September 9, 2019

Guest Post by Ione Avila-Palencia

Addressing threats to urban air quality can bring together disciplinary perspectives which differ in their emphasis and considerations. In August, DrexelNow featured a conversation with Pete DeCarlo, PhD, about Philadelphia Air Quality, also published in the News section of Drexel University College of Engineering. The conversation is framed within the context of the recently closed Philadelphia Energy Systems refinery. As a researcher with an environmental and public health background, I aim through this post to complement and enrich certain ideas that DeCarlo expressed during the conversation, specifically: air pollution limits, transport policies, and energy generation.

Philadelphia’s air quality was noted by DeCarlo as ranked 18th or better in comparison with other US cities depending on the pollutant in question. From a public health point of view, I would also like to know how a city is doing in terms of accomplishing the air pollution limits set by relevant national (Environmental Protection Agency, EPA for the US) and global (World Health Organization, WHO) guidelines. Of course, our aspiration should not only be to accomplish these limits and guidelines, as there are still health effects even below them. For example, two meta-analyses found that per each 10 µg/m³ of PM_2.5 (the actual WHO recommendation), the risk of having lung cancer increases 9%; and per each 10 µg/m³ of NO₂ (the WHO recommendation is set on 40 µg/m³), the risk of having lung cancer increases 4%. Anyhow, from a risk communication perspective, there is value both in citing official guidelines and in discussing their limitations.

Beyond identifying levels of exposure, the important question of “How can we improve our air quality?” is raised. As DeCarlo highlights, one of the most important air pollution sources in cities is transport. For that reason, one of the most important actions to do in order to reduce air pollution in cities are transport policies. From an environmental and public health point of view, our focus on prevention favors elimination or reduction of emissions sources, which in our case scenario importantly includes cars. Even with a shift from combustion engines to more efficient, hybrid, or electric models the total particle emissions from vehicles will be non-trivial, due to particulate matter from brakes, tires, clutch, and road surface wear. Electric cars also have effects on other areas beyond the streets traveled, as mineral extraction and battery production contributes to pollution. We should not forget that one of the biggest extraction sites for cobalt (one of the main batteries components) is located in the Democratic Republic of Congo, where workers include vulnerable populations (e.g., minors) and experience conditions which would not be allowed in the US or across the European Union. This separation of where the costs are born from where consumption takes place creates environmental justice concerns. Furthermore, shifting towards electric cars will not end car-associated problems like sedentary lifestyles, social isolation, public space occupancy (with the consequent displacement of other uses), and traffic congestion.

A key approach to both urban air pollution and other urban health-related problems (e.g. noise, heat island effect, lack of physical activity, lack of green space, etc.) is to promote active transport (i.e. walking, cycling, and their combination with public transport). Prior literature, including work by investigators at the Urban Health Collaborative, links active transport with health benefits like better cardiovascular health, lower body weight, diabetes prevention, and also with more social interactions and better mental health. Some of the most important active transport determinants are residential density, walk/bike-friendly social environment, an environment perceived as safe by pedestrians, and the presence and well-maintained infrastructure like sidewalks and bike lanes. Regarding to public transport specifically, as DeCarlo mentioned, public transport infrastructure improvements are needed to promote wider use. In addition, policies like integrated public transport rates (i.e., allowing passengers to use all the public transport modalities within the city or metropolitan area – buses, subways, local railways, ferry boats, etc.- by buying only one ticket and not paying extra for any transport mode change) can encourage the use of public transport through all the different socio-economic positions.

The last topic I wanted to mention is the energy generation. In the conversation, DeCarlo says: “ […] if you talk about generating electricity cleanly—and I include nuclear in that as a possible clean or non-fossil source […]”. With the long-term perspective and precautionary principles typical of public health, we note that nuclear plants generate radioactive wastes which stay active for a long time. Challenges of safe storage and management are reduced but not eliminated by the use of technology and very strict safety protocols. In the case of an accident, potential environmental and health damage remains huge. The 2011 disaster at the Fukushima Daiichi Nuclear Power Plant, triggered by a strong earthquake and tsunami, provides a recent example. Other energy sources labeled as clean and renewable should be our main priority, as they do not carry the same risk and can also be planned taking into account a more local approach.

To summarize, air pollution is one of the multiple problems of a complex system: the city. Therefore, the solutions need complex system thinking. We should go further than just thinking about having less congested traffic or changing the technology used for transport. We should re-think how we want to move and in what kind of city we want to live, having in mind all the potential environmental and health risks and benefits of each alternative. Such challenges are being taken up by the Planetary Health movement, which is focused on the sustainability of our civilization and the impact of inequitable, inefficient, and unsustainable resource consumption on the planet and human health. To advance our understanding of this complex scenario and to find the best solutions, the exchange of ideas and collaboration between disciplines are needed more than ever.

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