic confidence by the Departments of Transport, Environment, and Health the data generated by the six pollution monitoring stations in British cities were not available, and indeed were subject to the Official Secrets Act.

    Meanwhile, research into air pollution was being conducted in the United States and to a lesser extent in Europe. The combustion of coal-generated sulphur dioxide and large smokey particles had diminished, and the levels of these pollutants had fallen greatly.

    But instead a new form of pollution generated by vehicles was evident, predominantly nitrogen dioxide and microscopic particles of tar, called PM10 (particulate matter less than 10 micron in diameter) and subsequently PM 2.5 (less than 2.5 micron).

    ‘In Britain each year about 40,000 people’s lives are shortened by an average of some six to 12 months.’

    These tiny particles are not visible to the naked eye and are so small that they are inhaled to the furthermost reaches of the lungs, and can pass across the lung membranes into the blood stream. The idea of inhaling tarry particles into the blood is unappealing to most people and research over the last three decades has confirmed that they are not good for health, causing adverse effects in the function of lungs, blood and blood vessels. Nitrogen dioxide (NO2), meanwhile, is a gas which can irritate the airways, exacerbating asthma, bronchitis and other respiratory conditions.

    Modern pollution at the levels found in our cities does not cause death directly and the health effect in a given individual depends on their innate susceptibility (genetic determinants), their levels of exposure (environment) and the length of exposure, so is hard to predict. However, numerous epidemiological studies that compare matched populations differing only by their levels of pollution show that lifespan is reduced for those living in the polluted areas.

    It is hard to project these studies on to living populations, but the consensus is that in Britain each year about 40,000 people’s lives are shortened by an average of some six to 12 months. Of these deaths 30,000 are attributed to particulates and 10,000 to NO2. Some lives might be shortened by only a few days or weeks, and some may be shortened by several years.

    These numbers have wide confidence intervals and could be significant over- or under-estimates. However, death is an extreme health outcome and it is abundantly clear that the tarry particles and the NO2 of vehicle emissions can and do also make existing health conditions worse, and are particularly deleterious in the young and growing lung, and in the elderly.

    Some 15 years ago the British government made fiscal incentives for diesel cars and other vehicles, on the (largely correct) grounds that these engines generate less greenhouse gases than petrol engines. This policy has been successful in that about 50 per cent of UK cars are now diesels.

    Unfortunately, this has also resulted in a substantial increase in polluting emissions, particularly particulates. The so-called particulate traps on diesel vehicles are ineffective until they reach working heat, which takes 10 to 15 minutes of continuous driving — often not achieved for days or weeks on end by city dwellers or urban vans. They need regular cleansing by a long period of driving when the accumulated particles can be burned up and released into the environment.

    Car manufacturers have catastrophically failed to provide effective technical solutions to particulate emissions. This failure has been covered up by lax regulatory and testing standards. To this has been added the mendacious and wholly unacceptable rigging of the testing process by some, notably Volkswagen, by their own admission over many years.

    What can be done about all this? First, there needs to be a public and political will to change. The publicity around air pollution does seem to be creating a climate for action, although many of us see this as a problem for regulators, and for others, rather than for each of us.

    Manufacturers must put resources and expertise into technical improvements for both diesel and petrol engine emissions. However, their abject failure on this over two to three decades is not a good omen for any major solution in the short to medium term.

    Regulators can reverse the fiscal advantages of diesels, which will encourage greater use of the more flexible and less polluting petrol engines, but at the price of climate change gases.

    Hybrid technology should be encouraged. However, if we really want clean cities we will have to move away from the internal combustion engine entirely. This means electric cars should become the only transport supported in our cities. The state of Ontario in Canada has introduced a five-year plan to convert to electric cars, including by subsidising new electric cars by a massive $14,000 each. Norway has only five per cent electric cars today but its transport minister says it is realistic to end the sale of fossil fuelled cars by 2025.

    Perhaps we should follow these leads now that we can set our own goals and subsidies.

    It will require initial funding, which perhaps could be kick started by massive (bank-style) fines on Volkswagen and other miscreants. As with solar-generated electricity, these subsidies can be withdrawn as the market matures and associated infrastructure becomes widely available.

    In addition to moving to low- or zero-emission vehicles we must all shift our thinking. We must walk more, bicycle, and use public transport. It is no use moving schools to less polluted streets: pollution comes with the school run. All of us must insist on pollution-free streets and cities in which we feel safe to walk, run, or bicycle to school with our children, go to the shops, or to work.

    Professor Sir Malcolm Green is the founder of the British Lung Foundation. From 1975 to 2006 he was a respiratory physician at the Royal Brompton Hospital