WHEN scientists first discovered chemical antibiotics in the mid-20th century, doctors hoped that these new medications would eliminate certain diseases. At first, the new medicines seemed to live up to their promise. Yet, their widespread use since then has resulted in the development of antibiotic-resistant bacteria.

To find new weapons against infection, some scientists are taking a second look at disease-control methods of the past. One of these involves harnessing the health benefits of sunshine and fresh air.

England had several early advocates of the curative value of sun and fresh air. Physician John Lettsom (1744-1815) prescribed sea air and sunshine for children who were suffering from tuberculosis (TB). In 1840, surgeon George Bodington noted that those who worked in the open air—farmers, plowmen, shepherds—were generally free of TB, while those who spent much of their time indoors seemed more susceptible to it.

Florence Nightingale (1820-1910) became famous for her innovations in nursing while caring for British soldiers injured during the Crimean War. She asked: “Do you ever go into the bed-rooms of any persons . . . at night, or before the windows are opened in the morning, and ever find the air anything but unwholesomely close and foul?” She recommended that the air in a patient’s room be kept as fresh as the outside air, but without chilling the patient. She added: “It is the unqualified result of all my experience with the sick, that second only to their need of fresh air is their need of light . . . And that it is not only light but direct sun-light they want.” Many at that time also believed that exposing bed linens and clothing to the sun promoted health.

 Science has progressed since the 1800’s, yet modern studies have reached similar conclusions. For instance, a 2011 study in China found that crowded college dormitories with a low rate of ventilation are “associated with more respiratory infections.”

The World Health Organization (WHO) recognizes that natural ventilation, which includes outside air flowing through a building, is important for infection control. Indeed, WHO guidelines published in 2009 encourage use of such natural ventilation as an effective measure in reducing the risk of infection at health-care facilities. *

‘That is all very good,’ you might say. ‘But what is the science behind this? How do sunshine and air prevent infection?’

Studies conducted at a United Kingdom Ministry of Defence site provide some answers. Scientists there were trying to establish how long the air would remain dangerous if a biological weapon armed with harmful bacteria were exploded over London. To determine the viability of airborne pathogens, the researchers anchored E. coli microorganisms to threads of spider silk and exposed them to the open air. The experiment was performed at night, since it was known that sunlight kills these bacteria. What were the results?

Some two hours later, nearly all the bacteria were dead. Yet, when the bacteria were kept in a closed box in the same location and at the same temperature and humidity, most of them were still alive past the two-hour mark. Why? Evidently, something about being in the open air kills germs. This so-called open-air factor has not been clearly identified. However, researchers point to a compound that occurs naturally in open air and that “acts as a natural disinfectant against pathogens or germs that lurk in the atmosphere.”

Sunlight also has natural disinfecting properties. The Journal of Hospital Infection explains that “the majority of microbes that cause airborne infections cannot tolerate sunlight.”

How can you take advantage of this? You might want to go outdoors, where you can spend a moderate amount of time in the sunshine and breathe some fresh air. It will likely do you good.