Germicidal disinfection is a relatively new technique for inactivating bacteria, microbes, and fungi. Since its inception, scientists have made many new discoveries to improve its efficiency — resulting in cleaner, healthier drinking water, swimming pools, indoor air, and surfaces. We are thankful for those who have paved the way for the emergence of germicidal ultraviolet technology.
Water Purification in Ancient Times
Since before recorded history, man has relied on water for drinking, bathing, and recreation. Swimming pools have been around since 2600 BC. It didn’t take long to discover that these bodies of water lose their clarity rather quickly, especially when inhabited by people for any duration of time. The writings of many ancient cultures show evidence of attempts at water purification, primarily for drinking purposes, such as boiling, sunlight, copper, and charcoal filtration. But the ability to disinfect water on a larger scale would not come into play until the modern era.
The Discovery of Microorganisms
In the mid-1600s, scientists began to discover precisely why water becomes tainted. Using primitive microscopes, microorganisms were observed infesting water after people used it. Water from natural sources like lakes and riversopen_in_new was also found to commonly contain parasites. Around this same time, scientist Isaac Newton and his contemporaries were just starting to gain an understanding of the bands of light in the visible spectrum.
The Groundwork for Germicidal Disinfection
A little over 100 years later, German chemist Johann Ritter was investigating energy beyond the visible light spectrum. He already knew that photographic paper turned black more quickly in blue light than in red light. When deciding to expose paper to light beyond violet, which is at the short end of the spectrum, he discovered ultraviolet lightopen_in_new (literally, “beyond” violet).
Following Ritter’s lead throughout the 1800s, scientists showed great interestopen_in_new in the effects of sunlight. But it wasn’t until 1877 when Arthur Downes and Thomas Blunt observed and reported that rays of light from the sun clearly hindered the growth of bacteria. Around the turn of the century, scientists began to narrow down the range of light, measured in nanometers, which could be termed “biocidal.” Improvements in artificially producing these wavelengths using arc lamps also occurred at this time.
The Germicidal Disinfection Wavelength
More experimentation brought more advances in the application of artificial UV light. In the late 1920s, scientist Frederick Gates observed that wavelengths in the 265 nm range were particularly effective against Staphylococcus aureus and Bacillus coli. In 1932, Ehrismann and Noethling isolated the most effective wavelengthopen_in_new for neutralization of microorganisms as 253.7 nm. It was discovered years later that this wavelength matches that of nucleic acid absorption, pointing to DNA damage as the cause for bacterial inactivation via germicidal ultraviolet light. Shortly thereafter, in 1936, Westinghouse Corporation in conjunction with Duke University doctor Deryl Hart first designed commercial ultraviolet lamps for use in operating roomsopen_in_new. Using these fixtures resulted in a sharp decline in surgical infections and quicker wound healing.
Germicidal Disinfection in the Modern Era
Further research and study continued into the 1960s, laying the groundwork for our modern understanding and implementation of UVGI technology, not only as a water disinfection tool, but in air and on surfaces as well. Microbial pathogens such as bacteria, viruses, spores, fungi, and mold are rendered inactive by the power of UV. Germicidal ultraviolet light, emitted at the wavelength of 254 nanometers for a certain amount of time (depending on the lamp’s intensity), will attack and damage links in a microorganism’s DNA chain. It will be unable to replicate, and be rendered harmless. Each pathogen needs a different dose of UV-C to be neutralized, like the examples seen here, measured in millijoules per centimeter squared.
Learn More, Shop & Contact Our Specialists
Since 1963, we’ve engineered and manufactured germicidal ultraviolet equipment to combat all kinds of harmful microorganisms in water, in air, and on surfaces. We help people live healthier — in homes, healthcare facilities, workplace environments, and many more applications. Visit these helpful pages:
Shop at AtlanticUltraviolet.com
- Shop UV-C Water & Liquid Disinfectionopen_in_new
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