Infrared heat may be a hot new trend in grilling, but this type of heat has been occurring naturally since the dawn of time. In fact, everything with a temperature above absolute zero (which is equal to -459.67 degrees Fahrenheit or -273.15 degrees Celsius) emits at least a little infrared radiation.
For example, bacterial and viral causes of pinkeye are almost always contagious and are spread from person to person. However, pinkeye caused by allergens and chemical irritants is not contagious by person-to-person contact. Pinkeye that is contagious has an incubation period as long as 14 days. However, most doctors do not think that pinkeye becomes contagious to other people until symptoms start to develop.
Viral and bacterial conjunctivitis are the most common types of pink eye. The viral form is caused by the same virus as the common cold, and usually improves on its own over the course of seven to ten days. For the first ten days (or as long as there are symptoms), viral conjunctivitis is very contagious.