Background:

The Cowichan Bay Volunteer Fire Department was founded in 1947. Between the years of 1947 and 1977 the CBVFD operated 5 different pieces of apparatus all in the traditional “Fire Truck” color of Red. When a new Pumper truck was ordered in 1977, it was delivered Lime Green (Optic Yellow) with a white upper cab due to new found evidence about safety and visibility.

Over the next 3 years the remaining 3 pieces of apparatus were also repainted to match the new color. Between 1983 and 1994 all additional apparatus were purchased, or painted, to match the new hi visibility, safer color scheme.

In 1996 the addition of a new Mini Pumper saw a shift in paint scheme from base Green with White cab top to a base White with Green (More yellow than the original color) Stripe. Each piece of apparatus purchased since 1996 has been purchased Base White with the Yellowish Green Stripe added (BMW Paint Code 101 – Safety Yellow). To date, the only apparatus still in the Original Green and White paint scheme is Rescue 43 which has been in service since 1994.

Other Emergency Services have also utilized lighter colors to improve safety. In 1992 the RCMP changed, from the traditional base Blue with a white door to the now recognizable all White vehicles. Since the inception of the Provincial Ambulance Service in 1974, when they took over from a variety of private and fire department run ambulance services, all their units were painted base white with a red stripe, a color scheme which is still used to this day.         

Why Green instead of Red?

In short, a 2009 study by the U.S. Fire Administration (USFA), a division of the Federal Emergency Management Agency (FEMA), concluded that fluorescent colors, including yellow-green and orange, are easiest to spot in daylight (3). Since the 1970’s there has been a lot of research into the Safety of Fire Apparatus and the visibility of apparatus when both travelling and working on roadways.

Researchers (and volunteer firefighters) Stephen S. Solomon, OD, an optometrist, and James G. King were aware of these perceptual differences when they analyzed accident data from the Dallas Fire Department. In the 1970s and early 1980s, Dallas started replacing its red fire vehicles with lime-yellow fire vehicles with white upper cabs. After the early 1980s, the fire department bought red vehicles with white cabs. During their four-year study published in 1995, Solomon and King found that the risk of a visibility-related, multiple-vehicle accidents may be as much as three times greater for red or red/white fire trucks compared to lime-yellow/white trucks. The results also showed that when lime-yellow/white fire emergency vehicles were involved in an accident, the likelihood of injury or tow away damage was less than for red or red/white vehicles involved in an accident. An earlier study by Solomon involving nine cities and 750,000 fire vehicle trips found that lime-yellow fire trucks were half as likely as red trucks to be involved in intersection accidents (3).

The Solomon and King research also found that the ancillary equipment and markings used to make fire vehicles detectable are not as effective as previously thought. These safety measures include flashing lights, strobe lights, retro reflective material, and audible alarms. Lime-yellow has been found to be a distinctive, highly visible safety color. Research reveals it can reduce or prevent serious fire apparatus accidents through early detection (4).​

The Human Eye:

A review of human visual color functions sets the stage for questioning the choice of red for fire vehicles. In the mid- 1800s, Helmholtz wrote about the human eye as red-weak. When human eyes are adapted to daylight (photopia), the color red is seen with much greater difficulty that are most other colors. At night, when eyes are dark adapted (scotopia), they are practically red-blind. Research found that certain colors can be seen farther into the visual periphery than others, thus offering earlier detection. Red has a narrow lateral range, whereas yellow’s range is much wider. It is also stated that color-defective individuals struggle with the color red but can see yellow much more readily. In fact, 8% of the male population is red/green defective; of this group, 25% are red-blind (10).

Figure 1 shows the sensitivity of the human eye to various colors in daylight and at night. During daylight, when we see primarily with the cones in our eyes, the human eye is most sensitive to yellowish-green light (the dashed line in the figure). At night, the human eye is most sensitive to green light (the dotted line). Whether night or day, the human eye is simply not very sensitive to red lights and objects. In fact at night, sensitivity to red is near zero! So while red objects do indeed tend to stand out against most backgrounds in the real world, they are darned hard for the human eye to see. In fact, at night without streetlights for illumination, a red fire engine is virtually invisible! And to make matters worse, 7-10% of men (0.4% of women) have red-green color blindness. For them, red looks like a dull gold color (11)

The Science – Red versus Lime-Yellow

Several studies have shown that lime-yellow is more effective in attracting human attention than red. One investigation indicated greenish-yellow and yellow are the band of colors to which the human eye is most sensitive. Human vision does not see red when the eye has adapted to darkness and sees red only poorly when it has adapted to bright light. Research has found that “lateral peripheral vision for detecting yellows is 1.24 times greater than for red.” One-fourth of the 8 percent of the male population with red-green color vision deficiencies cannot see red at all. Finally, a 1959 study concluded, “Golden yellow . . . [is] the most easily visible color for both normal and color deficient groups under all testing conditions.” Separate studies revealed light colors such as yellow and white are the most easily seen against the background of a well-worn highway; and red-and-white stripes decrease the visibility of a vehicle, while yellow-and-black stripes increase contrast and visibility (5).

The use of contrasting colors can positively affect conspicuity by assisting drivers with locating a hazard amid the visual clutter of the roadway. There are basically two types of contrast:

1) Luminance contrast — the degree to which an object is brighter than its background, and

2) Color contrast — the difference in an object’s color(s) and those found in its background.

Contrast is enhanced by using colors not normally found in the environment, including fluorescents. Fluorescent colors enhance daylight conspicuity. The specific color choice may or may not be important with respect to fluorescents, perhaps depending on background characteristics. In a 1994 study, “…fluorescent yellow was found to be best detected and fluorescent orange was found to be best recognized against any of the three backgrounds investigated.” A recent study of traffic safety garments showed no statistical difference in the daytime conspicuity of fluorescent red-orange and fluorescent yellow-green, although fluorescent yellow-green had a significantly higher luminance value, compared to the background, than the fluorescent red-orange (6).

Conclusion:

Yellow-green lime shades are the easiest, most noticeable colors for humans to see, including at night (7). Studies have documented Red vehicles are 10% more likely to be involved in an accident in daylight hours and 50% more likely to be involved in an accident during darkness versus yellow vehicles (8). The use of retro reflective materials to improve conspicuity of emergency vehicles is recommended but does not equal the visibility of lighter or brighter colors. Visibility and recognition are both importance for emergency vehicle conspicuity. Contrasting colors can help drivers locate a hazard on the road, a vehicle that stands out against its backdrop is far more “visible” to other drivers. Fluorescent colors (i.e., fluorescent yellow-green and orange) have higher visibility during the day than Red (9). Europe is known for its highly conspicuous emergency vehicles, especially Police and Ambulance, however the Australian Capital Territory Fire & Rescue (ATCF&R) is probably the most prominent in the Fire Service since switching from the traditional Red to High Visibility Fluorescent Yellow-Green in 1992. Now its entire fleet of Fire Apparatus covering 9 stations sport the combination of Yellow-Green base color and 360° of Retro Reflective striping for the ultimate in safety.