Harmful aerosol particles near and far

Right now, we are horrified by the idea of radioactive fallout. There are other harmful long-range transported aerosols as well, and we should protect ourselfs against all of them. The size of an aerosol particle determines how long it stays airborne and thus, how far it travels in the air. Size also determines how deep into our respiratory tract it penetrates. In addition, the size determines how easy or difficult it is to filter the aerosol out of the air.

One could say that the smaller the particle, the longer it stays airborne. This applies to the atmosphere, our respiratory system, or an air filter.

To be precise, there is actually a size that stays airborne most efficiently and smaller particles are again depositing faster. This size is about 0.1 micrometres (μm), which means 100 nanometres or a millimetre divided by 10 000. Small size does not make the aerosol any less harmful. The ultrafine size range causes adverse health effects and can even penetrate into our brains and cause Alzheimer's. Ultrafine particles are formed e.g. always when something burns and their number is highest very close to the combustion source.

Then why are the aerosol of a radioactive fallout or, for example, forest fires, worrying? In addition to the composition, of course. They are exactly the size that travels in the atmosphere for days, even weeks, reach deep into the respiratory system and require a proper filter to be removed from air.




One scientific publication reports Fukushima fallout studies from France, Austria, the Czech Republic, Poland, Germany and Greece. According to the study, majority of the radioactive particles were in the size range between 0.1 to 1 μm. The researchers further defined in which particle sizes certain radioactive isotopes were. The median size range for Cesium (137) was 0.25 to 0.71 μm, For Cesium (134)  0.17 to 0.69 μm, and for Iodine (131) 0.3 to 0.53 μm.

In addition to aerosol particles, radioactive fallout also contains radioactive gases. Iodine gas can be filtered with ordinary activated carbon (elemental iodine) or impregnated activated carbon (iodine compounds).

An air purifier with a HEPA filter significantly reduces the number of harmful aerosols in indoor air. HEPA filters are tested with the most penetrating particle size. There are several grades of HEPA filters, but even the lowest one filters more than 95% of the most penetrating particle size.

Many Lifa Air air purifiers also have an activated carbon filter.


Every year, landfires pollute air worldwide. The smoke is worse close but long-range transported pollutants are detected far from the fires. The particles of e.g. a forest fire do not sound as frightening as radioactive fallout, but the probability of inhaling them is much higher. All combustible particles are harmful and most of them are very small.

A well fitted FFP3 and an air purifier will limit your exposure to harmful aerosol particles

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Radioactive fallout:
Size Distributions of Airborne Radionuclides from the Fukushima Nuclear Accident at Several Places in Europe. Masson et al. Environmental Science & Technology 2013, DOI: 10.1021/es401973c

Health effects of ultrafine particles:
Particle size distribution of radioactive aerosols after the Fukushima and the Chernobyl accidents. Mala et al. Journal of Environmental Radioactivity, 2013, https://doi.org/10.1016/j.jenvrad.2013.07.016


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