UV light cuts spread of TB

Ultraviolet lights could reduce the spread of tuberculosis in hospital wards and waiting rooms by 70 per cent, according to a new study involving researchers from the University of Leeds. The study explores the transmission of tuberculosis (TB) from infected patients, and suggests that installing simple ultraviolet C (UVC) lights in hospitals could help reduce the transmission of even drug-resistant strains.

Every year, more than nine million people are infected with tuberculosis and approximately two million people die from the disease, according to the World Health Organisation. Infection rates are particularly high in places where vulnerable people are crowded together, such as hospitals, homeless shelters and prisons.

When a tuberculosis patient coughs, bacteria are sprayed into the air in tiny droplets, floating around the room and infecting other patients, visitors and healthcare staff. These bacteria can be killed by hanging a shielded UVC light from the ceiling and ensuring an effective system to move and mix the air, say the researcher team, which includes the University of Leeds, Imperial College London, Hospital Nacional Dos de Mayo, Lima, Peru, and other international institutions.

UVC light kills tuberculosis bacteria, including drug-resistant strains, by damaging their DNA so they cannot infect people, grow or divide. It is already used at high intensity to disinfect empty ambulances and operating theatres.

The impact of UV lights is greatest when combined with careful management of the air flow on the wards, as Dr Cath Noakes from Leeds’ Faculty of Engineering explains: "The lights must be set high enough to ensure patients and health workers are not overexposed, but if the lights only treat air at that level, there will be little benefit. To be most effective, ventilation systems need to create a constant flow of treated air down to patient level, and potentially infected air up towards the lights."