Originally inspired by my dissertation research on the historical development of Mexico City’s persistent air pollution problem, this reflection took on a renewed sense of urgency after the three-day Intercontinental Terminals Company petrochemical fire in March, which occurred only eighteen miles from where I live and released 3.1 million pounds of chemical emissions into the commons.
Sensory perception is integral in our ability to identify and understand environmental disturbances. During extreme weather events, sights, sounds, and smells function as barometers for severity and magnitude: tornadoes sound like howling freight trains; hurricane rains feel like needles; volcanic eruptions carry pungent, sulfurous smells; and wildfires are betrayed by their orange skies. Combined with the immediate physical impacts of these violent encounters, this sensory data legitimizes disaster.
But what of those more elusive phenomena, like air pollution, for which sensory signals are often lacking or, worse yet, deceiving? When even the clearest day can mask hazardous air quality levels, somatic and sensory experiences obscure more than they reveal. Air pollution crises are at their most conspicuous when preceded by events like earthquakes or industrial plant explosions. At these junctures, ambient pollution becomes the catastrophe within the catastrophe, manifesting as a thick layer of toxic soot emanating from collapsed infrastructure or a billowing plume of dark smoke wafting for miles. Yet air pollution events reside largely outside the socially accepted parameters of disaster, especially when not tied to nature-induced cataclysms. What accounts for this differentiation and what is at stake in expanding the categories of disaster to include air emergencies?
Perhaps the most obvious reason for the exclusion of air pollution from disaster typologies is that bouts of bad air just don’t look the same as “traditional” disasters. Unlike sudden disasters, pollution crises unfold slowly, generally without a central climactic event or clear signs indicating a beginning or end. In this, they are most similar to the slow disaster of drought, whose lifecycles commonly span months or years. Furthermore, the health effects of chronic exposure to atmospheric contamination are delayed, rather than instantaneous, and frequently governed by politics and dictated by experts. In this second point, heavy pollution spells bear a resemblance to their rapid-onset counterparts. Historians of disaster have shown that, despite their relatively short trajectories, the social, economic, and ecological consequences of mega-storms take place throughout the long term. Likewise, over time, dirty air episodes exacerbate existing socio-spatial inequities, not the least of which includes disproportionate levels of exposure based on racial and class lines.
Another factor that accounts for the disassociation of pollution from disaster is the historical process of industrialization, which normalized congested skies as both condition and evidence of attaining modernity. The Industrial Revolution first advanced this connection via the image of the smoking chimney, which quickly became the universal emblem for progress. This symbol, a signifier of productive societies, was recycled worldwide well into the second half of the twentieth century. As nations industrialized, becoming air-conditioned and vehicle-laden in the process, the tainted air they produced sometimes grew visible. Most of the time, it went unnoticed. In the midst of it all, concern for environmental conservation, habitually portrayed as a hindrance to economic development, waned. It is this consideration that has fostered a deep-seated social apathy and skepticism when it comes to the realities of breathing polluted air, especially in the United States, where, according to one commentator, “[…] most Americans have no concept of what it is like to live in a heavily polluted city like much of the world […]”
The increasing politicization of climate change and air pollution’s inherent paradoxical nature—it is at once omnipresent and impalpable—profoundly shape societal responses to questions about the quality of the air we breathe. On the one hand, air pollution is so commonplace that, at least on the surface, it lacks the shock factor of, say, tornadoes or tsunamis. On the other, its excellent ability to escape detection can nearly camouflage its very existence. In the United States, cities like Denver and Missoula, widely marketed as some of the cleanest and greenest in the country, and cherished nature reserves such as Yosemite National Park regularly top the rankings of most polluted spaces in the nation. This shared experience of living in polluted environments is marked by a global tolerance for its accompanying health risks. Allergies, pink eye, asthma, and others are mere inconveniences more so than they are serious signs of the slow and silent ways in which air pollution compromises human health.
In response to these challenges, environmental historians can and should center air pollution in narratives of environmental change, paying special attention to the ways in which the evolution of air pollution crises intersects with different contexts and conditions of disaster. Interested historians need not be confined to the disaster paradigm privileged here; they can take other methods and explore myriad themes such as: the longer history of air pollution, going as far back as Ancient Rome or the Middle Ages; transnational or collaborative efforts to reduce air pollution starting in the last third of the twentieth century; the legal or political history of pollution abatement; and even the historical effects of pollution on animals across urban and rural landscapes. Collectively, these ventures demonstrate that air pollution is a historical phenomenon with deep and stubborn roots that often reaches disastrous proportions rather than a contemporary circumstance that, when out of sight, can easily be put out of mind.
 A recent and fascinating example is Christopher Church, Paradise Destroyed: Catastrophe and Citizenship in the French Caribbean (Lincoln: University of Nebraska Press, 2017).
 William Cronon, Nature’s Metropolis: Chicago and the Great West (New York: W.W. Norton, 1991), 211; Natalia Verónica Soto Coloballes, “El control de la contaminación atmosférica en México (1970-1980): tensiones y coincidencias entre el sector salud y los industriales,” 37 Dynamis (2017): 196-197.
 Harrison Jacobs, “I visited what’s possibly the world’s most polluted city, and realized Americans have no idea how good they have it,” Business Insider, December 29, 2018.
*Citation featured image: Library of Congress, Prints & Photographs Division, LOC–2016648756.