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Up in Smoke: Wildfires Impact Human Health and Squeeze the Carbon Budget


By Dr. Dinah A. Koehler  |  July 25, 2023

In our house we have a new appliance: the HEPA air filter. Besides removing tiny airborne particles, it even tells us when to go to bed and switches to sleep mode with a gentle purr. Carefully monitored by my scientist husband, we compare outdoor and indoor air quality.

On June 6, the EPA's Air Quality Index (AQI in New York hit 272, considered “very unhealthy,” and New Yorkers were encouraged to wear masks outdoors. Two days later, the AQI soared to 900, unheard of territory.

Many of us on the East Coast found ourselves coughing, eyes stinging, and headachy. ER visits related to asthma reached an all-time high. Everyone shared pictures of a blood-orange sun in a greyish-pink sky, and the smell could at times be intense. Generally the mood was dour.

The winds finally shifted, but we on the East Coast now have an intimate appreciation of what our brethren in other Canada-adjacent regions of the US have experienced.

Why worry?

The latest science notes that even small amounts of air pollution can harm your health. For example, two hours exposure to common levels of urban air pollution from vehicles measurably impairs memory and attention. Just like air pollution from burning coal for electricity or burning gasoline to power cars, tiny particles (PM 2.5) in smoke can penetrate deep into lungs and enter bloodstreams to cause problems.

People of all ages are at risk of lung damage—especially those with asthma or cardiovascular disease, pregnant women, young children, and older individuals are at elevated risk. Indeed, young children (0-5 years) visit the ER 10 times more often after exposure to wildfire smoke compared with other air pollution.

The long-term effects of exposure to air pollution can reduce life expectancy. On average around the world, humans lose almost two years of life. Globally, one in five deaths is associated with pollution from fossil fuel combustion, totaling about 9 million people per year. About 5.5 billion people (75% of humanity) live in high air-pollution areas, with most associated deaths in India and China primarily due to heart attacks and strokes.


Wildfires Also Pressure Carbon Levels

We can expect additional implications as wildfires become more frequent and persistent. Along with other sources of air pollution, wildfires generate a lot of carbon dioxide (CO2), the force behind global warming.

Since May, Canadian wildfires released an estimated 600 million metrics tons of carbon dioxide—equivalent to 88 % of total Canadian CO2 emissions in 2021, according to the Copernicus Atmosphere Monitoring Service (CAMS). At this point wildfires are the largest source of CO2 emissions in Canada.

Scientists confirm that fires have become more common over the past 20 years and are burning hotter. The severity of fires and the length of the fire season are also rising fast. For example:

  • The 2020 wildfire season in California wiped out two decades of efforts to reduce CO2 emissions associated with fossil fuel combustion.

  • In 2021, one of the worst years for wildfires, forests equivalent to the size of Belgium were destroyed.

Most fires are in the boreal region of North America and Eurasia. Boreal forests store approximately twice as much carbon compared with tropical forests such as the Amazon. According to Steven Davis, UCI professor of Earth system science, “About 80 percent of these CO2 emissions will be recovered through vegetation regrowth, but 20 percent are lost to the atmosphere in an almost irreversible way, so humans are going to have to find some way to remove that carbon from the air or substantially cut our own production of atmospheric carbon dioxide.” 

We have reached the stage where ecosystem feedback loops due to climate change—when changes in one area “feed back” to either amplify or diminish the source—present material risks for our ability to stay within the 1.5 degrees-aligned carbon budget.


This blog post is for informational purposes only. The information contained in this blog post is not legal, tax, or investment advice. FactSet does not endorse or recommend any investments and assumes no liability for any consequence relating directly or indirectly to any action or inaction taken based on the information contained in this article.

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Dr. Dinah A. Koehler

Vice President, Head of ESG Research, FactSet

Dr. Dinah A. Koehler is Vice President, Head of ESG Research at FactSet. In this role, she is responsible for research on cutting edge ESG topics and thought leadership. Prior to FactSet, she has worked 25+ years in corporate sustainability, including at corporations (Baxter, Tetra Pak), US EPA in the Office of Research & Development, Wharton/UPenn, The Conference Board, Deloitte, and the Global Sustainable Equities Team at UBS Asset Management. She specializes in environmental risk analysis, regulatory data, life cycle assessment, and impact measurement. She is a seasoned speaker and has published in peer reviewed journals, books, and industry publications. Dr. Koehler earned her Science Doctorate at Harvard School of Public Health, a Masters from The Fletcher School at Tufts University, and a BA from Wellesley College.


The information contained in this article is not investment advice. FactSet does not endorse or recommend any investments and assumes no liability for any consequence relating directly or indirectly to any action or inaction taken based on the information contained in this article.