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Wildfire smoke is an underestimated threat to public health

In the wake of increasingly devastating wildfires, an eye-opening study has shed light on the alarming impact of wildfire smoke on public health and economic well-being. The research, published in the journal Science of the Total Environment, highlights the substantial toll that wildfire smoke takes on human lives and economic resources.

The study reveals that in the United States, smoke particulates from wildfires are responsible for an estimated 4,000 to 9,000 premature deaths annually. The economic repercussions are equally staggering, with an estimated cost ranging from $36 to $82 billion per year.

Wildfire smoke is an overlooked source of air pollution

Study senior author Oliver Gao, a professor of Civil and Environmental Engineering at Cornell University, suggests that wildfire smoke is a widely overlooked source of air pollution.

“We think of automobile tailpipes and factory emissions polluting our air,” said Professor Gao. “We don’t necessarily think about air pollution from natural sources like wildfires.”

Gao links the uptick in wildfires to climate change. He explains that the changing climate does not just result in more storms and hurricanes, but also creates favorable conditions for wildfires to thrive. 

Professor Gao pointed to the Quebec wildfires that occurred in early June as an example of how smoke from wildfires can have far-reaching effects on human health. They impact communities even hundreds of miles away in cities such as New York, Philadelphia, Baltimore, and Washington.

A major concern is the release of fine particulate matter, known as PM2.5, during wildfires. These particles consist of a mix of inhalable organic compounds, aerosols, and metals.

They have a diameter of 2.5 microns or less. This is significantly smaller than the width of a human hair. Such small particles can easily penetrate deep into the lungs and enter the bloodstream, posing serious health risks.

How the wildfire smoke study was conducted 

In order to quantify the effects of wildfire smoke, the researchers analyzed satellite wildfire emission data and air quality measurements (specifically PM2.5 levels) from 2012 to 2014. The study further broke down the potential impacts on human health and economies in different regions.

According to the research, metropolitan areas situated close to the sources of wildfires, such as Los Angeles, Houston, and Atlanta, are particularly vulnerable to both health burdens and economic losses.

The researchers’ model estimates that, for instance, New York City, which was recently affected by the Quebec wildfire, could experience 86 premature deaths from similar events with an accompanying economic toll of approximately $780 million.

The states that are likely to be most severely impacted, in terms of premature deaths due to the particulate matter carried in the smoke, are California, Florida, Texas, Georgia, Alabama, and North Carolina.

Mitigating the harmful effects 

However, Professor Gao emphasizes the significance of laws and regulations in mitigating the harmful effects of wildfires.

For instance, forest management practices such as thinning forests and creating green firebreaks can reduce the fuel available for fires. In turn, this substantially decreases the harmful effects of smoke in downwind populated areas.

“Wildfire affects our health,” said Gao, underlining the urgency of addressing this issue. “In this era of climate change, if we remove flammable vegetation and do things like create green fire breaks and reduce the fuel for the fires, we can substantially decrease the harm of smoke downwind in populated areas.”

The study serves as a call to action for policy makers, environmentalists, and the general public to recognize the multifaceted impacts of wildfire smoke. It also implores the public to work collectively to implement measures that can safeguard both human health and the economy.

Wildfire smoke: Health & climate

Wildfire smoke is a complex mixture of air pollutants that is produced when the organic material in trees and other vegetation burns. It contains both solid particles and gases. Some of the primary constituents of wildfire smoke include:

Particulate matter (PM)

The smoke from wildfires is rich in particulate matter. These are tiny particles that are suspended in the air. PM2.5, in particular, is a health concern as these particles are small enough to be inhaled deep into the lungs. They can cause a variety of health problems, such as respiratory issues, heart attacks, and strokes.

Carbon monoxide (CO)

This is a poisonous gas that is released when wood and other organic materials burn. In high concentrations, it can cause headaches, dizziness, and confusion. In very high concentrations, it can be lethal.

Volatile organic compounds (VOCs)

These are a large group of chemicals that include many different compounds, some of which can cause health problems. Some VOCs, such as benzene and formaldehyde, are known to be carcinogenic.

Polycyclic aromatic hydrocarbons (PAHs)

These compounds are released when wood and other organic materials are burned. Some PAHs are known to be carcinogenic.

Nitrogen oxides (NOx)

These gases are produced during combustion processes and can react with other substances in the atmosphere to create ozone and other pollutants.


While not directly emitted in smoke, ozone can be formed when nitrogen oxides and volatile organic compounds (both present in wildfire smoke) react in the presence of sunlight.

The effects of wildfire smoke can range from eye and respiratory tract irritation to more serious disorders, including reduced lung function, bronchitis, exacerbation of asthma, and premature death. Particularly at risk are individuals with heart or lung disease, older citizens, and children.

If a significant wildfire is nearby, it’s recommended to stay indoors, close all windows and doors, and set air conditioning units to recirculate to prevent outside air from moving inside. Those particularly at risk may need to relocate until the smoke subsides.

Wildfire smoke can also impact the climate. The aerosols in the smoke can have both cooling (by reflecting sunlight back to space) and warming effects (by absorbing heat), the net effect depends on the balance between these two. The black carbon or soot in wildfire smoke is a particularly potent warmer and can contribute to accelerated melting when it lands on snow and ice, darkening their surfaces.


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