The ISWP Standards Working Group recognizes that wheelchairs suffer from mechanical stresses and effects from environmental factors. Environmental factors include different ground surfaces, temperature, humidity, and dirt. Impacts and shocks can cause parts to break and low-cycle loading can cause metal fatigue. High temperature and greater exposure to ultraviolet light causes wheelchair parts to wear and degrade. Humidity and exposure to water and sand can cause corrosion of metal parts. Dirt and dust may lead to contamination of rolling elements like bearings. None of the ISO tests subject the wheelchair to combined effect of these test factors and hence, testing the complete chair against a combination of aforementioned test factors is suggested. The whole chair test method incorporates permutations and combinations of several quality-degrading factors to replicate failures as seen in the field.