Asked by: Chaudhary Nikul, India
Viruses can live for a surprisingly long time outside of a body, depending on conditions such as moisture and temperature. They tend to live longer on water-resistant surfaces, such as stainless steel and plastics.
A cold virus can sometimes survive on indoor surfaces for several days, although its ability to cause infection drops dramatically over time.
Flu viruses can survive in the air for several hours, especially at lower temperatures, and on hard surfaces they can survive and remain infectious for 24 hours.
Enteric viruses, such as norovirus (pictured) and hepatitis A, can survive for weeks on a surface if conditions are suitable. The norovirus is known for causing sickness outbreaks in schools, cruise ships and hospitals.
Dr Emma Davies is a science writer and editor with a PhD in food chemistry from the University of Leeds. She writes about all aspects of chemistry, from food and the environment to toxicology and regulatory science.