This paper aims at investigating the influence of environmental agents (sun light, oxygen, ozone, humidity, air pollutants, etc.), particularly those in towns (industrial region) and those in villages, on the fibre degradation process. Another question rises how high degree of reality is present in results obtained for ageing investigation in artificial environment, using Xenotest apparatus (absence of pollutants). The results obtained from these three experiments are compared. Investigations were done on uncoloured PP fibre, of high isotactic index (around 98%) and 14,5% dtex fineness. As the fibre is a commercial one, it contains an UV-stabiliser (0,1% Irganox + 0,1% PS). On the fibres treated in different environment of condition, and in different periods of time (2 months to 12 months in natural environment, and 50 hours to 1000 hours in Xenotest), the following characteristics have been determined: isotactic index, breaking load, resistance to torsion-load and fibre surface changes.

Tekstilna tehnologija