Ultraviolet radiation, hazards

In addition to splashes and shrapnel, eyes are sensitive to ultraviolet (UV) and visible radiation. While normal levels of visible light are not harmful, exposure to either visible or UV lasers presents a significant hazard. Lasers are discussed separately in Section 7.3.3. Ultraviolet radiation hazards are discussed in Section 5.3.7 and special safety glasses and goggles are available to protect your eyes against this radiation. 

We begin our exploration of delocalized bonds with ozone, O3. As described in Chapter 7, ozone in the upper stratosphere protects plants and animals from hazardous ultraviolet radiation. Ozone has 18 valence electrons and a Lewis stmcture that appears in Figure 10-36a. Experimental measurements show that ozone is a bent molecule with a bond angle of 118°. 

Zappi ME, Fleming EC, Thompson DW, et al. 1990. Treatability study of four contaminated areas at the RMA, Commerce City, Colorado using chemical oxidation with ultraviolet radiation catalyzation. Proceedings of the 7th National Conference on Hazardous Waste Materials, 405-409. 

Radiation Hazards. Ultraviolet light from a mercury lamp or carbon arc can be highly damaging to the eyes. Ordinary glasses give some protection, but the experimental arrangement should be well shielded so as to decrease the possibility of accidental exposure to a minimum. Prolonged exposure of the skin to such radiation can produce a severe sunburn. ... 

Hazards. Eyes and skin can be severely injured by ultraviolet radiation. One should avoid looking at the reaction mixture when the irradiation source is activated. The photochemical apparatus, especially when using immersion set-ups, must be wrapped appropriately to avoid exposure to the ultraviolet radiation. In view of the high temperatures produced by the lamp, efficient cooling is mandatory. Special care must be exercised when flammable solvents are used. Ozone is also produced, so that working in an efficient hood is essential. Furthermore, proper electrical safety is necessary to avoid high voltage shocks. 

Ozone absorbs ultraviolet radiation below 320 nm. It thus forms an indispensable shield in the upper atmosphere, protecting the Earth s surface from most of the potentially hazardous effects of such high-energy electromagnetic radiation. There is now increasing concern because atmospheric pollutants are depleting the ozone layer worldwide, with the most serious depletion over Antarctica as a result of seasonal variations in high-altitude air circulation. In the upper atmosphere, ozone is formed from O2 ... 

The environmental hazard posed by this series of reactions is that the level of ultraviolet radiation reaching the earth would be expected to increase as more and more ozone molecules are destroyed. Ultraviolet radiation has been implicated in a number of biological problems for plants, animals, and humans, including an increase in skin cancer and in eye problems. In response to this threat, most of the world s nations have agreed to reduce the amount of Freons, CFCs, and other ozone-depleting chemicals produced and sold each year. 

A.M. Bullock (1988). Solar ultraviolet radiation a potential environmental hazard in the cultivation of farmed finfish. In J.F. Muir, R.J. Roberts (Eds), Recent Advances in Aquaculture (Vol. 3, pp. 139-224). Croom Helm, London. 

A. Ultraviolet (UV) Radiation (180 - 400 nanometer (nm), UV-A, B, C). The primary hazards from this wavelength range are damage to either the lens or the cornea of the eye. Long term low level and short term high level exposures can cause corneal and lens opacities (cataracts) or inflammation of the eye. UV radiation can also cause photokeratitis, which is sunburn of the cornea. The threshold for ultraviolet radiation skin burns is similar to that of the cornea. 

Light and/or radiation hazards like optical radiation and poor vision. Sources include welding, cutting, torch brazing, torch soldering, lasers, ultraviolet infrared rays, and glare. 

The development of chemistry has depended strongly upon careful measurements. Historically, measurements of the quantities of substances reacting and produced in chemical reactions have allowed the explanation of the fundamental nature of chemistry. Exact measurements continue to be of the utmost importance in chemistry, and are facilitated by increasingly more sophisticated instrumentation. For example, atmospheric chemists can determine a small degree of stratospheric ozone depletion by measuring minute amounts of ultraviolet radiation absorbed by ozone with satellite-mounted instruments. Determinations of a part per trillion or less of a toxic substance in water may serve to trace the source of a hazardous pollutant. This section discusses the basic measurements commonly made in chemistry and environmental chemistry. 

Eye Hazards Substances that injure the eye or otherwise reduce visual capacity. Examples include organic solvents, alkalis, acids, infrared and ultraviolet radiation, physical hazards, and others. 

Physicians and patients can contribute by means of reducing the quantity of unused medicines, and return them to a pharmacy. The Swedish classification scheme has also been used to bring enviromnental risk and hazard into the decision of the choice of medicine used [27]. For information regarding novel waste water treatment techniques suitable for removal of pharmaceutical substances, e.g. activated carbon, ozonation, and ultraviolet radiation, the reader is referred to the references [28-32],... 

Infra-red radiation is generated by fires and hot substances and can cause eye and skin damage similar to that produced by ultraviolet radiation. It is a particular problem to fire fighters and those who work in foundries or near furnaces. Eye and skin protection are essential. Microwaves are used extensively in cookers and mobile telephones and there are ongoing concerns about associated health hazards (and several inquiries are currently underway). The severity of any hazard is proportional to the power of the microwaves. The principal hazard is the heating of body cells, particularly those with little or no blood supply to dissipate the heat. This means that tissues such as the eye lens are most at risk from injury. However, it must be stressed that any risks are higher for items, such as cookers, than for low-powered devices, such as mobile phones. 

Ions are produced in air by high temperatures or ultraviolet radiation. The ionized air can be sufficiently conductive to reduce static hazards. The static charge is conveyed by tiie ionized air firom an object to a groimding electrode located nearby. When UV lamps are used, eye protection is required. 

---