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No smoke without micro particles – Wildfires are a serious health risk


Wildfires have caused major financial and human losses lately – and not just in California. A long dry season in the spring caused massive wildfires near Sydney and Melbourne and resulted in clouds of smoke that restricted visibility in the cities. Spending time outdoors was not recommended, because smoke contains micro particles that are dangerous for health.

In California alone, experts state that over 3,2 acres of land has burned down – and the wildfire season isn’t even over yet. This August Complex fire is in fact the largest wildfire in the history.

Why are wildfires so aggressive right now?

According to climate experts, climate change is visible in the frequency and duration of wildfires. Dry seasons are longer and hotter. From the 70’s until 2016 the average duration of wildfire seasons has increased from 105 days to 250 days, so it has more than doubled. (Climate Central). This has an impact to the surrounding areas’ particle levels and long-term exposure. 

Wildfires produce smoke gases, small particles and hydrocarbons in to the air

The University of Helsinki, Finnish Meteorological Institute and several other science facilities and universities (i.e. San Jose/California) made an experiment in order to study wildfire emissions in 2009. The experiment was done by lighting up a strictly limited area in the forest. The emissions were then studied on ground level, in moving objects in the area and from an airplane. The research concluded that an enormous amount of small particles are produced by wildfires. The small particle count was larger in the air above the area than on ground level and they were also carried away far from the source by wind. A sample taken from the cloud of smoke approx. 100-200 yards away from the fire was studied – the sample contained 2-4 million small particles per square centimeter, whereas typically the number is around hundreds or thousands of particles. Also a wide variety of VOC emissions were found, some of them harmful for health.


Another finding in connection with Australian wildfires was that fires raise large amounts of soil and carry it far from the fire areas.

Harmful small particles are carried over long distanced by wind

The air quality varies a lot near the wildfires based on wind directions. There are days when it is advised not to spend time outdoors. For example in various parts of Sydney, particle amounts ten times larger than the average were measured. On a peak day one could feel and see the smoke. The cities near the fire areas surpassed the annual safety limit (PM 2,5) by 78% during the fires in 2019/2020.


Air quality is measured widely all around the world and people can track their area’s air quality from dedicated web sites. While writing this article, the fires are still going on in California. At some point World’s Air Pollution: Real-time Air Pollution Index showed different results for example on Mammoth Lakes-Gateway HC area, varying from 641 (hazardous) to 188 (unhealthy). The residents in the area have been advised to wear a mask and stay indoors. The air quality is reported as both PM2.5 and PM10 concentrations on a scale of good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous. Local air pollution is also straining the results - not just wildfires.

Why it is important to track the small particle levels?

The small particles caused by fires and pollution are a health risk. The most dangerous particles are the ones we can’t see with human eye, like PM2.5 or PM10. We can see smoke and its larger particles, but studies show that the smoke also contains large amounts of these smaller particles we can’t see.


Exposure to small particle air pollution causes more serious health risks than all other environmental factors combined in the developed countries, writes Finnish Institute for Health and Welfare. When it comes to wildfires, the particle matter levels are usually highest in close proximity from the fire. Particles can be carried by wind for thousands of miles. Particles spread on a large area can also cause a significant public health risk.

Children and people with respiratory illnesses are especially sensitive for air pollution. Prolonged, repetitive harmful atmospheres can have unfavorable effects on health – for example body’s infection mechanisms. That is why the outdoor air quality matters. As we know that the micro particles and VOC gases will find their way indoors, it’s important to think about indoor air quality as well.

Keeping micro particles away from children’s breathing air

It is important to pay closer attention to air quality in schools and children’s daycare facilities – especially around wildfire areas. Even though the fire and smoke themselves are not a direct risk, the micro particles are. The dangerous small particles can be removed from indoor air efficiently with easy to use air purification technology that removes small particles in PM2.5 and PM10 range down to nanoscale, thus reducing exposure to small particles significantly. It is especially important on peak days when small particle levels can rise multiple times higher. Air purification can be used 24/7. The units go through the room's air mass approximately four times in an hour, producing breathing air free from small particles.



Los Angeles Times: The worst fire season ever 

YLE: Yhdysvaltain länsirannikon paloalue vastaa isoa kaistaletta Etelä-Suomesta - savu tuntuu sitäkin laajemmalla alueella, Seattlessa kehotetaan kaikkia pysymään sisällä. 

 Nasa -: Study: Fire seasons getting longer, more frequent

Ilmatieteen laitos: Metsäpalot tuottavat ilmakehään valtavat määrät pienhiukkasia 

NIH - Effects of bushfire smoke on daily mortality and hospital admissions in Sydney, Australia

Ansto - Fine particle pollution peaks during bushfires  

World’s Air Pollution: Real-time Air Pollution Index

Terveyden ja hyvinvoinnin laitos: Ilmansaasteet 




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