UV LIGHT APPLICATIONS

APPLICATIONS OF Ultra Violet LIGHT

1] Air Sterilization

UV lights have many applications in industries, households, and healthcare for controlling the odor, environment sterilization and to eliminate harmful volatile organic compounds emitted by factories. In some environments where air quality is crucial for health.

2] Surface Sterilization

In industries like food processing disinfecting the surfaces without the chemical is essential where UV lamps are used. The UV lamp works with the principle of irradiation where ultraviolet light can kill bacteria, viruses, and fungi in a couple of seconds. This will help in extending the shelf life of a food product and preserve the nutritional value. These lights can be installed along with conveyor belts where all incoming foodstuffs get scanned.

3] Water Disinfection

Water disinfection is important to make the water safe for human use by eliminating harmful chemicals like chlorine and environmentally toxic. UV lights are used in the treatment of this water. Other applications like in aquaculture and life science.


4] Arson Investigation

The UV lights are sensitive to the carbon residues from the burning effect on walls, floors, and furniture which helps the fire inspector to scan the fire impacted areas instantly without checking physically.

5] Artwork Inspection

The Ultraviolet lights have a different effect on each material which helps in identifying it. This helps the artwork inspectors to protect themselves from art fraud. It also helps in identifying the repairs in art and other valuable stones like marbles, gems, and even on ivory. It also can detect the age of precious stones.

6] Beauty and Skincare

Ultraviolet light also used in treating skin problems. UV light therapy is usually offered in medical clinics and other licensed professionals. It is used to treat skin problems like Eczema, Vitiligo, Itching, and other problems.

7] Crime Scene Inspection

UV lights are used in forensics to identify the fingerprints, blood, and other body fluids in crime scene investigation. UV lights make these samples glow brightly and it becomes easy to identify.

8] Counterfeit Currency Detection

Ultraviolet light source scanners make different currency denominations glow with a specific color and will show whether bills are genuine or counterfeit.

9] Document Verification

UV light plays an important role in document verification like driver’s licenses, passports, and credit cards. An official document has invisible fluorescent markings that are visible only by using UV light sources.

10] Environmental Investigations

UV lights assist in the environmental investigations by detecting the presence of harmful chemical wastes like hydrocarbons disposed of by petroleum factories. It can be detected on the land and even in water.

11] Gem and Mineral Inspections

Impurities and structural flaws present in the valuable gems stones can be detected by using a UV light. It is used by a gemologist to identify the authentication of gemstones.

12] Non-Destructive testing

UV lamps projected on the surfaces that have been previously treated with a liquid penetration or magnetic particle, which will fluoresce under ultraviolet light, exposing any flaws in the material being examined.

13] Pest Control/ Food and Agriculture

To determine the presence of rodents in the warehouses by scanning urine and hair as it glows blue-white and is easily identified on sacks of food or intermixed with food grains. It also helps in trapping flying insects.

14] Security control

Security professionals need to track visitor’s baggage and items at a public gathering for security concerns. So, these items were more likely inspected with a UV light source which is monitored using screens.

UV Light and How UV radiation Kills Microbes

UV Light: Ultraviolet is an electromagnetic radiation which has a wavelength between 100nm to 400nm. UV radiation is not visible to human eye. Lamps, bulb, crackling fire are some examples of objects that emit UV radiation.

source: http://www.lightlab.com/smarter-uv-light/what-is-uv-light

UV region is divided into three bands

  • Ultra Violet A(315-400nm): UVA possess the lowest energy compared to UVB and UVC. It enters deep into the skin causing various skin damages such as wrinkling of the skin, skin cancer and ageing.
  • Ultra Violet B(280-315nm): UVB has the highest energy compared to UVA and UVC. It affects the outer layer of skin causing sunburn, skin cancer and tans.
  • Ultra Violet C (100-280): Highest energy than UVA and UVB. But it doesn’t reach the earth’s surface, it is absorbed by the ozone layer.
source: http://www.arpansa.gov.au/understanding-radiation/what-is-radiation/non-ionising-radiation/ultaviolet-radiation

According to World Health Organization, as sunlight travels through the atmosphere all UV-C and about 90% of UV-B energy are drawn by ozone, water vapour, oxygen and CO2. UV-A radiation is less affected by the atmosphere compared to other two radiation. Therefore, the UV radiation touching the earth’s surface is mainly composed of UV-A with a small amount UV-B factor.

Ultraviolet germicidal irradiation (UVGI) is a decontamination method that uses shorter wavelength UV radiation to inactivate microbes by terminating nucleic acids and disrupting their DNA which makes them powerless to perform certain vital cellular purposes. UVGI is used in a various applications such as food, air purification and water purification.

Killing the microorganisms with UV radiation needs the germicidal wavelengths of between 185 to 254 nanometers. UVC light on earth’s surface is very weak, since the ozone layer blocks it. UVGI devices produces sufficient UVC radiation in air or water systems which breaks apart the derm DNA to make them inactive in environments to microbes such as bacteriaviruses other pathogens. UVC has the strongest germicidal outcome which is very effective in killing or inactivating bacteria, viruses and other pathogens.

A group of single celled microbes which reproduce through the process of cell division are called Bacteria. This single cell feature of bacteria makes it decontaminated by UV radiation as the major form of reproduction in bacteria happens through the process of cell division. Any form of modification in the cell structure of the bacteria can affect the method of cell division.

HOW UV RADIATION KILLS CELLS

DNA is made up of two complementary strands that are twisted together into a double helix structure. This structure is made up of four nucleotides Adenine(A), Thymine(T), Guanine(G) and Cytosine(C). UV radiation kills the cells or the process of cell division by damaging their DNA. When UV light falls on bacteria it initiates a reaction between two thymine molecules, it is one of the bases that form DNA. The subsequent thymine dimer produced is very stable but fixing this DNA damage is by removing the two thymine bases and replacing with new nucleotides, which is not an efficient method.

[Dimers: It’s a chemical compound made up of two identical subunits or monomers]

Extensive exposure to UV radiation results in the formation of more thymine dimers in the DNA which produces an incorrect repair or missing dimer. If the process of cell division is interrupted due to an incorrect repair, missing dimer or any damage then the cell cannot do its normal functions. At this point the cell will die or directs the cell to apoptosis.

CALCULATION OF EXPOSURE TIME REQUIRED FOR DISINFECTION:

The unit of brightness is typically expressed in microwatt per centimeter (μW/cm2) and the exposure time employed for UV sterilization is directly proportional to UV dosage. The mathematical calculations for the same are as shown below.