**To serve/reach our customer better, S&A Impex has started its operation by opening its branch office at Tirupur and Ludhiana and by this year end other branch office will be there in Bangalore, Kolkata and Mumbai.

This advertisment & article on Ultravoilet Radiation, Effects, Prevention is published in COLORAGE August 2007 Issue:

Ultraviolet Radiation, Effects and Prevention

The Background

The name means "beyond violet" (from Latin ultra, "beyond"), violet being the color of the shortest wavelengths of visible light. The color violet has the shortest wavelength in the visible spectrum. UV light has a shorter wavelength than that of violet light.

Ultraviolet (UV) radiation is electromagnetic radiation of a wavelength shorter than that of visible region, but longer than that of soft X. rays. It can be subdivided into near UV (380-200 nm) and extreme or vacuum (200-10nm).

In 1801 the German physicist Johann Wilhelm Ritter made the hallmark observation that invisible rays just beyond the violet end of the visible spectrum were especially effective at darkening silver chloride-soaked paper. He called them "deoxidizing rays" to emphasize their chemical reactivity and to distinguish them from "heat rays" at the other end of the visible spectrum.

When considering the effect of UV radiation on human health and the environment, the range of UV wavelength can be divided into

The limits of the spectral range of ultraviolet radiation are not well defined and may vary according to the user.

Committee E-2.12 of the international Commission on Illumination (CIE) distinguishes in the spectral range between 400 and 100nm.

• UV - A: 315-400 nm
• UV - B: 280-315 nm
• UV - R: 280-400 nm

Earlier referred to as ACTINIC Radiation, the word ultraviolet refers to beyond violet and violet being the color of shortest wavelength of visible light; UV radiation is not visible to the human eye.

The sun emits the full range of UV radiation but most of it gets absorbed in the atmosphere and some of it is responsible of generation of ozone in our atmosphere.

Our concern: The health and other effects

In humans prolonged exposure to solar UV radiation can result in acute and chronic health effects on skin, eye and immune system.

A positive effect of UVB exposure is that it induces the production of vitamin D in the skin. Eating fortified foods or taking a dietary supplement pill is usually preferred to UVB exposure, due to the increased risk of skin cancer from UV radiation.

Quoting WHO document on UV radiation effects:

"Prolonged UV exposure may result in acute and chronic health effects on skin eye and immune system. Sunburn (Erythema) is the best-known acute effect of excessive exposure. Over longer term UV induces degenerative changes in skin cells fibrous tissues, and blood vessels leading to premature ageing of skin, Photodermatoses and actinic Keratoses. Another effect is an inflammatory reaction of eyes. In most serious cases, skin cancer and cataracts can occur. Further more UV radiation may suppress cell-mediated immunity and thereby enhance the risk of infectious diseases and limit the efficacy of vaccination.

It is a popular misconception that only fair skinned people need to be concerned about UV exposure. Darker skinned people can get skin cancer and they are often detected at later and more dangerous stages the risk of UV radiation related health effects on eyes and immune systems independent of skin type."

UVA can contribute to skin damage and ageing of skin, DNA damage and skin cancer. UVA light having longest wavelength can penetrate most windows and is the prime cause of wrinkles of skin.

UVB in particular has been linked to skin cancer such as Melanoma. The radiation excites the DNA in skin cells causing mutations leading to cancerous growth. This cancer connection is one of the reasons for concern about ozone depletion and ozone hole.

UVC are high-energy most dangerous type of UV radiation. These rays are used in sterilization equipment.

Degradation of polymers, pigments and dyes

Many polymers used in consumer products are degraded by UV light, and need addition of UV stabilisers to inhibit attack. Products include thermoplastics, such as polypropylene and polyethylene as well as specialty fibers like aramids. UV absorption leads to chain degradation and loss of strength. In addition, many pigments and dyes absorb UV and change color, so paintings and textiles may need extra protection both from sunlight and fluorescent lamps.

Apart from solar radiation Tungsten-Halogen lamps not filtered by a layer of ordinary glass are dangerous sources of UV radiation. Radiations from sterilization equipment are another source of UV radiation

Uses of UV Radiation

UV lights have got various beneficial uses in the fields of Fluorescent lamps, Pest control, Spectrophotometry, analyzing minerals, Photolithography, checking electrical insulation, Sterilization, Disinfecting drinking water, Food processing, Fire detection, Curing of adhesives and coatings. But keeping in view the health hazards we should take protective measures from the exposure from these radiations.

Protection:

Suntan lotions for face, protective sunglasses with special lenses for eyes can give adequate protection from UV exposure, but the rest of the body and the major part exposed to the radiation is left unprotected as the normal clothes that we wear do not give protection from the harmful UV radiation as these clothes don't prevent the rays to reach our skin.

Innovation:

In order to protect our body from over exposure to the harmful UV radiation the latest technology of treating our clothes with special chemicals helps block the rays from reaching our skin and prevents damage.

The garments treated with these chemicals cut the radiation up to 99.9 % and thereby protect our body from damage.

Apart from this prime benefit these textile-finishing agents enhance the color fastness to light especially the textiles dyed with reactive and direct dyes. These chemicals are durable to wash and give an effect of antipollution to the treated garment.

Testing of the protection Factor:

The efficacy of a chemical treatment and the resultant ultraviolet blocking of the fabric is determined by the Ultraviolet Protection Factor (UPF) by a test method specified in UVR TRANSMISSION AATCC 183: 2004 Transmittance or Blocking of Erythermally Weighted Ultraviolet Radiation through Fabrics

Ultraviolet Protection Factor (UPF) is the ratio of the average effective ultraviolet radiation (UV -R) Irradiance transmitted and calculated through air to the average effective UV- R irradiance transmitted and calculated through fabric.

The UV protection category is determined the UPF values.

• UPF > 40 : Excellent UV protection
• UPF = 25 - 39: Very good UV protection
• UPF = 15 - 24 Good UV protection
• UPF < 15 Unclassified.
  
  Refer to ASTM D6603,

S&A Impex offers a range of products in UV absorber category and also offers technical support for developing this finish at textile and garment stage.

At S&A have tested our range of products at SGS Hong Kong and got the following results:

**These tests have been conducted on Polyester fabric at a particular dosage of chemical. The results might vary with different substrates and dosage of chemicals used.

Contact marketing@snaimpex.com for any further info about UV cut products and applications.

Anil.K.Bhat

Manager- Marketing
anil@snaimpex.com