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There are droplets and droplets

The COVID-19 pandemic has brought attention to what was already a long-standing problem linked to pollution: particulate matter.

Respiratory or not, many "particles" are suspended in the air around us: we need to think in microns, or micrometers, that is, one millionth of a meter.

There are sand particles of the most diverse origins - the “yellow” sky due to the sands of the Sahara, the deposits on our cars after intense rain,… - which are around 90 microns. Hair, dander, scales of skin - dandruff for example - the wool flakes of a blanket thrown against the light can be around 50-70 microns or more. With pollen, dust we move to 10 microns, the famous PM10. For comparison, a human red blood cell is typically around 8 microns. To go to combustion particles, metal compounds ... which are about 2.5 microns or less, the equally famous PM2.5. This <2.5 includes many of the viruses we have discussed in recent years, for example the flu virus, the cold virus and the COVID-19 virus are about 1 tenth of a micron (0.1 micrometers), while HIV, that of AIDS is slightly larger and the fearsome ZIKA less than half.

Why are we interested in this? Because when we breathe in particulate matter - and we do it continuously, willy-nilly - it will more or less penetrate our airways depending on its size. While the larger droplets,> 10micron, will more easily stop on our face or on the mucous membranes of the oral cavity, all the PM 10, therefore also the evaporating part, volatile, of the largest droplets, spreads in all the first ways. aerial, up to the end of the trachea. PM 2.5 will arrive in the bronchi. PM 1, the part of particulate matter <2.5 but not less than one micron, will diffuse into the pulmonary alveoli. While PM 0.1 and below will overcome the barrier between alveoli and blood and spread throughout our body carried by the bloodstream. This is normally done in one direction and in the other by oxygen and carbon dioxide, for example, which are measured in picometers, millionths of microns.

But we are especially interested in the medicines we take: sprays, aerosols, puffs… they will diffuse more or less into our airways. Normally reaching up to the trachea, certainly in their volatile components rather than in the aqueous ones, and with particular dispensers, such as those of the puffs, which deliver particles suitable for reaching our lungs

Remember to always take a deep breath when using aerosol or spray products and to follow the instructions with the puffs, to let the contents distribute themselves with the desired effectiveness

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