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Red or blue? - The dilemma of color coding information messages to elderly

What color provides a reliable message without generating unnecessary panic but necessary alertness, just in case?

While developing the CleverGuard application, we encountered this dilemma that targeted the elderly living alone at home and their relatives and caregivers. CleverGuard brings insights into seniors’ habit changes in a non-intrusive way, supporting them to stay longer at home independently and fostering meaningful discussions between seniors and their carers. CleverGuard uses Non-Intrusive Load Monitoring (NILM) technology to track the habit changes of the elderly.

Please, help our work with your opinion and take a short anonymous survey about what colors mean for you for the sake of our research: Click to start the survey!

Should we use RED or BLUE colors while conveying messages if the habits of the elderly significantly deviate from the usual?

Here are the criteria we considered:

  • Which are the colors which people associate with specific conditions the most easily?

  • Which are the ones that do not generate unnecessary panic? e.g., the elderly is away from home, enjoying life with friends on a beautiful picnic in the park.

  • Which colors can be associated with a necessary level of alertness, just in case someone would not use electrical appliances due to a severe injury?

The standards

As several engineers within our multidisciplinary team of experts, we grabbed for standards first. There are several international standards for color coding of information messages, including:

  1. ISO 3864-1:2011: This standard specifies the design and use of safety signs, including colors to be used for different types of safety signs. It defines four primary colors for safety signs: red, yellow, blue, and green, with each color representing a different type of message.

  2. ANSI Z535.1-2017: This standard is similar to ISO 3864-1, but it is specific to safety signs used in the United States. It also specifies using four basic colors for safety signs: red, yellow, blue, and green.

  3. OSHA Standard 1910.145: This standard is a US Occupational Safety and Health Administration regulation that requires employers to use safety signs and tags to warn employees about potential hazards. The standard specifies the colors that should be used for different types of messages, including red for danger, orange for warning, yellow for caution, green for safety, blue for information, and purple for radiation hazards.

  4. IEC 60417: This is an international standard for graphical symbols, including color codes for different types of information. It specifies colors for different types of information, including red for danger or prohibition, yellow for caution, blue for mandatory actions or information, green for positive actions, and black and white for contrasting text.

Here is a simplified summarised description of the usual meaning of red or blue by the various standards for the most critical messages:


Red is a highly visible color commonly used for safety-related applications, including safety signs, labels, and markings. According to various international standards, red is typically used to indicate the following:

  • Danger or warning: Red is often used to indicate an immediate danger or warning, such as the presence of hazardous materials, high voltage electricity, or fire hazards.

  • Stop or prohibition: Red is commonly used to indicate a stop or prohibition, such as stopping at a red traffic light or not entering a prohibited area.

  • Emergency: Red is also frequently used to indicate an emergency situation, such as the location of emergency equipment or exits.


Blue is a commonly used color for safety-related applications in various international standards. According to these standards, blue is typically used to indicate the following:

  • Information: Blue often indicates information or instructions, such as signs that provide directions or guidance.

  • Mandatory action: Blue can also indicate a mandatory action, such as wearing personal protective equipment or adhering to certain procedures.

  • Safe conditions: Blue can indicate a safe condition, such as the location of safety equipment or emergency exits.

It's worth noting that while red or blue are typically associated with usual messages, its specific meaning can vary depending on the context and the standard being used. Different standards may also have different recommendations for using red or blue, as well as other colors, for safety-related applications.

Accessibility for color blind

Additionally, color blindness can affect a person's ability to interpret specific colors, so it's essential to use additional cues, such as shapes and text, to convey information.

Color blindness, or color vision deficiency, is a condition that affects the ability to distinguish between specific colors. The most common form of color blindness is red-green color blindness, which affects the ability to distinguish between shades of red and green.

The prevalence of color blindness in the general population varies depending on the specific type of color blindness and the population being studied. According to the National Eye Institute, about 8% of men and 0.5% of women with Northern European ancestry have red-green color blindness.

In the elderly population, the prevalence of color blindness may be higher due to age-related changes in the eyes. According to a study published in the journal Ophthalmology, the prevalence of red-green color blindness among people aged 65 and older was about 13% for men and 0.8% for women. The study also found that the prevalence of blue-yellow color blindness, which is less common, was about 3% for men and 0.2% for women.

Overall, color blindness is a relatively common condition, affecting a significant proportion of the population, including the elderly. However, most people with color blindness are still able to function normally in daily life and work, and there are many tools and techniques available to help people with color vision deficiency, such as color-correcting lenses and software.

So red or blue for CleverGuard users?

One thing is sure, we need to use icons that guide them. To help ensure that information icons are understandable for elderly people, it is essential to consider several factors and to design clear, simple, and intuitive icons. Testing colors and icons with elderly people in the target audience can also help identify potential issues and make adjustments to improve their understanding. Additionally, providing context and using multiple modes of communication, such as text and images, can help to improve the understandability of information icons for elderly people.

Your opinion matters!

What do colors mean to you? Please answer the following short anonymous survey


CleverGuard brings insights into seniors’ habit changes in a non-intrusive way, supporting them to stay longer at home independently and fostering meaningful discussions between seniors and their carers.

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