Since the popularisation of air ionisers in the late twentieth century, scientists have been conducting experiments and studies to figure out the potential medical benefits of air ionisation devices. In the twenty-first century, they have found these devices to be medically advantageous in a number of obvious and not-so-obvious ways.
Mitigates Pollen-Induced Allergies
According to Dr. William C. Shiel at medicinenet.com, tiny particles from trees and plants and flowers, known as pollen, often enter human noses and throats instead of reaching their intended destination, triggering a type of seasonal allergic rhinitis called pollen allergy, which many people know as hay fever. Air ionisers use electricity to charge air particles and draw them into the device, thereby clearing the air of pollen and other contaminates. With less or no pollen in the air, allergy sufferers can breathe easier and not suffer the itchy eyes and runny nose that often comes with pollen-induced allergies.
Reduces the Spread of Infections
In addition to removing pollen from the air, ionisers have also been used to remove infectious bacteria from hospital rooms. According to Natasha McDowell in a 2003 New Scientist article, the University of Leeds conducted a year-long epidemiological study and found that the continual use of negative air ionisers in the intensive care ward of St. James Hospital completely wiped out the bacteria acinetobacter from the air. McDowell writes that "the scientists believe charged particles aggregate together and fall out of the air, thereby disinfecting the atmosphere and stopping the transmission of infection." Brian Duerden, director of the UK's Public Health Laboratory Service, added that the air ioniser "is a potential addition to the weaponry against hospital infections."
Helps Fight Seasonal Depression
In a 2007 article published in the Psychiatric News, Joan Arehart-Treichel describes a study in which Michael Terman, Ph.D., director of the Center for Light Treatment and Biological Rhythms at Columbia University Medical Center, found that negative air ionisation can counter the symptoms of seasonal affective disorder. In the study, the subjects exposed to negative air ionisers had comparable improvements to subjects exposed to bright light. However, the subjects exposed to the ionisers were able to sleep without interruption, which offered an advantage over those subjects whose sleep was interrupted with bright light.