Wildfires and health

For a wildfire to start there are three essential requirements: fuel, oxygen, and an  ignition source, referred to as the fire triangle.


Projections indicate that the risk of wildfires will continue to increase in most areas of the world as climate change worsens.

Wildfires can further accelerate climate change, owing to the resulting greenhouse gas admissions and forest loss.

Wildfires will increase mortality, mobility, wild fire smoke, and mental health effects.


Greenhouse gas emissions and forest loss from wildfires a likely to accelerate climate change and possibly lead to a reinforced feedback loop.


Climate change related rainfall anomalies can intensify drought in tropical and subtropical areas. 


Rainfall is becoming more concentrated in winter, making other seasons, especially summer, hotter and dryer.


During dry periods there is an increase in the evaporation of moisture in soil which can lead to an increase in flammable vegetation they can fuel wildfires.


Global surface wind speeds have increased in the last decade, and is driven by ocean atmosphere oscillations, which may be related to climate change.

Residual smoke from wildfires can affect people even long distances from a burning area.

The hotter the fire burns, the greater the chance of a larger smoke plume and more likely that smoke will rise higher and travel farther:a plumes journey also depends on wind patterns and speed.

Wild fire, smoke can travel up and destroy the ozone layer, and after rising into the stratosphere smoke can stay up for months.

Climate change enhances differences in temperature between the land and the sea with a greater land-sea differences in air pressure, which boost wind power in tropical and southern sub tropical regions. 

Currently, the countries in sub-Saharan Africa, and South East Asia, experience the highest mortality rates from wildfire smoke.

Strong winds provide more oxygen for wildfires, encourages their spread, and potentially outstrips fire fighting abilities.


Another ignition source with climate change is lightning strikes.


The increases in the frequency and intensity of heat waves occurring under climate change provides more ignition sources for wildfires. 


Climate changes can affect lightning strikes, another important fire ignition source.


Due to the warming of the climate, wild fire season is starting earlier and ending later.


There is a narrowing of the window for prescribed burning, the deliberate  burning of available vegetation during cooler seasons to reduce the risk of wildfires.


The global area of land burned by wildfires have declined by approximately 30%, due to fire suppression and conversion of savannas and grasslands to agricultural lands.


The land burned in dense forests however, has increased.


Deliberate setting of fires to convert forests to open lands contributes to climate change with the  association of large emissions of greenhouse gases and air pollutants.


The risks and severity of wildfires in forests and the area of land burned are expected to increase in the future.


Previous estimates of carbon dioxide emissions from wildfires equated to approximately 22% of the carbon emissions from burning fossil fuels. 


Forest loss in tropical areas due to wildfire damages damages the Earth’s ability to absorb carbon dioxide and to cool the climate.


Wild fires in the Arctic forest system melts the permafrost and leads to release of previously frozen carbon and methane, which is a stronger greenhouse gas than carbon dioxide.


Wildfire health risks include exposure to fire and risk from wildfire smoke.


Wildfire health effects include burns, injuries, mental health aberrations, and death to exposure to flames or radiant heat.


Firefighters are at higher risk for heat related illnesses such as dehydration and heatstroke.


Individuals who undergo  traumatic experiences from wildfires including property loss, mental illness, post traumatic stress disorder, depression, insomnia. 


Psychological consequences of such stress can persist for decades, with children and adolescents being particularly vulnerable.


Childhood exposure to a wildfire is associated with increased mental illness in adulthood and decreased academic performance.


Exposure to wildfire smoke can cause eye irritation, corneal abrasions, reduce visibility, and increase the risk of traffic accidents.


Wildfires smoke increases ambient air pollution,  along with risks of illness and death.


Wildfire smoke air  pollution particulate matter consists of: carbon monoxide, nitrogen oxides, and volatile organic compounds.

Particulate matter in smoke can travel, hundreds of miles away.

Fine particulate matter particles are  2.5 µm or less in diameter, makes up about 90% of wildfire smoke’s , total particle mass.

Ozone can be generated as a secondary pollutants with a reaction between volatile organic compounds and nitrogen oxides under sunlight.


Peat fires can result in higher levels of air pollution with high emissions of carbon dioxide, and other toxic compounds, such as formaldehyde and hydrogen cyanide.


Wild fire pollutants of public health concern include carbon monoxide, ozone, and particulate matter.


Wildfire smoke is an increasingly important source of ambient air pollution.


There is a consistent association between the level of particulate matter during wildfire events and the risk of death from any cause or non-accidental death.


Wildfire particulate matter tends to have smaller particle size, and contains more oxidative components and  pro inflammatory components that potentially lead to stronger toxic effects, than urban particulate matter which comes mainly from combustion of fossil fuels.


The high temperatures associated with wildfires and oxidant gases of nitrogen dioxide and ozone can amplify the health risk of wildfire particulate matter.


Wildfire particulate matter is associated with an increased risk of respiratory events, impaired lung function, hospitalizations, emergency department visit, physician visits, and medication use for asthma, COPD, and respiratory infection.


Wild fire particulate matter has the strongest and most consistent relationship with the risk of asthma related events.


Studies suggest wildfire particular matter exposure have a stronger affect on asthma related events than exposure to urban particular matter as a result of more abundant oxidative and pro inflammatory components in wildfire particulate matter.


Wildfire particular matter exposure in the elderly is associated with increased cardiovascular adverse events.


Wild fire particular particulate matter is associated with adverse pregnancy outcomes with low birth weight and preterm birth, increased rates of influenza, increased ambulance dispatches for diabetes.


Wildfire events associated with potential carbon monoxide poisoning for residents and firefighters, and a secondary pollutant ozone can travel much farther under these conditions.


Individuals who have exposure to wildfire smoke have poor results for lung capacity, general health, and physical functioning than those who have not been exposed: 10 year data from Indonesia.


Individuals who are particularly vulnerable to adverse effects of wildfire smoke include: people 65 years of age or older, those with increased risk of short-term respiratory events, patients with pre-existing cardiac or respiratory conditions, people living in low income areas, pregnant women, and outdoor workers.


Children may be a greater risk to harm from wildfires based on their less mature respiratory and immune systems, increased breathing rate relative to body size, and more time spent outdoors.

Pregnant women and newborns are particularly vulnerable to the health harms associated with wild fires.

Wildfire smoke results in exposure to toxic gases, volatile organic compounds, and particular matter.

Pregnant patients exposed to wildfire smoke have an increase of gestational hypertension and gestational diabetes.

Exposure to wildfire smoke is associated with increased risk of preterm birth and low birth weight neonates.


Wildfire ash containing aromatic hydrocarbons and heavy metals can possibly pollute water reserves and land and must be managed.


In areas affected by wildfires water supplies that could be contaminated by wild ash, fire retardant or damaged water pipes need to be evaluated.


It is projected that with high greenhouse gases emissions, the frequency of wildfires will substantially increase over 74% of the global landmass by the end of this century.


If climate change mitigation can limit global temperature increases to 2°C with 1.5°C above preindustrial levels, then 60 , or 80%, respectively,  of the increase in wildfire exposure could be avoided.

Incomplete combustion during wildfires generates not only fine particulate matter (particles with an aerodynamic diameter of ≤2.5 μm [PM2.5]) but also nitrogen dioxide, polycyclic aromatic hydrocarbons, volatile organic compounds, and trace metals.

These particles can travel long distances,53 potentially harming communities hundreds of kilometers away from the wildfire.

Although environmental regulations have led to a decrease in PM2.5 levels in the United States, wildfire-related PM2.5 levels have increased, particularly in the western states.















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