In 2015, consumers were stunned by revelations that both Volkwagen and Audi had used hidden software to deceive American regulators who measure pollution emissions. The cars involved burn diesel. Compared to gasoline, diesel is a petroleum distillate containing more carbon atoms per molecule. The latter is burnt at higher temperatures, leading to more fuel efficiency. Although higher temperatures lower carbon dioxide emissions, they also facilitate the reaction between nitrogen and oxygen in the engine, leading to more of the type of pollution that causes smog and acid rain. This is where the scam kicked in; the cars were programmed to meet the nitrogen oxides (NOx) limit only when they were being tested. At any other time, they emitted about 40 times as much NOx. And even without the rigging of data, the larger carbon molecules in diesel lead to the production of more fine particulate matter (PM2.5) pollution.
1. Car Passenger Mortality
Cars are massive. Also kinetic energy is proportional to the square of their speed, which is part of their allure. Drive twice as fast and you need about four times the braking distance. Fail to stop and your collision will have four times the energy. Ensuing deaths seem to be an accepted fact of life which rarely raises an eyebrow unless it affects immediate family members. The truth is cars have a higher per passenger mortality rate than trains, buses and commercial aircraft. The mortality rate from car accidents in the United States is double their homicide rate. Critics will point out that the former rate has been declining since the 1970s, but this is only due to demographics. Due to aging baby boomers, there has been a decline in the proportion of inexperienced drivers (and hormone levels!) on the road. But such patterns are not present in places like India or Nigeria, and if those countries repeat our mistakes and rely heavily on driving, it will cost them many more lives annually.
2. Contribution to Climate Change
Cars using gasoline burn a mixture of heptane and octanes, compounds containing carbon and hydrogen. Oxidize such compounds and, among many other things, CO2 will be generated. Since there is no practical filter for carbon dioxide, all emissions end up in the environment, where they contribute to climate change. The U.S has about 250 million vehicles for its population of 320 million. China has 1.3 billion of the world’s 7 billion residents, but only 100 million or so vehicles. If ownership in China were to equal the U.S. rate, the Chinese would own over 1 billion vehicles, which would further amplify the greenhouse effect.
3. Contribution to Smog and Acid Rain.
We previously mentioned how cars form nitrogen oxides. These lead to nitric acid formation by reacting with hydroxyl radicals in the air. Nitric and sulfuric acids are the two major components of acid rain.
Nitrogen oxides also dissociate in sunlight to form ozone, a compound which is useful in the stratosphere. The problem is that it never gets there. Instead it remains at ground level where it is poisonous. In addition, nitrogen oxides react with hydrocarbons in the air to form peroxyacyl nitrates (PANS), constituents of smog. Although catalytic converters attempt to reverse the oxidation of nitrogen, they are not 100% efficient, so cars equipped with such gadgets continue to contribute to both acidic precipitation and smog, both of which claim the lives of those who suffer from respiratory diseases.
4. Cars Reshape the Urban Environment
As citizens become excessively dependent on automobiles, an exaggerated amount of land is devoted to those archaic 19th century inventions. The environment loses green spaces and public squares to highways and parking lots. The latter affect a city’s microclimate. Asphalt absorbs solar energy, raising already uncomfortable summer temperatures in urban centers, leading to more air conditioning, which releases more greenhouse gases.
5. Cars Contribute to Heart Disease and Type 2-Diabetes
People over-depend on automobiles to get around. They do away with walking, cycling or cross-country skiing. This lowers their physical activity, raises blood sugars and weakens their cardiovascular system. As the number of cars in the “developing” world increases, and as non-traditional diets are adopted, the world’s half billion cases of type 2 diabetes and the frequency of heart attacks will not get any smaller.