Why the knowledge of color-coding is essential for us

You must have seen this gripping scene in many action movies, where the protagonist or cop fumbles with one wire in an explosive to defuse it! In Bollywood it is usually more dramatic and they may even prolong the scene with dialogues, emotion, visuals of ticking lock etc. till the bomb is in the verge of explosion. The confusion of “blue or red”, is the pinnacle of built-up tension on the silver screen. It is indeed a moving scene, especially if the explosives are attached to the body of a child (ie. Rush Hour 2), but what this scenario also subtly teaches us is the critical learning about color codes, that we lack in the current education system.

Color coding (and decoding them) has been our survival instinct from the beginning of mankind. It is also an integral part of our socio-cultural norms. The newly married Hindu bride wears a lot of red (in form of bindi, bangles, costumes, clothing etc.) and the widows traditionally wear a lot of white. Similar coding exists among various religions in India. Even, the food has a lot of interesting color codes which impacts us subconsciously. For example in India, if a food is meant to be ‘spicy’ (masaladaar) it has to appear predominantly red. The color code of ‘redness’ not only reflects the cognitive feeling of ‘spiced up’ but also brings in the coded meaning of celebration, passion, and aggressive divinity.

In our daily life, color codes exist right from electrical circuits to structural engineering and even in medicine. The famous/ infamous ‘red pill vs. blue pill’ theory is a classic indication of color coding in medicines. In medicine, color coding is the systematic, standardized application of a color system to classify and identify products, generally within the same pharmacologic class. Such systems allow people to match particular colors to specific functions. The majority of research in this area has focused on the use of color-coding to reflect different levels of implied hazard. As research suggests, red is perceived to represent a high hazard level. The Institute for Safe Medication Practices Canada has recommended the use of red packaging and labeling for neuromuscular blocking agents. Another example that will be familiar to many readers is the requirement to use black-cap packaging for potassium chloride concentrate. All manufacturers must now follow this directive because of the high potential risk that concentrated potassium chloride poses to the patient. Color-coding systems are common in other areas of health care. For example, wristbands in standard colors have been used to identify patients with specific conditions (e.g., allergies). These wristbands help to prevent confusion that could lead to medication errors, misidentification, and death. Anesthesiologists in the United States, Australia, New Zealand, Canada, and Great Britain have adopted a color-coding system for user-applied syringe labels for anesthetic drugs. Although the intention is to reduce the risk of error due to accidental syringe swapping, evidence for the effectiveness of this strategy is limited and mixed. The American Academy of Ophthalmology has recommended a uniform color-coding system for the caps and labels of all topical ocular medications. Color matching uses color to safely match one item to another. For example, a medical device may have a blue plug that inserts into a blue receptacle, a yellow plug that inserts into a yellow receptacle, and so forth. This technique has been used to match the length of a child (for an accurate estimation of weight) to a color zone corresponding to appropriate drug doses, appropriate sizes of commonly used equipment (such as endotracheal and nasogastric tubes), and appropriate IV fluid volumes. The use of such a tool was associated with a significant reduction in deviation from recommended doses in simulated pediatric emergencies. Colour differentiation involves the use of color to enhance features on labels and packaging, to help users discriminate one drug or product strength from another. The use of this color technique enhances the noticeability of a label by increasing the speed and accuracy of label identification and the perceived readability of labels.

The depiction of body and anatomy in medical science and physiology is also color-coded. For Gross Anatomy the muscles are colored as brown, artery as red, vein purple, nerve yellow, lymph nodes as grey, bone in black, fascia and ligaments in green.

Color coding even exists in computer science. For example, the hex-code #451208 signifies death because the letter D is the 4th letter of the alphabet, E is the 5th, A is the 1st, and so on spelling out "death". Also, the color it produces is equally sad and spooky (dark brown with dark grey values).

Understanding the color-coding in the electrical wire is very crucial and a mistake can lead to large-scale disaster/ accident. Wiring for AC and DC power distribution branch circuits are color-coded for the identification of individual wires. In some jurisdictions, all wire colors are specified in legal documents. In other jurisdictions, only a few conductor colors are so codified. In that case, local custom dictates the “optional” wire colors. Most of Europe abides by IEC (International Electrotechnical Commission) wiring color codes for AC branch circuits. The United Kingdom now follows the IEC AC wiring color codes. The US National Electrical Code only mandates white (or grey) for the neutral power conductor and bare copper, green, or green with a yellow stripe for the protective ground.  In three-phase power supply, the combination of Black, Red and Blue wires for power conductors are used for 120/240V AC whereas the combination of Brown, Orange and Yellow wires for power conductors are used for 277/480 V AC. In case of single phase power supply, Black wire is used as the line wire and in case of 220V supply, Red wire is used as the secondary line conductor. In India, we follow the standard for electrical wiring color code. According to its old standard, red is used for live (or line) power conductors, black for neutral and green for protective earth or ground. However, currently, it is slightly modified to follow the RGB mode. Red wires are live wires, green wires are used for grounding, black wires are neutral, blue and yellow wires are used to connect with live wire.

Today, even residential areas are getting color-coded depending upon the infection intensity with Covid 19, the “Red zone, Orange zone vs Green zone’. However, interestingly, the dead bodies of covid affected individuals are wrapped only in ‘white’, a presumably neutral color that may not offend any religious belief.

However, the modern education system in Indian schools (elementary and secondary level) has no input in color or color-coding. The subject itself is not introduced until one reaches to specialization at graduation (in niche domains). This illiteracy leads to widespread disasters. The below visual of individuals standing in queue to fill oxygen in the empty cylinders prompted me to write about the importance of color coding in the gas cylinders. This issue is not being discussed anywhere and amid the oxygen crisis, the caregivers are desperately pulling any cylinder available to fill/ give oxygen to the Covid affected patients. It is indeed dangerous to fill oxygen in any color-coded cylinder as the gas residues inside the cylinder can get mixed with filled oxygen and may react while administrating the same to patients. The medical Oxygen cylinders always come with a white top and black body. The yellow top is mostly demarked for the toxic/ corrosive gases and red cylinders are supposed to carry inflammable gases! This is why the knowledge of color coding through the education system is crucial as we lack such general awareness among the public in India.

As Dr. Deepak has mentioned, Color coding is helpful in the identification of gas cylinders and lines even by laymen provided they are familiarised with such color codes. Almost all countries follow their own guidelines but efforts have been made to prescribe universal color-coding. British Compressed Gases Association introduced cylinder identification and color coding scheme through BS EN 1089 – 3 which has been harmonized in the European Union. The colors used for medical gases are harmonized on the basis of ISO 32 standard

The color coding is applied to the shoulder or the curved portion of the cylinder and it identifies the property of the gas inside the cylinder.

• Yellow – toxic
• Red – flammable
• Light blue – oxidising
• Bright Green – inert

A gas cylinder having two concentric color bands indicates a combination of properties. The body of the cylinder can be of any color of the manufacturer’s choice but it should not lead to confusion regarding the risk associated with the gas as indicated by the shoulder color.

For the purpose of easy identification and the shoulder, colors can refer to the gas inside the cylinder. Some typical examples are:

• Maroon – acetylene
• Grey – carbon dioxide
• Brown-helium
• Red – hydrogen
• Blue – Nitrous oxide
• Black – nitrogen
• White – oxidant.

Such codes are essential to display across medical facilities, however, I have not seen such practices anywhere in India.

(Original article on color-coding by Dr. Kaustav SenGupta, 21.05.21. No part to be published without permission)