Why The Hospital Won't Let You Call

As a teenager, you've probably been admitted at to a hospital at one time. During this time, you must have known what people mean when they say that hospital ceilings are boring. You also probably noticed the several signs requesting patients and their visitors not to make phone calls whilst in or around the ward area. Why so? Two words: electromagnetic interference. Find out what this is, what it does and what can be done to reduce chances of its occurrence.

What It Is And What It Does Like many other appliances, your phone emits electromagnetic waves. These waves have the ability to travel through a vacuum and they result from vibrating electrical charges. You've seen the kind of machines and equipment used in hospitals. These machines have complex in-built electrical circuits that facilitate their operation. They're also often connected to computerized monitoring systems via a network of cables that transmit data to this system for interpretation. Damage to the in-built electrical circuits affects the performance of hospital equipment and severe damage poses the threat of equipment failure.

Electromagnetic interference would occur when waves generated by your phone create a disturbance that affects the in-built circuits or data transmission in the cables that connect to the monitoring system. The shorter the distance between your phone and the cables/equipment in question, the greater the interference. The reverse is also true. With moderate interference, the efficiency of hospital equipment could easily be compromised. With severe interference (e.g. if multiple phones are used simultaneously), the operation of such equipment could easily grind to a halt. This explains the policy that prohibits use of mobile phones in or around the ward area.  

Taming Electromagnetic Interference In addition to the 'no calls' policy, hospitals take other precautionary measures aimed at reducing the likelihood of interference. For example, installation of data cabling systems around hospitals is done such that data cables and cables that carry electric power are placed as far as possible from each other in relation to the amount of space available for installation. A hospital may also attempt to minimize chances of interference by specifying the use of shielded cables for both electrical systems and data cabling systems installed around/within their premises. Shielded cables have a protective barrier made using a magnetic material (in the case of data cables) or an electrical conductor (for power cables). The barrier reduces the strength of electromagnetic fields around the cables, thereby reducing the likelihood of interference. Now you have a legitimate answer for anyone who asks why you couldn't call to say that you were in hospital.