Originally designed for industrial use; N95 masks became a healthcare standard subsequent to virus-blocking technology invented by University of Tennessee professor Peter Tsai,[41][42] and patented in 1995.[43] The anti-viral technology was first developed to prevent the spread of drug-resistant tuberculosis.[4][5] Following the onset of the COVID-19 pandemic, Tsai ended his retirement to help alleviate shortages related to the 2019–20 coronavirus pandemic, by researching N95 mask decontamination.[41]