The Public Health Impact of Vehicle Exhaust 

An often overlooked externality of vehicular emissions is the damage they cause to public health. Although much attention is given to emissions’ influence on the climate, the aforementioned effects are also well worth considering. 

It is obviously impossible, for ethical reasons, to directly test the exact effects of exhaust on humans. However, it is absolutely certain that breathing it does cause damage. The question is: how much? To approach an answer to said question, we can begin by looking for causal links between exposure to gasoline constituents and impaired health. 

Gasoline contains many compounds that are indisputably toxic, the most pernicious of which are mono-nitrogen oxides (NOx), sulfur dioxide (SO2), carbon monoxide (CO), volatile organic compounds (VOCs), particulate matter, benzene, formaldehyde, and ozone. Some of the proven negative health outcomes, associated with the inhalation of these substances, are listed below: 

Carbon monoxide – Once inhaled, carbon monoxide binds to hemoglobin within the blood with an affinity 240 times that of oxygen. After binding, CO interferes with the blood’s ability to carry and release oxygen, which can create a state of oxygen deficiency in the tissues. An article in the Yale National Initiative stated that exposure to carbon monoxide has been linked to “visual impairment, reduced work capacity and mental dexterity, poor learning ability, nausea, headaches, dizziness, and even death.” 

Ozone – Though beneficial in the upper atmosphere, ozone can lead to inflammation of breathing passages, reduce the lungs’ working ability, and cause general chest pain. 

Sulfur dioxide – Released from diesel engines, sulfur dioxide constricts airways, which can be particularly problematic for asthmatics, the very young, and the elderly. 

NOx – The effects of NOx inhalation are similar to those of sulfur dioxide and ozone. 

Benzene and formaldehyde – Evidence suggests that these substances are carcinogenic, and can lead to birth defects and genetic mutations.

PM 2.5 and PM 10.0 – The PM stands for “particulate matter” and the 2.5 and 10.0 stand for the diameters of these substances as measured in micrometers. For reference, a micrometer is about 1/25,000 of an inch. Studies have linked PM exposure with exacerbated asthma, chronic bronchitis, and increased mortality from heart and lung disease. 

The fact that something contains a dangerous compound does not necessarily mean that we should be worried about it. After all, apple seeds contain a compound that degrades into cyanide if chewed, but you can eat plenty of them before suffering any adverse effects. Similarly, the fact that exhaust contains these dangerous compounds does not necessarily mean it is harming us in a significant way, but their presence should elicit a healthy amount of concern and clearly warrants further investigation. 

To gain a better understanding of the actual (as opposed to potential) effects of exhaust inhalation, it can be useful to assess the effects that the reduction of emissions have had on and human populations that were previously subjected to high levels of exposure, and to assess data from animal models. Three such studies of this nature strike me as very illuminating: 

The first, which was funded by the MacArthur Foundation, looked at the effects of installing E-ZPass tolling systems on premature births and birth weight. Unlike older versions of tolling technology, E-ZPass systems collect tolls without requiring cars to stop for payment. They thereby reduce levels of automobile emissions in the areas where they are installed. 

Here’s an excerpt: 

“Among families living within 2 kilometers of expressway toll booths, premature births fell by between 6.7 percent and 9.2 per- cent after the installation of E-ZPass tolling systems. The incidence of low birth weight fell by between 8.5 percent and 11.3 percent.”

The study went on to estimate that the installation of such open tolling systems could save hundreds of millions of dollars per year in healthcare costs. 

The next study found that the installation of emission-reducing tech on school buses led to significant increases in students’ scores on english tests, and less significant (but still noticeable) improvements in their scores math tests. 

Finally, this telling study does a great job illustrating the effects that emissions can have by using rats as a model organism. In it, rats who were exposed to a simulated mixture of emissions (that contained the pollutants found in vehicle emissions) experienced impaired memory, and exhibited signs of anxiety and depression. It seems very likely that these effects are also manifesting in humans exposed to actual emissions. 

While these studies do a good job illustrating some of the tangible effects of vehicular air pollution, they do little to describe the problem’s magnitude on a global scale. While doing so with perfect accuracy is impossible, The International Council on Clean Transportation recently released an excellent report which estimated that, in 2015, tailpipe emissions were responsible for a total of approximately 385,000 premature deaths. This number, along with the many physical and mental health issues that the exhaust is clearly creating, emphatically drives home the fact that something needs to be done to remedy the situation. 

In my mind, electric cars seem to be the most viable solution. They do not directly emit pollution into cities, and are usually more environmentally friendly than even the most fuel efficient gasoline automobiles, regardless of whether or not they are charged with electricity that was generated by nonrenewable sources. This is largely due to the fact that the energetic efficiency of even coal powered electrical plants far surpasses that of the internal combustion engines in cars. While car engines must be capable of rapidly changing RPMs, and stand up to the stresses of driving, stationary power plants can run at a constant optimal speed, and don’t suffer the efficiency losses associated with being designed for mobility and lightness. 

Of course, EVs powered by dirty energy will have some indirect impact on the environment; If more electricity is demanded from a coal powered grid, more coal will have to be burned. However, the emissions from coal plants are not released in city centers and, as mentioned previously, EVs are still better for the environment in nearly every case, than their gasoline powered equivalents. This fact is illustrated beautifully by the following diagram from the Union of Concerned Scientists showing the MPG a gas powered car would require to be environmentally equivalent to an EV…

Thankfully, electric cars are finally beginning to become a mainstream option. This increased popularity is probably due in large part to the notable savings associated with switching from a gas powered car to an EV (estimated to be a median of $770 per year for drivers in the U.S.) and the increasing availability of charging infrastructure. If you would like to make the switch, check out this list of every EV going on sale in 2020.