The number and size of visible alpha particle tracks in different cellulose derivatives (nitrate, acetate, acetobutyrate, and propionate) and other polymer foils depends mainly on the chemical structure and physical treatment of the foils, the presence or absence of oxygen during irradiation, the humidity and/or chemical pre- or post-treatment of the foils, and on the etching conditions. The stability of unetched tracks decreases close to the softening temperature of the plastics. Up to 100°C the fading in the investigated foils is small. Cellulose derivates are most suitable for several applications, such as (a) simple and inexpensive personnel dosimetry of radon and radon daughters in uranium mines; (b) thermal neutron dosimetry using (n, alpha) reactions in B, Li, etc.; (c) fast neutron measurements via (n, alpha) reactions and recoil reactions in the foil. The sensitivity of this method is superior to the fission fragment registration above ca. 1 MeV, but there is a directional dependence up to −30%. Very high energy neutrons can also be measured via spallation in high-Z cover materials. Some depth-dose measurements for neutrons of different energies are reported.