By Rebecca Florsheim, Neil Vora, Peter J. Winch, and Connie Hoe
July 17, 2026
As wildfires continue to rage across Canada, blanketing vast swathes of the landscape in flames, a thick haze of smoke has descended upon cities across the United States, pushing air quality to hazardous levels. In New York City, the immediate impact was stark: emergency room visits for asthma exacerbations surged by an alarming 31% within the first day of the smoke’s arrival. This acute health crisis arrived at a particularly vulnerable moment, coinciding with the city’s second major heat wave of the season, compounding the physiological stress on its residents.
These extreme weather events are not isolated incidents but rather symptoms of a deeply interconnected and cyclical relationship between human activities and the environment. The combustion of fossil fuels fuels a warming climate, which in turn exacerbates natural disasters. These disasters, in their wake, generate a spectrum of related illnesses, creating a feedback loop of environmental degradation and public health challenges. While the escalating severity of such events can lead some to view the climate crisis as an insurmountable foe, history offers a crucial lesson: environmental health crises, however dire, can and should serve as catalysts for transformative change. By examining past public health emergencies driven by environmental factors, we can glean invaluable insights to inform our present response to the climate crisis.
The Shadow of Smog: A Precedent for Air Quality Regulation
The current crisis, driven by wildfire smoke, echoes a past environmental threat that once choked industrialized cities: air pollution. In the post-World War II era, long before the specter of global warming loomed large in public consciousness, cities grappled with unprecedented levels of atmospheric contaminants. At that time, regulations governing air quality were virtually nonexistent. The common practice of incinerating waste rather than transporting it to designated landfills, coupled with the widespread adoption of automobiles and the reliance on coal as a primary energy source, created a toxic cocktail in the air. The absence of meaningful emission standards meant that cities were frequently enveloped in dangerously polluted air, with soot and particulate matter becoming ubiquitous, settling on cars and windowsills as a grim testament to the degraded environment.
Scientists at the time began to identify specific components of this airborne menace. Substances like carbon monoxide, particulate matter, ground-level ozone, sulfur dioxide, and nitrogen dioxide, now categorized by the World Health Organization as "classical air pollutants" and by the U.S. Environmental Protection Agency as "criteria air pollutants," were found to have distinct health risks directly correlated with their chemical properties. Despite growing awareness of these dangers, effective regulatory measures remained elusive for decades, hampered by economic interests and a lack of public urgency.
The Great Smog and Its Aftermath: A Turning Point
The tipping point for meaningful air quality regulation arrived only after a series of increasingly severe smog events gripped cities worldwide. These events, characterized by stagnant atmospheric conditions trapping pollutants, turned the air a sickly bronze hue and led to a sudden surge in illnesses and deaths among urban populations, primarily from respiratory and cardiovascular conditions.
The Great Smog of London in December 1952 stands as a stark historical marker. This infamous event persisted for five days, during which an estimated 4,000 to 12,000 people died prematurely, with tens of thousands more falling critically ill. The sheer scale of the tragedy galvanized public opinion and directly precipitated the passage of the Clean Air Act of 1956 in the United Kingdom, which introduced crucial regulations to curb industrial emissions.
A similar, albeit later, crisis struck New York City in November 1966. The city experienced its most alarming smog event on record. As levels of sulfur dioxide and carbon monoxide soared, authorities took the unprecedented step of appealing directly to citizens through television, radio, and print media, urging them to reduce energy consumption and automobile use. Individuals with pre-existing heart or lung conditions were strongly advised to remain indoors. As municipal incineration services were temporarily suspended, garbage began to accumulate throughout the city, further contributing to the atmospheric degradation. The irritating and inflammatory nature of the smog left hundreds of thousands of New Yorkers struggling to breathe or experiencing exacerbated symptoms of underlying heart disease. Tragically, an estimated 200 people lost their lives during this event.
The Dawn of Environmental Legislation
The 1966 New York City smog tragedy served as a powerful catalyst, igniting public demand for environmental stewardship and prompting swift legislative action. Within a month, the New York City administrative code was amended to enhance air pollution surveillance capabilities and implement stricter emission controls. The extensive media coverage of the event resonated deeply with vulnerable urban populations across the nation, highlighting the pervasive threat of air pollution.
This heightened public awareness and political will culminated in a landmark special message to Congress by President Lyndon B. Johnson in January 1967. Titled "Protecting Our National Heritage," the message directly referenced the New York City smog event and advocated for the passage of the Air Quality Act of 1967. This act established procedures for abating air pollution. Building on this foundation, the landmark Clean Air Act of 1970 was enacted, setting National Ambient Air Quality Standards for criteria air pollutants, the very substances responsible for the smog and associated illnesses. The impact of this legislation and its subsequent amendments has been profound. By 2020, collective levels of criteria pollutants had decreased by an impressive 78% compared to 1970 levels, with some individual pollutants seeing reductions of as much as 91%. This legislative success meant that local emissions no longer posed the threat of widespread smog events in the U.S.
Bridging the Gap: From Criteria Pollutants to Greenhouse Gases
It is crucial to understand that criteria air pollutants, while distinct, are inextricably linked to greenhouse gases – the primary drivers of global warming. Both categories of pollutants, including carbon dioxide, methane, nitrous oxide, and tropospheric ozone, originate from the combustion processes that are fundamental to modern industrial and societal functioning. However, the pathways through which they inflict harm differ significantly.
Criteria air pollutants exert their detrimental effects directly on human health due to their physical and chemical properties. They can cause a range of immediate and chronic illnesses, including sinus inflammation, lung and heart disease, cancers, and ultimately, premature death. Greenhouse gases, on the other hand, contribute to illness less directly. Their primary impact is through the gradual warming of the planet, a phenomenon that then leads to a cascade of adverse health outcomes. A warming climate exacerbates a multitude of health risks, including direct injuries from increasingly frequent and severe extreme weather events, an increase in allergen-inducing pollen seasons that exacerbate respiratory conditions, the heightened risk of smoke inhalation from wildfires, and the accelerated emergence and spread of infectious diseases as ecological balances shift.
The Climate Crisis as a Tangible Health Threat
More than five decades after the passage of the foundational Clean Air Acts, the United States and the world are confronting another pressing environmental crisis: climate change. The increasing frequency and intensity of natural disasters – wildfires, hurricanes, floods, heat waves, and droughts – have transformed climate change from an abstract scientific concept into a palpable reality for hundreds of millions of people. Even those not directly impacted by these catastrophic events are now experiencing their indirect effects. The migrating haze from Canadian wildfires, blanketing major U.S. metropolises, serves as a poignant example of this interconnectedness.
The scientific evidence underscores the growing public recognition of this threat. Pew Research Center data from August 2025 indicates that 67% of individuals surveyed across 25 countries perceive climate change as a major threat. Furthermore, over 80% of Americans who have personally experienced extreme weather events acknowledge climate change as a contributing factor. Research also demonstrates that individuals who have directly endured extreme weather are more than twice as likely to view climate change as a crisis compared to those who have not. This lived experience, the tangible impact on their lives and communities, serves as a powerful, albeit often tragic, educator.
Leveraging Health Impacts to Drive Climate Action
The current environmental health crisis, marked by wildfire smoke and escalating extreme weather, presents a critical opportunity. Every extreme weather event, and its underlying cause in climate change, must be brought to the forefront of public discourse. Highlighting the direct health risks and associated economic costs of these events is a particularly effective strategy for engaging and motivating individuals who may harbor skepticism towards climate science. The causal link between these health impacts and the warming climate must be communicated clearly, consistently, and unequivocally, every single time.
Drawing parallels with the successful public health campaigns and legislative victories of the past, particularly in addressing air pollution, offers a roadmap for action. The public outcry and political will generated by the Great Smog of London and the New York City smog event of 1966 demonstrate the power of visible, tangible health crises to drive societal change. By framing climate change through the lens of public health, emphasizing its immediate and personal consequences, we can foster a broader understanding and a stronger impetus for action.
If we commit to this approach, learning from the lessons of past environmental health emergencies, this current period of alarming escalations in climate-fueled disasters could ultimately be remembered not just for its challenges, but for how we harnessed these crises to secure a more sustainable and healthier future for generations to come. The science is clear, the health impacts are undeniable, and the historical precedent for decisive action in the face of environmental threats is well-established. The time for comprehensive and sustained climate action, informed by the stark realities of our environment and its impact on human health, is now.
Rebecca Florsheim is an environmental health physician at the NYU Grossman School of Medicine. Neil Vora is a physician and executive director of Preventing Pandemics at the Source. Peter J. Winch, M.D., M.P.H., develops and evaluates interventions to promote health behaviors for water, sanitation, infectious diseases, and environmental sustainability. Connie Hoe is a public health researcher who serves as endowed division head for policy and implementation research at the German Cancer Research Center and as adjunct associate professor at the Johns Hopkins Bloomberg School of Public Health.
