There’s one thing that good air purifiers have in common: a HEPA filter. The reason for this is simple. The UV lights in air purifiers aren’t powerful enough to kill all viruses in one pass. On the other hand, HEPA filters are great at capturing viruses. Data shows that those rated HEPA H13 and higher can capture over 99.9% of viruses in a single pass. Is UV light an added layer of protection? Yes. Is it alone responsible for clean air? Absolutely not.