Computers and Video Display Terminals

Direct source of pollution
Indirect source of pollution
Computers and VDTs as victims

Computers and video display terminals (VDTs) may seem like unlikely sources of indoor air pollution, but they do contribute in several ways.

Direct Source of Pollutants 

Computers and VDTs can emit ozone and off-gas volatile organic compounds (VOCs). The greatest amount of VOC off-gassing is around 175 µg/hr and goes down quickly within the first 300 hours of use.¹ In their proposed regulations to improve indoor air quality, the Occupational Safety and Health Administration listed the following chemicals as being emitted by computers and VDTs:²

• n-Butanol
  

• 2-Butanole
  

• 2-Butoxyethanol
  

• Butyl-2-Methylpropyl phthalate
  

• Caprolactam
  

• Cresol
  

• Diisooctyl phthalate
  

• Dodecamethyl cyclosiloxane
  

• 2-Ethoxyethyl acetate
  

• Ethylbenzene
  

• Hexanedioic acid
  

• 3-Methylene-2-pentanone
  

• Ozone
  

• Phenol
  

• Phosphoric Acid
  

• Toluene
  

• Xylene

Though none of these chemicals from computers is likely to be measured in quantities that would exceed any established workplace health and safety limits, the unknown factor is how some of these chemicals may interact with each other to cause problems many years in the future. In addition, there are no established health and safety limits for exposure to chemicals for those whose bodies may be more vulnerable such as growing children, people with existing diseases, and the elderly.

However, one chemical that has recently received attention with computers is triphenyl phosphate, which is widely used as a flame retardant in the plastic of video monitors. Triphenyl phosphate is known to cause allergic reactions in some people such as itching, nasal congestion, and headaches. One study found that though emissions of triphenyl phosphate dropped off sharply after the computers were run for eight days continuously, there were still elevated levels in the air for 183 days. This translates into about two years of normal use.³

Computers also emit electromagnetic fields (EMFs) and many experts feel that people should limit their exposure to these fields. In a study done by Reading University, researchers found that more than one-third of sick building syndrome also know as building-related symptoms, were caused by low-frequency electromagnetic radiation from computer monitors.⁴ Other scientists say that because of all electrical appliances in bedrooms, people sleep with a body voltage 30 to 60 times higher than what is normally found in nature. This may cause insomnia, sore muscles, anxiety, chronic fatigue, and possible cancer.⁵ As a result, computers should be placed in other areas of the home in order to minimize the number of electrical appliances in the bedroom.

Indirect Source of Pollutants

Health effects such as irritated eyes, nose and throat and dry skin are more common among workers in offices with computers.⁶ In particular, surveys of office workers in the US have found that eyestrain tops the list of health problems. This affects over 40 percent of all computer users and increases with the amount of time spent working at the computer.⁶ There are two reasons why people's eyes may bother them more when they are working at computers:

1. People do not blink as much when they work at the computer. Every few minutes you are working at a computer, you should stop and look at something in the distance for about 20 seconds.

2. The electromagnetic fields of the computer screen increases the number of particles in the air near the screen since the particles are attracted to the computer screen and/VDT just like dust is attracted to the screen of your TV set at home. This increase in particles makes the chances greater that these particles might land on the person's face and in their eyes as they use the computer. These particles can contribute to "office eye syndrome."⁷ This is especially a problem if the computer and/or VDT user wears contact lenses. In 1997, a study found that the people most at risk for building-related symptoms were clerical workers who wore contact lenses and worked in front of computer screens in mechanically ventilated buildings. Airborne bacteria became electrically charged and settled either on the computer and/or VDT screens or on their contact lenses.⁴

Computers and/or VDTs use may also increase job stress, which is often associated with increased sensitivity to the work environment and more building-related symptoms complaints.⁶ Studies have found that people who spend more than four hours per day at computers and/or VDTs have 20 percent more lost sick days due to building-related symptoms than people who do not use computers or VDTs as much.⁷

Computers and VDTs as Victims

Computers and VDTs also can be harmed by poor indoor environments. If nothing else, indoor environments often have to be kept within certain temperatures and humidity ranges, in order for the computers to work properly. For example, one time in a state office building in New Jersey in the early 1990s, the building's air-conditioning system broke down during the summer. When the temperature in the building reached 95° F, workers were asked to turn off their computers so that they would not overheat. The employees, however, were still expected to work even though there was no ventilation and the windows did not open.

Excessive dust can destroy computer hard drives and the same VOCs that can hurt people can harm expensive equipment. Volatile organic compounds can create a film that covers computer circuit boards that causes them to blink or break down.⁸

References

1. Hetes R, Moore M, Northelm C. Office equipment: Design, indoor air emissions, and pollution prevention opportunities. US EPA Project Summary, EPA/600/SR-95/045; Research Triangle Park, North Carolina. 1995.

2. OSHA: Indoor Air Quality Proposed Regulations: Federal Register 59: 15968-16039, April 5, 1994, Table 3-2: www.osha-slc.gov/FedReg_osha_data/FED19940405.html.

3. American Chemical Society. Chemical found In computer can cause allergy, sickness. Science Daily. September 19, 2000: www.sciencedaily.com/releases/2000/09/000919080653.htm.

4. Sieveking P. Strange but true: When the blue mist swirls. Sunday Telegraph (London). August 15, 1999;14.

5. Templeton F. A Healthy House. Country Living. June 1996;66-72.

6. Hedge A. Where are we in understanding the effects of where we are. Ergonomics. 2000;43(7):1019-1029.

7. Levin H. "Physical factors in the indoor environment." Occupational Medicine: State of the Art Reviews. Philadelphia, Hanley and Belfus, inc. 1995 Jan-Mar;10(1):91.

8. Conlin M, Carey J. The business case for better indoor air quality. Business Week. 2000;5:114