The scientific community has known for well over 100 years that one of the most effective sterilizers is natural sunlight, specifically the invisible ultraviolet C-band (UV-C) part of the spectrum (peaking at 253.7nm). The search for understanding of UV light began in 1877 when scientists discovered that bacteria laden water could become disinfected when exposed to direct sunlight.
UV-C rays from the sun act as a natural sterilization system, inhibiting the growth and reproduction of biological pollutants. Unfortunately, this natural sterilization process can not occur indoors because UV-C light cannot pass through glass, plastics or other inorganic materials.
According to the Environmental Protection Agency (EPA), indoor air is at least five times (and up to 100 times) more polluted than air outside that is exposed to the sun. These pollutants cause the immune system to overreact producing inflamed mucous membranes, allergic reactions, upper respiratory distress, asthmatic outbreaks, and chronic headaches. Biological agents can also greatly increase susecptibility and the severity of colds, flu, viral and bacteria infections, some aggressive enough to result in severe illness. (1,2)
UV-C light sterilizes biological pollutants including viruses, bacteria, mold, and dust mites by penetrating their cell membranes, destroying their DNA, and dismantling their reproductive capabilities. The result is the effective elimination of allergy and disease-causing microbes living and multiplying on the floors and surfaces inside your home. Light disinfection has been used in hospitals, food processing facilities, water treatment, and HVAC systems for over 30 years. The technology is proven and recognized by the Environmental Protection Agency (EPA), Food and Drug Administration (FDA) and United States Department of Agriculture (USDA) as a valid and effective means of eliminating biological contaminants.
UV-C’s natural disinfectant properties have the added benefit of being chemical-free, odorless, and without side effects. Each year, according to the EPA, the average American uses approximately 25 gallons of toxic and hazardous chemical products at home, much of which is eventually returned to the environment. These products greatly affect the health of the people, plants, and animals, as well as the land and water in and around our neighborhoods. Of the approximately 17,000 chemicals found in household cleaning products, only about 30% have been tested for their effect on humans and the environment. (1)
The Children’s Health Environmental Coalition reported that many household cleaning product labels omit inactive or inert ingredients that can make up as much as 90 percent of a product’s volume. These include solvents, dispersal agents, dyes, and fragrances, which contribute to indoor pollution and respiratory issues.
Many of the cleaners’ active ingredients are suspected carcinogens or known contributors to long-term health problems such as allergies, asthma, and even neurological disorders. As an example, diethyl phthalate, commonly found in commercial cleaning products, is a known endocrine disrupting chemical (which can interfere with normal growth and development). Toluene, a chemical found in some stain removers, has been classified by the EPA as a carcinogen — and studies have linked it to neurological problems and birth defects. (1)
UV-C, used as directed in a thoughtfully developed delivery system, is both a safe and environmentally correct method for household disinfection and the prevention of illness and disease. Direct UV-C exposure to skin and eyes should be avoided. However, human contact only becomes dangerous when done at extremely close range or high output levels.
Dental Hygienists work with UV light to help whiten their patient’s teeth. The American Conference of Governmental Industrial Hygienists (ACGIH) provides the following guideline for exposure to UV light (315 to 400nm): A radiant exposure to the eye should not exceed 1.0 J/cm2 for periods greater than 1,000 seconds (approximately 16 minutes). For exposure times less than 1,000 seconds, the dose (total energy) should not exceed 1.0 J/cm2
It is important to remember that UV-C light is invisible and must be shone directly or upon a reflective surface to be absorbed by a biological organism. The blue hue from the light is provided as a reference for the user but is not the UV-C light itself. Indirectly contacting or viewing the blue light produced by the UV-C lamp does not provide the user exposure to UV-C.
UV-C light destroys the DNA of biological pollutants and other pathogens and eliminates their ability to multiply. Specifically, UV-C light damages the nucleic acid of micro- organisms by forming bonds between certain adjacent base pairs in the DNA. The formation of these bonds prevents the DNA from being “unzipped” for replication and the organism is then unable to reproduce. When the cellular organism attempts to replicate under these conditions, it dies in the process. In the case of single-celled organisms, the result is almost immediate. With more complex organisms like dust mites, the process is more involved but equally effective.
The energy required to kill micro-organisms is a product of the UV light’s intensity and exposure time. The energy is measured in micro-watt seconds per square centimeter (expressed as mW/cm2 or joules/cm2).
Intensity X Exposure Time = micro-watt seconds/ cm2. The chart below illustrates the UV-C output of Verilux CleanWave® products relative to the exposure rate required to kill common bacteria, viruses, yeasts, and molds. UV-C can achieve a 99.9% kill rate, however, the most effective use is to achieve a 90% rate and return for additional treatments. A surface treated twice at a rate of 90% effectiveness has a net result of a 99% kill rate.
Example: 100 bacteria per square centimeter exposed to UV-C for a 90% kill rate means 10 bacteria remain. When a second application is applied the remaining 10 bacteria are exposed to a 90% kill rate and 1 bacteria remains. The net effect over 2 exposures is to reduce the bacteria count from 100 to 1 or a 99% kill.
This example is theoretical because it assumes no new bacteria is formed. However, the cumulative effect of ongoing use quickly over takes the replication process, often resulting in a sustained kill rate of greater than 90%.