When I was growing up (many years ago), the medical profession emphasized the importance of fresh air and sunshine. Hospitals had open windows, and many had sunrooms.

Today, windows have been completely removed from intensive care units, and no windows are left open anywhere else in the hospital. The only air patients are allowed to breathe is pumped in through filters.

As a medical student, I worked at Charity Hospital in New Orleans — also called Big Charity. As a 2,680- bed facility, it was the second largest charity hospital in the United States. Working on the upper floors of Big Charity in the summer months was an ordeal because the heat and humidity were stifling. To try to relieve the heat, all the windows were left open, as were doorways leading to the wards.

We now know that the survival of pathogens (germs) is dependent of several factors, including temperature, humidity, ultraviolet (UV) light exposure, ventilation, and movement of people.

Despite what you are being told today, medical science still has not determined just how infections are transmitted. However, four mechanisms are suspected:

• Contact: touching contaminated objects

• Dust: contaminated particles that flow through the air

• Respiratory droplets: released mainly during coughing or sneezing

• Droplet nuclei: what are now called aerosols, which dry quickly

A number of studies have found that droplets and aerosols released by talking, coughing, sneezing, or laughing actually contain far fewer live viruses than previously suspected.

In fact, one study found no live viruses being transmitted by any of these activities — meaning face masks are virtually useless for preventing the spread of viral infections.