In-car pollution: the greater of two evils?

The internal combustion engine of vehicles is perhaps one of the most notorious sources of outdoor air pollution. For instance, in the USA, pollutants from vehicular emissions comprise 60% of total atmospheric pollution in the country[1]. However, in-car pollutants are seldom acknowledged at all, with many people perceiving the environment within the car to be a safe zone from dangerous air pollution “out there”. On the contrary, research highlights that in-car pollution is much more severe than outdoor pollution, especially as traffic congestion worsens in urban environments [2]. This is owing to how cars are not airtight environments, thereby allowing fumes from vehicles in the surroundings to enter through vents and accumulate inside. In fact, there is an added layer of complexity since opening windows to enhance ventilation may increase the risk of further noxious chemicals from the external environment entering the car.

This in-car pollution is an exhaust fume concoction comprising of particulate matter, carbon monoxide, carbon dioxide, and smaller amounts of sulfur dioxide and nitrogen oxide [3]. Additionally, the “new car smell” that people tend to celebrate is also a cocktail of harmful Volatile Organic Compounds (VOCs), the outgassing of which tends to increase in higher temperature environments [4].

As cities become more urbanized and traffic congestion worsens, one potential solution to mitigate the air pollution associated with combustion vehicles is to instead increase the proportion of electric vehicles (EVs) on the road. Research from Argonne National Laboratory showcases how EVs not only have zero tailpipe emissions, but even while accounting for greenhouse gas emissions associated with their manufacturing process, they still contribute lower emissions (Fig 1) as compared to gasoline cars [5].

However, the phasing out of internal combustion engines and a transition to EVs will require significant time to implement. In the meantime, younger children remain especially susceptible to the adverse effects of the aforementioned in-car air pollutants, which compromise their brain and cognitive development alongside cause breathing issues and asthma [6]. Research also shows that people walking and cycling along the same urban routes experience less air pollution than those who drive [7]. Consequently, immediate mitigation strategies for overcoming the adverse effects of in-car and outdoor pollution should promote alternatives to driving for both public health and environmental reasons.

References

[1] Emissions from combustion engines | World Problems & Global Issues | The Encyclopedia of World Problems. (2016). Uia.org. http://encyclopedia.uia.org/en/problem/136957

[2] Karanasiou, A., Viana, M., Querol, X., Moreno, T., & de Leeuw, F. (2014). Assessment of personal exposure to particulate air pollution during commuting in European cities—Recommendations and policy implications. Science of the Total Environment, 490, 785–797. https://doi.org/10.1016/j.scitotenv.2014.05.036

[3] In-Car Pollution: What Can You Do? | Carro Singapore. (2018, May 6). Carro Blog. https://carro.sg/blog/pollution-inside-cars/#:~:text=Vehicle%20exhaust%20fumes%20consist%20of

[4] Guo, R., Zhu, X., Zhu, Z., Sun, J., Li, Y., Hu, W., & Tang, S. (2022). Evaluation of Typical Volatile Organic Compounds Levels in New Vehicles under Static and Driving Conditions. International Journal of Environmental Research and Public Health, 19(12), 7048. https://doi.org/10.3390/ijerph19127048

[5] US EPA, O. (2021, May 14). Electric Vehicle Myths. Www.epa.gov. https://www.epa.gov/greenvehicles/electric-vehicle-myths#Myth1

[6] Brockmeyer, S., & D’Angiulli, A. (2016). How air pollution alters brain development: the role of neuroinflammation. Translational Neuroscience, 7(1). https://doi.org/10.1515/tnsci-2016-0005

[7] Carrington, D. (2017, June 12). Air pollution more harmful to children in cars than outside, warns top scientist. The Guardian; The Guardian. https://www.theguardian.com/environment/2017/jun/12/children-risk-air-pollution-cars-former-uk-chief-scientist-warns