Jonathan Gordon, Marketing Manager, Fire & Rescue at Nightstick, sheds light on visibility in firefighting

Light and vision are tightly linked.

Our eyes have adapted over time to develop ways to see in various lighting conditions.

Low-light environments create special difficulties, especially in high-pressure situations like firefighting.

Staying safe and effective in these scenarios require an understanding of how our eyes work.

How light behaves, or fundamental light behavior, guides advanced lighting system’s design.

It is crucial to see how these systems are influenced by, and how they enhance, the human eye’s structure.

This column takes a dive into how our eyes function in low-light conditions and modern LED lights in fire safety.

By explaining how our eyes and light work, we journey through the science-backed reasons for the development and effectiveness of tools like Nightstick’s exclusive Dual-Light™.

As we stand at the intersection of biology and technology, let’s explore how optimised LED lighting strengthens not only visual clarity but also the overall safety of firefighting operations.

Human vision in low-light conditions

When lighting is not ideal, our eyes work hard to see using the little light that is available.

This incredible feat relies heavily on the complex design of the visual system.

Rods in our eyes help us see in low-light.

They are special light-sensitive cells around the edge of our retinas.

Unlike their cousins, the cones, which help us recognise colors under bright conditions, rods are exceptionally sensitive to dim light.

When light strikes these rods, a pigment called rhodopsin undergoes a transformation, initiating a stream of reactions that send electrical signals to our brain.

It’s because of rhodopsin that we can see at night, but only in shades of gray.

Vision in dark and smoky environments

In low-light situations, our eyes rely on peripheral vision—the edges of our sight—to detect movement and give a wider view of our surroundings.

This is especially crucial for firefighters, as it helps them spot potential hazards or sudden movements when they’re focused on a task.

Another essential skill in these conditions is being able to distinguish objects from their background, such as seeing a squad member in a smoke-filled room or identifying a fallen item.

Known as contrast sensitivity, this ability aids firefighters to act quickly when each moment counts.

The dark adaptation process

Transitioning from a well-lit environment to darkness is no small feat for the visual system.

As we move to dimmer surroundings, the eyes undergo a process known as dark adaptation.

During this phase, the amount of the restored rhodopsin in the rods increases, gradually enhancing our sensitivity to low light.

However, this transition isn’t immediate.

It’s why firefighters, when moving from a bright exterior to a dimly lit building, might initially struggle with visibility, only to find their vision improving over the span of a few minutes.

The science of LED lighting

Light isn’t just what our eyes see—it’s part of a bigger picture.

Light can behave in different ways:

Reflection: Think of how light bounces off a mirror.

That’s reflection.

Refraction: When light passes through water and seems to bend, that’s refraction.

It’s why a straw looks bent in a glass of water.

Dispersion: sometimes, light splits into different colors, like the way we see a rainbow after rain.

That’s dispersion at work.

Knowing these rules are critical in making effective LED lights.

They’re designed with these behaviors in mind, making sure we see well, even in tough situations.

A key point: our eyes are especially good at picking up the color green when it’s not very bright around.

That’s why Nightstick uses a green “Find Me” feature on the rear of LED lights.

In smoky, hazy conditions, this green light stands out above others, helping firefighters spot their team more easily.

Precision and spread in light management

The lighting tools we deploy can mean the difference between safety and hazard.

The two primary players in this narrative are spotlights and floodlights, each with its unique approach.

The duality between spotlights and floodlights emerges from the way they manage light.

Spotlights: These lighting tools project a focused, narrow beam of light.

The core of a spotlight lies in its ability to minimise the spread or divergence of light rays.

By using parabolic reflectors (curved mirrors), spotlights concentrate the light, guaranteeing it travels mostly in parallel rays.

This setup ensures that the light is intense and can cover long distances effectively, cutting through obstacles like smoke or haze.

Given their penetrative nature, spotlights are irreplacable in scenarios where pinpoint accuracy and reach are paramount.

In contrast, floodlights cast softer light over a large area.

They operate by spreading light rays rather than focusing them.

The wide-angle dispersion of light projecting from floodlights is achieved through specially designed reflectors or diffusers that scatter light in multiple directions.

This scattering confirms that while the light covers a broad area, it won’t be as intense at any specific point as a spotlight would be.

Floodlights excel in situations where an overall view of a close-range area is more critical than distance or intensity.

The angles and intensities in LED lighting aren’t mere design choices; they’re grounded in optical physics.

When floodlights are placed at a 45-degree angle in Nightstick’s Intrant® angle light, for instance, it isn’t without purpose.

This specific angle minimises the chances of light reflecting directly into the eyes, reducing glare.

Furthermore, by illuminating the ground, it highlights potential obstacles, thereby preventing mishaps like trips, slips, and falls.

Spreading light can also reduce shadows that may otherwise hide potential hazards, key for firefighter safety.

Through harnessing these principles of light, certain innovative systems like the Dual-Light™ are making strides in the firefighting field.

Banishing shadows and balancing vision

In the fast-paced world of firefighting, where split-second decisions can be life-altering, the cross play between vision and light becomes vital.

The Dual-Light™ system blends how light behaves using lines and angles with the natural abilities of the human eye for a balanced effect.

The Dual-Light™ system uses both focused spotlight and wide, unfocused floodlight.

By emitting light in two distinct directions – a focused beam for distance and an unfocused one for a broader view – it provides comprehensive coverage of the environment.

The system provides a surge of confidence from visibility while staying protected from surrounding hazards.

When both the spotlight and floodlight function simultaneously, the outcome isn’t merely doubling the light; it’s synergistic.

The focused beam from the spotlight draws attention to specific points of interest, while the floodlight bathes the surrounding area in light.

It’s like having natural light with a bright center and clear edges, thereby enhancing situational awareness.

One of the innate challenges with focused spot lighting is the creation of sharp shadows around the illuminated area.

These shadows, particularly in high-pressure environments, can be misleading and dangerous.

When the floodlight complements the spotlight, it fills in these shadows, reducing contrast and providing a uniform illumination.

By harmonising these two sources, the Dual-Light™ system makes sure that objects close to the target, which might otherwise be obscured, are easily visible.

This harmony plays an important role in environments where the ability to tell apart different shades of color becomes essential.

The Dual-Light™ system doesn’t merely light up an environment; it does so in a manner that is customised to human vision.

By providing both detailed and peripheral views, it caters to the eye’s natural strengths in low-light conditions.

This intentional design, built on the foundation of both optics and biology, enables the firefighter to remain focused, prepared, and safe during operations.

Illuminating the path forward

In the firefighting arena, every tool, strategy, and piece of knowledge is a lifeline, and light stands at the forefront of this arsenal.

The connection between the human eye and man-made LED lighting is as complex as it is essential, covering the landscapes of biology, physics, and technology.

The dive into human vision under low-light conditions unveils an astounding interplay of cells, pigments, and neural pathways, all fine-tuned over time to draw clarity from obscurity.

By comparing our eyes to how light behaves, we see why spotlights are narrow and floodlights are wide.

With modern advancements like the Dual-Light™ system, a harmonious marriage of these two realms is formed, illustrating a testament to human ingenuity – the ability to spot our natural strengths and design gadgets that take us to new levels.

As with all fields driven by innovation and need, being passive is not an option.

Nightstick’s effective Dual-Light™ system signifies just one milestone in the ongoing journey of enhancing fire safety.

The path forward calls for a continued commitment to research and study of how vision and light work together.

Every ray of light engineered, every shadow diminished, and every issue understood, inches us closer to ensuring the safety of those who stand as our protectors against the flames.

After all, in the quest to enhance tools and technologies, we aim to safeguard every firefighter – the valiant guardian facing the inferno.

This article was originally published in the November 2023 issue of International Fire & Safety Journal. To read your FREE digital copy, click here.