copper alloys c11000 (99.9% copper), c51000 (95% copper), c70600 (90% copper), c26000 (70% copper), and c75200 (65% copper). stainless steel (s30400) was used as the experimental control. the copper alloys significantly reduced the viability of both c. difficile spores and vegetative cells. on c75200, near total kill was observed after one hour (however, at six hours total c. difficile increased, and decreased slower afterward). on c11000 and c51000, near total kill was observed after three hours, then total kill in 24 hours on c11000 and 48 hours on c51000. on c70600, near total kill was observed after five hours. on c26000, near total kill was achieved after 48 hours. on stainless steel, no reductions in viable organisms were observed after 72 hours (three days) of exposure and no significant reduction was observed within 168 hours (one week). influenza a main article: influenza a virus influenza, commonly known as flu, is an infectious disease from a viral pathogen different from the one that produces the common cold. symptoms of influenza, which are much more severe than the common cold, include fever, sore throat, muscle pains, severe headache, coughing, weakness, and general discomfort. influenza can cause pneumonia, which can be fatal, particularly in young children and the elderly. after incubation for one hour on copper, active influenza a virus particles were reduced by 75%. after six hours, the particles were reduced on copper by 99.999%. influenza a virus was found to survive in large numbers on stainless steel. once surfaces are contaminated with virus particles, fingers can transfer particles to up to seven other clean surfaces. because of copper's ability to destroy influenza a virus particles, copper can help to prevent cross-contamination of this viral pathogen. adenovirus main article: adenoviridae adenovirus is a group of viruses that infect the tissue lining membranes of the respiratory and urinary tracts, eyes, and intestines. adenoviruses account for about 10% of acute respiratory infections in children. these viruses are a frequent cause of diarrhea. in a recent study, 75% of adenovirus particles were inactivated on copper (c11000) within one hour. within six hours, 99.999% of the adenovirus particles were inactivated. within six hours, 50% of the infectious adenovirus particles survived on stainless steel. fungi the antifungal efficacy of copper was compared to aluminium on the following organisms that can cause human infections: aspergillus spp., fusarium spp., penicillium chrysogenum, aspergillus niger and candida albicans. an increased die-off of fungal spores was found on copper surfaces compared with aluminium. aspergillus niger growth occurred on the aluminium coupons growth was inhibited on and around copper coupons.