As nanoparticles are omnipresent in the natural environment, one cannot really protect oneself from them in daily life and dust masks help only partially. Up to 10,000 naturally occurring nanoparticles per cubic centimeter fly around in clean air. The smoke of one cigarette increases the amount of these particles to over 100,000 in the surrounding area. The natural nanoparticles derive from dust storms (e.g. in the Sahara), forest fires, volcanic eruptions, etc., and can be transported over large distances. Normally, this is nothing to worry about, because our body can handle these nanoparticles. Yet, in principle, protection is possible: In the nanoparticle industry, employers must provide appropriate protective equipment (fume hoods, clothing, masks with “nano-filters”) to ensure that employees are not endangered. For best possible protection, the maximum allowable values are reviewed annually.