What is ultraviolet light ?
Ultraviolet (UV) light is a short wavelength light invisible to the human eye. When it comes to wavelengths, lights in our homes and outdoors are a longer wavelength light while X-rays are a shorter wavelength light. UV falls between the two.
The sun puts out three different types of ultraviolet light: UVA light, UVB light and UVC light. The first two are let into the atmosphere in various intensities and are what cause wrinkles, sunburns, etc. UVC light is almost completely absorbed by the earth’s ozone layer, so it’s generally the one that people are less familiar with – but it’s powerful none the less.
What are the different types of UV light ?
Scientists categorize UV light into several different subtypes:
- UV-A light (320-400nm) is UV light with the longest wavelength, and the least harmful. It is more commonly known as “black light”, and many use its ability to cause objects to emit fluorescence (a colored glowing effect) in artistic and celebratory designs. Many insects and birds can perceive this type of UV radiation visually, along with some humans in rare cases such as Aphakia (missing optic lens).
- UV-B light (290-320nm) causes sunburns with prolonged exposure along with increasing the risk of skin cancer and other cellular damage. About 95% of all UV-B light is absorbed by the ozone in Earth’s atmosphere.
- UV-C light (100-290nm) is extremely harmful and is almost completely absorbed by Earth’s atmosphere. It is commonly used as a disinfectant in food, air, and water to kill microorganisms by destroying their cells’ nucleic acids.
How can ultraviolet light kill germs ?
It was discovered in 1877 that UV light kills bacteria and viruses. In 1902 it was narrowed down to UV-C light specifically, and clocked a 99.9% kill rate of all known viruses, bacteria, mold spores and germs. UV-C light sanitizer acts by penetrating the thin wall of a small microscopic organism and destroying its nucleic acids. This disrupts the DNA structure and either kills it or renders it unable to reproduce (sterilized) – and therefore harmless. As a result, the use of UV-C light to sanitize and kill germs can be applied EVERYWHERE.
The Application of UV-C: The technology was put to use in the early 1900s in Europe for water purification and is still used today. In 1930, UV lights were installed in classrooms by Harvard Sanitary Engineers. They recorded a 75% reduction in Measles transfer cases in classrooms with the UV lamps vs. classrooms without. The trouble they had, was containing the harmful UV-C light. Angel Air has solved this dilemma.
Isn’t a Hepa Filter good enough ?
A HEPA (High-Efficiency Particulate Air) filter can be an important part of common air purifier systems promising to improve the air quality in your home or office. But there are a lot of misconceptions about the HEPA standard, whether or not an air purifier or filter truly meets the HEPA standard, and what a HEPA filter can and can’t do.
To understand how HEPA works, think of it as mesh of tangled fibers. The sheet is usually folded into pleats to increase the surface area and filter life. Air flows through the fibers and large enough particles get trapped when they hit the fibers. So it’s a size game which very clearly helps understand what HEPA can filter and what not. HEPA works well and is effective at removing large enough particulate matter like pet dander, pollen, and dust mites.
While HEPA filters remove some particulates from the air, there are many harmful contaminants in the air that aren’t particulate matter.
Volatile Organic Compounds (VOCs) are airborne chemicals that mostly derive from off-gassing of building materials or products in our homes as well as cleaning products aside from other sources like beauty products. The most concerning health effect associated with VOCs is that some are well-known carcinogens. HEPA filters are unable to remove VOC’s as they simply are far smaller in size than what can be trapped.
Much like VOCs, viruses are also too small to be removed. Despite this fact, HEPA based products were marketed for a long time with the claim to protect from viruses. The US Federal Trade Commission (FTC) has now regulated that HEPA filter based products can no longer make that claim.
While bacteria are large enough to be trapped, bacteria are understood to release endotoxins into the air stream when dying on the air filter surface. Studies have demonstrated that endotoxins cause inflammatory and atopic responses in nonasthmatic and asthmatic participants.
Mold spores are large enough to be caught in HEPA filters but stay alive on the filter surface. Other particles that accumulate and fill the filter start acting as nutrients and allow mold spores to potentially grow on and through the filter membrane and eventually release new spores into the air.
It is important to say that frequent replacement of filters is critical since pathogens collected on the filter can include live organisms and eventually pathogens are re-released into the air.
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