STATIC VOLTAGE AND ENVIRONMENTAL ION DEPLETION

All VDTs and televisions exhibit an intrinsic problem of producing electrostatic charges on the face of the CRT (cathode ray tube). The charges can reach 50,000 volts per square inch. This positively charged surface tends to attract all negative ions in the intervening air space and neutralize them, thus creating a hazardous ion depletion in the work area of the operator. Numerous health authorities believe that the subsequent ion imbalance results in Video Operator's Distress Syndrome (VODS) which include symptoms such as headaches, fatigue, dizziness, respiratory distress, skin rashes, etc. Also the ion imbalance increases the deposit of dust and other airborne contaminants onto the VDT screen as well as its operator.

Atmospheric ions are electrically charged molecules which make up the constituent gas in the air we breathe. While some controversy exists regarding the specific nature of various species of ions, it is generally agreed that negative ions are charged forms of oxygen and water in the form of O2-(H2O)n and CO2-. Positive ions are more likely to be N2+.

These charged air ions can be measured using sophisticated laboratory equipment. Measurement of these ions over the past few decades has revealed major differences exist between the air we breathe in a rural environment and the air we breathe in urban areas, especially indoors in urban centers. For example, a rural outdoor measurement would typically contain 2000 positive and 1500 negative ions per cubic centimeter of sampled air. An air conditioned data terminal center in the city contains on an average only 100 positive to 50 negative ions per cubic centimeter of sampled air.

The reason such a large disparity exists is generally due to the following factors:

1. Ducted air conditioning. The metal ducting attracts charged particles and the air is subsequently depleted of ions.

2. Static electricity, particularly positive voltage fields, attracts and degrades oppositely charged particles. Static charges are generated by VDTs, Synthetic carpets,furniture wall fabrics, and workers' clothing.

3. Smoke and air pollution. The localized effect of dust, smoke, and other materials act as a sponge to literally soak up airborne ions.

4. High density of individuals. Each individual removes ions from the air while breathing and each carries a certain amount of static electricity. The greater the concentration of individuals in a given air space the greater the likelihood of ion depletion.

Research has intensified recently regarding the possible health effects associated with ion depletion. This is due largely to findings of Prof. Albert Kruger (ref) and other noted scientists. Professor Kruger demonstrated that ions are biologically active. As such, they exert a direct impact on the body's ability to absorb oxygen into blood cells, oxidize serotonin in the blood stream and enhance or retard the body's efficiency in filtering airborne contaminants from lung tissue. His findings further isolated the negative ions as being productive to biological efficiency while the positive ions were generally found to be detrimental. The absence of either positive or negative charges in the breathable atmosphere resulted in death by suffocation to laboratory mice since their systems were unable to absorb nonionized oxygen.

Researchers in Russia (MINKH), Norway (HANS H. TJONN, M.D.), Israel (SULMAN, Ph.D), United States (ALEXANDER and FISHER, M.D.) and England (L. H. HAWKINS, Ph.D) are but a few who successfully linked the existence of air ion depletion to detrimental biological and behavioral effects in humans. Best known for studies relative to VDT operators was Leslie H. Hawkins, Ph.D., senior lecturer in human biology at the University of Surrey, Guildford, England. Dr. Hawkins conducted extensive double blind occupational studies to determine if positive and/or negative atmospheric ion levels could influence actual performance levels as well as attitudes among VDT operators.

The results of Dr. Hawkins' studies were published in the book Health Hazards from VDTs as well as a number of industry trade journals. He demonstrated that a majority of VDT operators (5:1) reported feeling more comfortable and alert when the deionized environment in which they had been working was replenished with a natural level of negative ions (anions). His studies also revealed that replenished anionic air increased work efficiency and productivity on the part of VDT operators with a concurrent reduction in reported symptoms of nausea, stress, fatigue, dizziness, etc.

Dr. Hawkins summarized his findings by acknowledging the fact that approximately 75 percent of all individuals are directly affected by severe changes in atmospheric ion balance. Further, he stated that VDT operators usually work in areas deficient in negative ions due to the static charge on the surface of their monitors which virtually annihilates the limited existence of available negative ions. He recommends that the introduction of artificially generated negative ions can significantly reduce complaint of illness, particularly headache, nausea, and dizziness while simultaneously improving the worker's subjective rating of the environment. He further found that negative ions improve certain types of psychological and psychomotor performance. Dr. Hawkins also cautioned maintenance of ion levels at the workstation should not be considered a total solution since other factors contribute to the complex nature of workplace safety. Human engineering, which deals directly with ion levels alone, has proven to substantially reduce illness and increase comfort and productivity among workers subject to such engineering.

Dr. Hawkins' studies demonstrate a significant reduction in ion levels near VDTs due to the high positive charge on the screen (figure 1). Where a large number of VDTs exist in a confined space, they collectively reduce ion levels of the total environment. More important is the fact that in the micro-environment in which the VDT operator is confined the depletion level is far greater than the room in general.

Distance from screen (meters)

Figure 1: Ion levels near a 14 inch screen with a surface charge of only +6 kv. The shaded area is the area in which most VDT operators position their head in relation to the screen.

The double blind procedure conducted by Dr. Hawkins consisted of installing negative ion generators in the work area and not allowing the subjects to know if the generators were on or off. The first four weeks consisted of ionizers installed but not working. During weeks 5 - 12, the ionizers were switched on, again unknown to the experimental design, thus insuring a double blind procedure. At the end of each week period, each subject completed a questionnaire. The incidence of reported headaches alone is shown in figure 2. Nausea and dizziness were reported as being proportionally increased when ionizers were turned off.

Figure 2: Effects of shift and ions on headaches. The incidence is expressed as the percentage of individuals in the group complaining at least once during any week.

Reported symptoms relative to facial rashes and eye irritation among VDT operators have been investigated by a number of respected dermatologists. Initially it was suspected facial skin symptoms and eruptions may be attributed to electromagnetic radiation from VDTs. However, Dr. Alexander A. Fisher, M.D., (ref) (clinical Professor of Dermatology at New York University Medical School) and Drs. R.J.G. Rycroft and C. D. Calnom (ref) (St. John's Hospital for Diseases of the Skin, London, United Kingdom) conducted case studies concluding that while a high number of facial rashes were present among VDT operators there was no evidence the rashes were being caused by electromagnetic radiation (EMR).

Studies conducted by Hans H. Tjonn, M.D. (Directorate of Labour Inspection, Oslo, Norway) investigated possible causes of reported VDT operator skin rashes from sources other than electromagnetic radiation. By placing a window glass shielding between the operator and the screen, doctors reported subjects did not experience less facial irritation. Placing a grounded conductive material between the VDT operator and the screen did prevent cases from developing an outbreak. Finally, replacing most items in the environment which were a source of static voltage buildup, such as synthetic carpets, prevented cases from occurring at all.

The results of these studies led the researchers to conclude that electrostatic phenomena in a series of VDT work areas demonstrated that rash-prone operators are commonly exposed to extreme electrostatic fields which are caused by the high voltage associated with the VDTs and by electric charges accumulated by the bodies of the operators. Subsequently, a precipitation of submicron particles to the skin of the VDT operators contributes significantly to irritation and occasional infection of the skin.

Mitigation techniques include elimination of all static voltage generating sources, neutralization of static potentials (grounding) or balancing of charges in a predominantly positive field potential (ion balance). Elimination of static generating devices is, of course, impractical in most cases. Installing a grounding shield between the VDT operator and the screen is possible using a conductive screen mesh which may also double as a glare filter. However, these techniques, while moderately effective, do not correct the problem of negative ion depleted air. To fully mitigate the problems produced by static charge build-up and its subsequent harmful effects, the more effective means of correction is to treat the atmosphere itself. Zenion Industries, Inc. of Rohnert Park, California, manufactures just such a device called the Screen ELFtm. It is an inexpensive electronic device which mounts directly on the VDT and provides a constant flow of negative ion-enriched air to establish an "air wall" between the operator and the VDT equipment. Using a unique, patented pulsed plasma energy source, the Screen ELF recirculates the workstation atmosphere without voltage build-up and oxidizes unwanted chemicals and many airborne bacteria.

A study conducted by Bruce L. Rosenberg of the Federal Aviation Administration (ref) confirmed that flight control operators overwhelmingly experienced the same symptoms currently being reported by VDT operators. Air traffic control operators, like VDT operators, are exposed to cathode ray tubes (CRTs) in the radar control centers around the country. Mr. Rosenberg endeavored to discover if the incident of stress, fatigue, and skin irritation, etc. could, indeed, be attributed to the excessive, self-induced ion imbalance produced by the equipment and other factors in flight control centers. His findings did, in fact, confirm previous isolated studies and resulted in his recommendation to regulate ion levels, particularly negative ions, in all flight control centers. He further recommended negative ion levels in atmospheres should not be allowed to drop below 500 ions per cubic centimeter of air and that this threshold standard should also be applied to commercial aircraft compartments.