South African studies also used the spirometer to address racial and class differences. Eustace H. Cluver conducted vital capacity measurement research at the University of Witwatersrand and found that poor white people had physical unfitness but that it was attributable to environmental issues rather than genetics. Using these studies, Cluver argued to the South African Association for the Advancement of Science during World War Two that improving both nutrition and physical training programs could help produce wealth and win the war by increasing the working capacity of individuals across all races as their labor was necessary to achieve these ends. Racism and the spirometer intersected again in these studies when further research was conducted on the effects of physical training on poor white recruits; vital capacity studies showed that 'the poor-white is biologically sound and can be turned into a valuable citizen' but no comment was made on the outcome of black South Africans.