The fires ravaging Canada today are yet another warning about the impact of global warming on our daily lives. As Justin Trudeau puts it, "These fires are more frequent because of climate change", and "it's the presence of fine particles in the air that is worrying". Today, it seems essential for every country with vast forests to provide the tools and actions needed to protect people and the environment.
Worldwide fire situation and trends
Ravages in Canada in 2023
Since the beginning of May, impressive forest fires raged across Canada, starting in the west and ending in the east. Because of its geographical position, the country is more rapidly affected by climate change.
With almost 5 million hectares burnt (800,000 in Quebec), the pollution generated by fires extends as far as the United States. Today, smoke travels as far as Norway in low concentration.
In 2022, Brazil experienced unprecedented wildfires. The Amazon rainforest saw 630,000 hectares destroyed by fire. More than thirty thousand fires have been recorded, with consequences for human health, biodiversity, and climate at a global scale.
Fires in France and Europe in 2022
European forests also suffered significant damage during 2022, with almost 800,000 hectares burnt. In France, the summer of 2022 saw several impressive fires in the pine forests of the Pilat region (20,000 hectares scorched). Spain also saw numerous fires in 2022, with almost 300,000 hectares destroyed. Last May, the west coast was ravaged by a 12,000-hectare fire, which is now under control.
The mixture of fog and smoke ("smog") released by forest fires contains sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and tiny particles that are undetectable and invisible to the naked eye. We call them "PM 2.5 particles" because they have an infinitesimally small diameter of 2.5 microns (μm). While gases are hazardous when close to fires, particles can travel thousands of kilometers and affect individuals without them even realizing it.
Effects on human health
Smog particles are so tiny that they easily circulate throughout the body, penetrating the lungs, mucous membranes, and even the bloodstream.
The risks are more or less significant following the duration you spend in a toxic atmosphere and the quantity of smoke you inhale. Therefore, physically active people and workers operating outdoors are more affected by exposure to harmful substances from fires. Those most at risk are older people, children, pregnant women, and individuals with previous or current health problems.
The first symptoms that may arise from exposure to smog are headaches, dizziness, coughing, or irritation of the eyes, nose, and throat. In severe cases, asthma, stroke, or heart attack are possible.
Because smoke contains such a high concentration of various gases, the effects can vary from person to person. Here are details of the harmful effects of the different gases that make up forest fire smoke:
Colorless, it is composed of sulfur and oxygen (SO2). The gas is recognized by its strong, unpleasant, and suffocating odor.
It affects the respiratory and pulmonary systems, causing coughing, mucus overproduction, severe asthma, recurrent bronchitis, and susceptibility to respiratory infections. SO2 can also cause eye and mucous membrane irritation and skin and eye severe damage. In high concentration it can intensify respiratory illnesses in sensitive or afflicted individuals.
The acidity of sulfur dioxide is particularly harmful to the ecosystem. When SO2 is released into the air with water presence, it is transformed into sulfuric acid (H2SO4) leading to the formation of acid precipitation. Acid deposition damages architectural heritage, acidification of surface waters kills animal species and affects freshwater and marine food chains, and soils are depleted and degraded, with adverse effects on plants.
NO2 is particularly harmful to people with asthma as it primarily attacks the lungs. Long-term exposure, even at low concentrations, can cause respiratory problems, with coughing or wheezing, a symptom of a possible asthma attack. At high concentrations over a short period, an inflammation of the respiratory tract is possible.
Like SO2, nitrogen dioxide contributes to the phenomenon of acid rain, which weakens natural environments and contributes to the formation of tropospheric ozone (a colorless, irritating gaseous pollutant just above the earth's surface, created when two pollutants react to sunlight and stagnant air).
Colorless and odorless, carbon monoxide consists of a single carbon atom and a single oxygen atom (CO).
Carbon monoxide is one of the most dangerous gases for health, as it takes the place of oxygen in the air. It acts directly on the bloodstream, preventing the transportation of oxygen to vital organs such as the heart and brain. A person with low levels of CO exposure may experience signs of fatigue, nausea, or headaches. High intoxication rapidly asphyxiates the body and causes impaired judgment, confusion, loss of consciousness, convulsions, chest pain, shortness of breath, low blood pressure, and even coma.
CO contributes to the greenhouse effect: its oxidation transforms it into CO2 (carbon dioxide), which plays a significant role in climate change. It also contributes to the increase in CH4 (methane) and N2O (nitrous oxide), which increase global warming and thus hurt the ecosystem.
PM2.5 fine particles
The tiny particles emitted by forest fire smoke are a mixture of chemical compounds. They contain Black Carbon from the incomplete combustion of fossil fuels, primarily organic matter from volatile organic compounds emitted by human activity and vegetation, inorganic substances such as sea salts, and inorganic species such as nitrate, sulfate, or ammonium.
PM2.5 particles (diameter 2.5 microns - μm) released by combustion processes represent the majority of pollutants present in the atmosphere. Their size enables them to quickly penetrate the respiratory system, the lungs, and the bloodstream. They affect the neurological and cardiovascular systems and play an essential role in cancer development.
How to protect yourself from the smog?
During forest fires, scientists regularly calculate the concentration of the five pollutants (ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, PM2.5 fine particles) that compose the atmosphere to monitor air quality and inform the population if necessary.
Air quality is "poor" when the concentration of pollutants exceeds 35 micrograms per m3, with Canada reaching 266μg. When the smoke reached New York City, the American metropolis was awarded the prize for the most polluted city on June 07, with an air quality index of 80 instead of 50, which sets the limit for a good atmosphere.
To determine air quality, the researchers use portable detectors during their analyses, enabling them to protect themselves by being alerted to gas concentration thresholds and to define whether the atmosphere is breathable.
In the wake of the Canadian fires, the US government urges its citizens to bring out the masks used during the covid19 pandemic.
Scientists dread the aftermath, as the impressive harmful fine particles will remain in the atmosphere without being visible. The authorities want to anticipate this by equipping cities with the necessary equipment to protect the population.
Carbon monoxide is a good indicator of pollution levels. It has a lifetime of several weeks in the atmosphere, during which it can travel thousands of kilometers. Scientists can thus track the evolution of a pollution cloud over different countries or continents since CO emissions during forest fires are very high.