A Lesson From the Spanish Flu: Sunshine and Fresh Air are Our Best Friends Right Now

Patients in “open-air” hospitals were 3 times as likely to survive the 1918 Spanish flu as those treated indoors.

Influenza patients getting sunlight at the Camp Brooks emergency open-air hospital in Boston. Medical staff were not supposed to remove their masks. (National Archives)

Records from the H1N1 “Spanish flu” pandemic of 1918-1919 suggest sunshine and fresh air were among the most helpful therapies in stopping the spread of the illness and reducing mortality rates of those who had it.

“Put simply, medics found that severely ill flu patients nursed outdoors recovered better than those treated indoors,” writes Dr. Richard Hobday, an infection control and public health researcher.

The Spanish flu is the most devastating pandemic on record, killing between 50 million and 100 million people, around a quarter of the U.S. population at the time.

“The conventional view is that little could have been done to prevent the H1N1 virus from spreading or to treat those infected; however, there is evidence to the contrary,” Hobday writes in a research paper published in the American Journal of Public Health.

Records from an “open-air” hospital in Boston, Massachusetts, suggest that some patients and staff were spared the worst of the outbreak.

The combination of fresh air and sunlight seems to have prevented deaths among patients; and infections among medical staff,” he writes.

The city of Boston was hit particularly hard by the Spanish flu. The State Guard set up an emergency hospital for the worst cases among sailors arriving in the Boston harbor.

The hospital’s medical officer noticed the sickest sailors were in poorly-ventilated spaces. So he put them in outdoor tents for fresh air. In good weather they were rolled out into the sun, Hobday says.

According to one report, published in the American Journal of Public Health, the regimen reduced deaths among hospital patients from 40% to 13%.

That means patients who were treated outdoors were three times more likely to survive, compared to indoor patients.

Fresh air

At that time, open-air therapy was also widely used on WWI casualties and tuberculosis patients.

Patients were either rolled outside in their beds or nursed in cross-ventilated wards with the windows open day and night.

Open-air therapy remained popular until antibiotics replaced it in the 1950s.

In the 1960s, tests by Ministry of Defense scientists proved that fresh air is a natural disinfectant.

“Something in it, which they called the Open Air Factor, is far more harmful to airborne viruses and bacteria than indoor air,” Hobday said.

No one could identify exactly what it was about fresh air that caused germs to die, but they found it was effective both during the day and at night.

The discovery of the Open Air Factor led to the building of cross-ventilated hospital wards, with high ceilings and big windows, a design long-forgotten in modern hospital buildings.


During the First World War, military surgeons routinely used sunlight to heal infected wounds, Hobday notes.

They knew it was a disinfectant, but didn’t know why.

The link between low vitamin D and respiratory infections was not made until the 1920s.

More recent studies have since proven the sun inactivates the influenza virus and kills bacteria that cause lung and other infections in hospitals.

Also, our body’s biological rhythms influence how we resist infections. A new study suggests they can alter our inflammatory response to the flu virus. Sunlight plays an important role in synchronizing these rhythms.

“If the Covid-19 crisis gets worse, history suggests it might be prudent to have tents and pre-fabricated, open-air hospitals ready to deal with large numbers of seriously ill cases,” Hobday says.