Each year, there are tens of thousands of individual fires that burn across the Amazon rainforest, a 6.7 million square kilometer river basin ecosystem that spans 8 countries and an overseas territory (1). Fires are usually intentionally set to clear land for cattle, soybean, and sugarcane production (2)(3). But they’re also increasingly flaring up because of severe heat waves fueled by climate change.

These fires, in addition to worsening wildfire seasons around the globe, have ignited renewed discussions of the major impact that wildfires have on climate change and to global air quality. Amazon wildfires have occurred during severe summer heat waves and are known to have contributed to a rise in average particle pollution levels in both their source countries and the United States.

The loss of a vast area of the Amazon rainforests contributes significantly to climate change. The Amazon, home to 10% of the world’s biodiversity and at least 15% of all its fresh water, has long been an enormously important feature of the planet’s ability to capture harmful carbon from the atmosphere and produce a large volume of the earth’s oxygen supply (4). For this reason, some have labeled the Amazon rainforests the "earth's lungs."

Amazon Rainforest Air Quality Stations

Air quality stations in and around the Amazon measure airborne particle concentrations increased by wildfires. There are dozens of air quality monitors located in the rainforest-dominated areas of Brazil, Bolivia, French Guiana, Colombia, Ecuador, Peru, Suriname, and Venezuela. But there remains a strong need for more monitoring across the region.

How far does wildfire smoke travel?

The reach of wildfire smoke is surprisingly vast. Even when fires burn thousands of miles away, their particulate matter can still be inhaled by people living far from the fire's origin.

As with any other wildfire, smoke in South American rainforests travels globally. Wildfire air pollution from the Amazon can travel as far north as Alaska and as far distant as Asia on the other side of the world.

Take the 2019 wildfires in Brazil as an example: Over 87,000 fires were recorded, significantly impacting air quality. A 2020 study in Geohealth revealed a startling fact – nearly 10% of Brazil's premature deaths that year were linked to smoke pollution (5). Such statistics underscore the critical need to understand and address the far-reaching impacts of wildfire smoke (6).

The vast spread of smoke from the Amazon fires illustrates this point. Propelled by a mix of the smoke's inherent properties and global wind currents, the smoke from these fires blanketed areas stretching from the western coasts of South America to Papua New Guinea and Australia, over 17,700 kilometers away, in just a matter of days.

Here’s how that happens:

• Smoke rises miles into the air due to a mixture of intense heat from flames and conditions in the atmosphere like sunlight, cloud cover, and wind speeds.
• Global wind currents blow smoke for hundreds of miles across the upper atmosphere and spread airborne pollutants for hundreds of miles in every direction. In the case of Amazon fires, the westward-blowing currents along the equator can take the smoke as far west as Australia, China, and Indonesia. Then, the smoke is blown northward by currents near Japan, and then eastward by north Pacific currents that bring that same smoke all the way to the United States, Canada, and Central America.
• Pollutants in the upper atmosphere react with heat from sunlight and lower-lying pollutants in major urban areas. Regions that produce a lot of industrial and traffic pollution are especially vulnerable to the added pollution that smoke can bring to the area – not only are nearby major urban areas like São Paulo in Brazil directly affected by Amazon rainforest fires, but cities as far-flung as Mexico City and as far north as Alaska and eastern Russia were affected mere days after the fires started.

How to defend against wildfire smoke

Wildfire smoke can be long-lasting and harmful to more than just the lungs – even just brief exposure can lead to heart attacks, arrhythmia, and respiratory infections (7). PM2.5 can be as much as ten times more harmful to human health than PM2.5 from other sources, according to a 2021 study published in Nature Communications (8).

According to study findings, respiratory hospitalisations associated with wildfire PM2.5 in Southern California between 1999 and 2012 ranged from 1.3 to up to 10 percent of cases as compared to 0.67 to 1.3 percent of hospitalisations for PM2.5-associated causes that were not during wildfires.

And research shows that wildfire seasons around the world are getting longer. A 2015 study published in Nature Communications found that there was a nearly 19 percent increase in global mean fire weather season lengths between 1979 and 2013 (9).

Here’s what can be done to help protect against wildfire smoke:

• Monitor the local air quality. In the hours or days following a wildfire, use an air quality monitor to see your current air quality and compare it to both historical and forecast data. Using an air quality monitor to view your daily air quality patterns can help you learn to discern any major changes that occur due to fires or increased levels of local pollutants like PM2.5 from traffic or industrial emissions.
• Watch worldwide air quality maps closely.In addition to monitoring your own local air quality, keeping up with world air quality trends can help you prepare for any events that may impact your air quality at home. Visit the IQAir Map page for a live air quality map that also shows how wind currents may carry the smoke beyond its source.
• Download the app. Get real-time air quality updates to your phone immediately with the free AirVisual app.
• Avoid going outdoors. Wildfire smoke can linger in your local air for days, weeks, or even months. Try to limit time spent outdoors to only essential activities, such as commuting or buying food and supplies. For individuals who are particularly sensitive to poor air quality, this is an especially important step to take.
• Wear an air pollution protection mask. If you must go outside, a simple dust mask or medical mask won’t do against wildfire smoke – they do nothing to filter out the tiniest and most harmful particles in smoke. Make sure you use a mask that’s at least certified KN95, N95, or FFP2. These masks filter out PM2.5 and quality masks can capture up to 95 percent of airborne particles as small as 0.3 microns, which may be found in dense concentrations in wildfire smoke. They’re designed for long-term use by reducing moisture and carbon dioxide (CO2) buildup inside the mask while also applying little pressure to the face and ears.
• Create a clean air safe zone indoors. When wildfire smoke is affecting your local air quality, close all your doors and windows to keep smoke from seeping in. Make sure to close the outdoor air intake on your HVAC system so that polluted outdoor air isn’t pulled into your indoor recirculated air. Use an air purifier for wildfire smoke capable of capturing all types of airborne wildfire pollutants, including PM2.5, carbon dioxide, nitrogen oxides, and thousands of other dangerous compounds.

The takeaway

Extreme Amazon rainforest wildfire events are increasing as temperatures rise around the globe. More intense fires and longer wildfire seasons may be the norm for the foreseeable future. With wildfires comes smoke and particle pollutants that can travel for thousands of miles beyond their source.

But equipped with the right tools, it’s possible to see when those pollutants will be most present and act to minimise wildfire smoke health risks.