Optical nanofibers are highly attractive tools that are used in an increasing number of applications. However, at these radii typically smaller than the wavelength, the optical field is highly sensitive to dusts that rapidly degrade the optical transmittance, which is an issue for their use and storage. In this work we propose and characterize simple and efficient solutions. The chosen nanofiber radius is 500 nm. Firstly, we make systematic and long-term measurements (over several months) of nanofiber optical transmittance at 1.5 μm in two protected environments that can be easily found in almost any laboratory and differing by their levels of cleanliness. We show that the rate of decrease of the optical transmittance is very low when the nanofiber is put in a simple protection box and ten times lower when the nanofiber is put in an airtight box. Secondly, the repetition of these measurements gives a mean value of this rate of −5.2 × 10 −2 %/day in the protection box and −6.3 × 10 −3 %/day in the airtight box. Thirdly, we perform the optical transmittance measurements on two nanofiber lengths (2 cm and 7 cm) and show that there is no significant difference on the rate of degradation between the two lengths. These results also enable to predict the value of the optical transmittances after several months or even years, which is a key parameter for most of the applications using nanofibers.