The Air in Big Cities
Today, more than half the worldâs population (55 percent) live in cities (Ritchie and Roser, 2018). By comparison, in 1960, only about one-third of the worldâs population lived in cities. Researchers studying the mass migration of populations from rural to urban areas predict that two-thirds of the worldâs populations will live in urban areas by 2050.
People living in cities tend to have higher incomes than those in rural areas, which results in lower levels of poverty (Robison, 2019). However, one of the costs for this benefit is dirtier air breathed by city dwellers.
In an effort to reduce fuel consumption and CO2 emissions from vehicles in the 1990s after the Kyoto Protocol climate change agreement was signed in 1987, governments in Europe encouraged vehicle manufacturers to produce and sell more vehicles with diesel engines (Sullivan et al., 2004). As a result, Europe embraced the diesel engine. Until the mid 1990s, diesels accounted for less than 10 percent of the car fleet in Europe, but in 2015 they accounted for more than half of the car fleet (Vidal, 2015). Across the EU, there are more than 50 million diesels â compared to 1.6 million in 1998 (Robison, 2019). Only 7 million diesels are registered in the US.
While diesels produce 15 percent less CO2 than gasoline or petrol engines, they produce 22 times the particulates (which penetrate the lungs, brain and heart). A secondary pollutant â ozone â forms when these pollutants react with sunlight. Diesels also emit four times more nitrogen dioxide (NO2) which inflames the lungs, heart and brain, and appears to be a contributor to cancer, dementia, as well as respiratory illnesses (McCarthy, 2018).
For years, concerns about climate change overrode the concern about air quality among environmental groups, and government and businesses. Auto manufacturers produced more diesels from the mid-1990s, while governments kept the diesel price below that of petrol. In the UK, France and Germany, owners of autos emitting lower amounts of CO2 paid lower taxes â thus, these government incentivized citizens to buy more diesels. Diesels comprised 32 percent of new vehicle sales in 2018 in the UK (down from 50 percent in 2014) (Statista, 2020).
In 2015, researchers at West Virginia University in the US conducted independent tests of vehicle emissions and found evidence that diesels made by Volkswagen AG spewed 40 times more NO2 than in regulatory lab tests. Volkswagen later admitted it had intentionally created software to show its autos met emission standards (McCarthy, 2018). Volkswagen AG has paid $33 billion in fines and settlements. However, in subsequent research, Adac â Europeâs largest motoring organization â showed that diesel cars from Renault, Nissan, Hyundai, Citroen, Fiat, and Volvo released more than 10 times the level of NO2 than shown in tests conducted by the EU (The Guardian, 2015).
Now, the harmful effects of NO2 and particulates are more evident. Doctors now are confronting the need to educate patients about the dangers of air pollution similar to how they did for smoking cigarettes (Robison, 2019). A study conducted by the research consultancy CE Delft for the European Public Health Alliance in 2018 asserted that diesels accounted for 83 percent of the âŹ66.7 billion costs of air-pollution from traffic (both health and nonhealth) in the EU in 2016 (CE Delft, 2018).
Since 2015 when Volkswagenâs rigging of emission tests became known, dieselsâ share of new car registrations across Europe has dropped markedly from 50 percent to 36 percent (McCarthy, 2018). (By comparison, only 3 percent of cars in the US were diesels in 2015 (Chambers and Schmitt, 2015).)
Twenty-four European cities have adopted diesel bans that will go into effect by 2030 (Behrmann, 2019). For example, diesels will be banned from Paris and Madrid in 2024.
