Category Archives: Helmets

The fallacy of the cracked helmet

Abstract

Intriguingly, a cracked bicycle helmet is often perceived as unequivocal proof of saving lives, but this is far from the truth. It is a sign of the helmet’s failure when the underlying styrofoam fails to compress. 

It’s a natural inclination to credit a helmet with saving us, but that doesn’t necessarily make it true. Without a helmet, cyclists get hit by cars, and the survival rates remain comparable.

It’s worth noting that our confidence in the protective power of polystyrene helmets often surpasses the stark reality. In a severe accident, these helmets frequently fall short in offering adequate protection.

Wearing a helmet can encourage riskier behaviors, increasing the risk of accidents and injury. The belief in helmets’ protective powers can foster a false sense of security.

Does the low-impact protection compensate for the increased risk of accidents?

That’s a question that deserves careful consideration.

_____

When we see a cracked helmet, it’s tempting to believe it’s irrefutable evidence that it saved a life. However, let’s delve deeper into the reality: a cracked helmet is, in fact, a sign that it has not functioned as intended. As experts advise, the key test is not in the cracks, but in whether the styrofoam has compressed. If it hasn’t, you can reasonably conclude that it hasn’t saved a life.

soft-shell-helmet A bicycle helmet is a piece of polystyrene covered by a thin layer of plastic.
Notice how the helmet has cracked, but the polystyrene did not compress.
This indicates the helmet failed to absorb the energy of the impact.

Polystyrene-based helmets protect by absorbing impact energy through compression. In severe accidents, they often break into pieces. If the helmet has cracked but failed to compress, it has, unfortunately, failed to absorb the energy of the impact.

It’s crucial to remember that a  bicycle helmet essentially consists of a piece of polystyrene concealed by a thin layer of plastic. This is where the problem lies – the helmet may crack, but the polystyrene might remain uncompressed, indicating that it failed to mitigate the impact.

Often, a cracked helmet has failed to work as intended:

“The next time you see a broken helmet, suspend belief and do the most basic check – disregard the breakages and look to see if what’s left of the styrofoam has compressed. If it hasn’t  you can be reasonably sure that it hasn’t saved anyone’s life.“

Correlation is not causation

Our inclination is to attribute causation based on timing. If we see a cracked helmet and remain unscathed in terms of head injuries, we instinctively link this to the helmet’s protection.

It’s a natural inclination to credit a helmet with saving us, but that doesn’t necessarily make it true. Without a helmet, cyclists get hit by cars, and the survival rates remain comparable. The majority of bicycle accidents do not result in serious head injuries, regardless of whether helmets are worn. We often overlook this, attributing a lack of head injury to the helmet:

“see the double-standard of finding it entirely logical when helmeted cyclists who survive collisions report that wearing a helmet saved their life. It is a powerful emotional argument, but logically, statistically, and scientifically, it is erroneous for the same reasons it would be erroneous to say that not wearing a helmet saved Gene Hackman’s life. If a cyclist wears a helmet and they emerge from a collision alive, that implies correlation, not causation.”

Polystyrene helmets are designed for low impacts

It’s essential to understand that bicycle helmets are designed to protect in minor impacts, not in high-impact scenarios, such as those involving motor vehicles. In such cases, the forces at play are generally beyond the protective capabilities of helmets. 

It is easy to forget that bicycle helmets are only designed to protect in minor impacts:

“In cases of high impact, such as most crashes that involve a motor vehicle, the initial forces absorbed by a cycle helmet before breaking are only a small part of the total force and the protection provided by a helmet is likely to be minimal in this context. In cases where serious injury is likely, the impact energy potentials are commonly of a level that would overwhelm even Grand Prix motor racing helmets. Cycle helmets provide best protection in situations involving simple, low-speed falls with no other party involved. They are unlikely to offer adequate protection in life-threatening situations.“

Dr Carwyn Hooper from St George’s University in London reports:

“Looking at evidence, it does not matter if people are wearing a helmet or not, any serious accident on a bike is likely to kill them”

In fact, polystyrene helmets can increase the risk of neck injuries and exacerbate brain injuries, with no guarantee of less severe head, neck, or brain injuries in a fall.

Wearing a helmet can encourage riskier behaviors

Adorning a bicycle helmet certainly instills a sense of safety and protection. However, it’s essential to recognize that this perception of invincibility can inadvertently lead us and those around us to engage in riskier behaviors. This, in turn, significantly elevates the likelihood of accidents and injuries. For instance, In Australia, cycling injuries tripled after a helmet law was introduced.

cycling_injury_rate

 In Australia, cycling injuries tripled after the helmet law.

How could the widespread use of helmets increase the risk of injuries? This can be attributed to the well-documented concept of “risk compensation.” As we feel safer, we tend to take more risks, resulting in a higher incidence of accidents.

Consider both benefits and risks

Helmets can mislead us. Cycling is inherently safe, with a severe head injury occurring once every 8,000 years of average cycling. However, wearing a helmet can paradoxically heighten the risk of accidents. Employing a device that increases the risk of accidents might not be the most effective strategy for enhancing safety. It’s ironic that a cracked helmet is celebrated as “proof” of saving a life when the accident itself might not have occurred without it.

It’s easy to be misled, especially in the aftermath of a traumatic experience. Realism about the capabilities of helmets is essential, grounded in facts. Overestimating their protective potential can, in fact, be perilous. After a severe accident, it’s too late to discover that bicycle helmets are not designed to protect against significant impacts.

Bicycle helmets can be insidious:

  1. At first, they seem to protect.
  2. However, they increase the risk of accidents and injury.
  3. They are inadequate in severe impacts..

Does the low-impact protection compensate for the increased risk of accidents?

That’s a question that deserves careful consideration.

What do you think of this post?
  • Insightful (18)
  • Interesting (8)
  • Boring (6)
  • Useful (5)

5 ways wearing a bicycle helmet can result in injuries

We tend to be less cautious

Wearing a safety device creates a feeling of safety. This makes us less cautious. This well documented behavior is called risk compensation. We tend to take more risks when wearing safety equipment.

risk-compensationRisk compensation is the tendency to take more risks when wearing safety equipment.

The New York Times reported an odd increase in injuries after bicycle helmets became popular in the US:

the rate of head injuries per active cyclist has increased 51 percent just as bicycle helmets have become widespread. …

the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks. …

The helmet he was wearing did not protect his neck; he was paralyzed from the neck down. …

”It didn’t cross my mind that this could happen,” said Philip, now 17.

”I definitely felt safe. I wouldn’t do something like that without a helmet.” ”

Safety experts recognise the role of risk compensation.
From the New York Times article:

”People tend to engage in risky behavior when they are protected,” he said. ”It’s a ubiquitous human trait.”

Even cyclists who discount the daredevil effect admit that they may ride faster on more dangerous streets when they are wearing their helmets.”

A study in Accident Analysis and Prevention found that children are also affected by risk compensation:

“Results indicated that children went more quickly and behaved more recklessly when wearing safety gear than when not wearing gear, providing evidence of risk compensation.”

A 1989 study found that helmet wearers were 7 times more likely to have accidents.

Risk compensation is an unconscious phenomenon.
We may not be aware of it.
Yet it affect the way we ride, the way we approach risks.

We are more likely to be hit by cars

Risk compensation also affects motorists.
Motorists tend to be less careful around helmeted cyclists. Drivers assume helmeted cyclists are “protected”.

A study published by the University of Bath in the UK reported that cars leave less room to helmeted cyclists:

“Bicyclists who wear protective helmets are more likely to be struck by passing vehicles”

Injuries tend to be more severe

Another subtle aspect of risk compensation is that we tend to ride faster.
A study in the Risk Analysis international journal found that:

“those who use helmets routinely perceive reduced risk when wearing a helmet, and compensate by cycling faster

In case of an accident, the higher speed results in more severe injuries.

There is a greater risk of the head hitting the road

In the event of an accident, helmets increase the risk of the head hitting the road.  Helmets increase the volume/size of contact area of the head. Helmeted riders are more than twice as likely to hit their head in an accident, with more impacts to the sides. Post-crash studies found that most helmets show impacts to the side,where a bare head is protected by the shoulders.

helmet-head-size-2Helmets increase the volume of the head, doubling chance of the head hitting the road in an accident;

A 1988 study reports that helmeted riders hit their heads seven times more often than un-helmeted riders.

We can suffer severe brain injury

In 1960, people believed that brain injury was due to linear acceleration, from the head hitting a wall for example. This belief has shaped the design of bicycle helmets.

Since, scientific research has shown that the main cause of brain injury is diffuse injury, caused by the head turning quickly. The skull may be intact, but there can severe internal brain injury. This article reports from a surgeon who operates on cyclists:

” “The ones with brain swelling, that’s diffuse axonal injury, and that’s bad news” …

the whole brain is shaken up, creating many little tears in its inner structure …

Such patients undergo personality change, can contract epilepsy and have difficulty controlling their anger. They might become unemployable. Depression is a common accompaniment to brain injury. Rosenfeld sees patients’ families shattered, too. “They’re never the same. It often leads to marriage disharmony and family breakdown.” …

Rosenfeld’s opinion is candid. “I don’t know if [helmets] do much to protect the inner part of the brain,” “

Research has found that helmets can increase rotational acceleration:

“The non-shell helmet did in all trials grab the asphalt surface, which rotated the head together with the helmet. The consequences were in addition to the rotating of the head, a heavily bent and compressed neck, transmitted on through the whole test dummy body after the impact.  …

This gives an average angular acceleration of 20800 rad/s² for rotating the head from 0 to 0.26 rad during the 5 ms. Löwenhielm proposes 4500 rad/s² to be the maximum angular acceleration that can be tolerated for a limited time period”

Helmets were found to amplify rotational acceleration to four times higher than the tolerable maximum.

The larger head volume amplifies rotational acceleration. A 3cm increase in helmet circumference increases rotational acceleration by 150%:

“the 3000rad/s² to 8500rad/s² measured during abrasive and projection oblique tests with size 54cm (E) helmeted headforms. However, for the most severe cases using a size 57cm (J) headform, rotational acceleration was typically greater than 10,000rad/s² and increased to levels of 20,000rad/s², a level at which a 35% – 50% risk of serious AIS3+ injuries is anticipated.”

The volume of a bicycle helmet amplifies rotational acceleration to dangerous levels where severe brain injury can occur.

A New Zealand doctor reports:

“cycle helmets were turning what would have been focal head injuries, perhaps with an associated skull fracture, into much more debilitating global head injuries”

In Canada, the length of stay in hospital increased increased following helmet laws, from 4.3 days to 6.9 days. The number of serious head injury admissions increased by 46%.

Contrary to popular belief, helmets are not designed to protect against brain injury.
However, they can increase rotational acceleration, causing severe brain injury.

What a load of rubbish!

This might sound like a load of rubbish to cyclists who wear helmets. Some believe their helmet saved their life. Few consider they may have fewer accidents without a helmet.

Cycling injuries rose dramatically after a helmet law was introduced in Australia.

cycling_injury_rateThe rate of cycling injuries tripled after Australia introduced a helmet law.

You might feel safer wearing a helmet.
However that doesn’t mean you are safer.

What do you think of this post?
  • Insightful (17)
  • Interesting (14)
  • Useful (5)
  • Boring (4)

The myth that bicycle helmets protect against brain injury

Abstract

Brain injury is caused by rotational acceleration.
Bicycle helmets are not designed to protect against it.
In some circumstances they can increase it, aggravating brain injury.
Wearing a helmet can make us feel safer. However feeling safe is different than being safe

blank

What surgeons say

This article reports from a surgeon who operates on cyclists:

“The ones with brain swelling, that’s diffuse axonal injury, and that’s bad news” …

the whole brain is shaken up, creating many little tears in its inner structure …

Such patients undergo personality change, can contract epilepsy and have difficulty controlling their anger. They might become unemployable. Depression is a common accompaniment to brain injury. Rosenfeld sees patients’ families shattered, too. “They’re never the same. It often leads to marriage disharmony and family breakdown.” …

Rosenfeld’s opinion is candid.  “I don’t know if [helmets] do much to protect the inner part of the brain,”

A neurosurgeon from the UK admits:

“I see lots of people in bike accidents and these flimsy little helmets don’t help.”

According to another Australian surgeon who operates on cyclists:

“The best evidence is that [a helmet] doesn’t make any difference to serious head injury when riding a bicycle …

initial research used to back the mandatory laws was “deeply flawed and criticised”. Some newer findings, he said, showed that these laws could increase the chance of serious injury. “

Sport cyclists are having doubts

Helmets are part of the sport cyclist uniform. Yet fatalities have doubled since mandatory helmets:

The helmet rule for professional cyclists was brought by the UCI in 2003 following the death of Andrei Kivlev during the Paris-Nice race.

Since then deaths of professional cyclists while racing have doubled, so where is the protection that helmets are supposed to give a rider?

Sport cyclists are having doubts, as reflected in a recent edition of Bicycling Magazine:

new research is finding that concussions could be as dangerous as splitting open your skull. And that brain bucket you own? It was never designed to prevent concussions.

Distinguishing between focal brain injury and diffuse brain injury

What’s going on? Why do people believe that bicycle helmets protect against brain injury while surgeons say they don’t? Much of the confusion comes from a lack of distinction between focal brain injury and diffuse brain injury.

An old popular belief is that brain injury is caused by a direct hit the head, like a head hitting a wall, causing linear acceleration. This is focal brain injury. Bicycle helmets are designed to reduce focal injury. The polystyrene reduces linear acceleration by compressing on impact.

Scientific research done in the 1970’s has revealed that the main cause of severe brain injury is not focal injury but diffuse axonal injury:

“The experiments gave special attention to direct comparison of the contributions of linear and angular acceleration because the widely accepted Head Injury Criterion for head injury is based on measurements of the former – see below. The essential role of angular acceleration in producing cerebral concussion was shown, the threshold being estimated as 2000-3000 rad/sec². Translation was also responsible for brain injuries, albeit only focal, and did not produce concussion.  …

Along with the support which research has provided for the new theory, it has discredited the notions of coup and contre-coup and of linear acceleration of the brain being a major factor in injury to it.”

Diffuse axonal injury, also called rotational injury, is caused by angular acceleration, for example when the head rotates quickly. The skull may be intact, but there can be severe internal brain damage. This is what the surgeon Dr.  Rosenfield was describing in the article mentioned above.

Some people believe helmets protect against brain injury. Not only is this not true, but the opposite is more likely to be the case:

“Protecting the brain from injury that results in death or chronic disablement provides the main motivation for wearing helmets. Their design has been driven by the development of synthetic polystyrene foams which can reduce the linear acceleration resulting from direct impact to the head, but scientific research shows that angular acceleration from oblique impulse is a more important cause of brain injury. Helmets are not tested for capacity to reduce it and, as Australian research first showed, they may increase it.

Even though helmets do not protect against brain injury, fear of chronic disability has been used to promote them. This has lead to an exaggerated opinion of the protection provided by helmets. A false sense of safety can lead to increase risk taking, as reported in the New York Times:

“the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks. …

The helmet he was wearing did not protect his neck; he was paralyzed from the neck down. …

I definitely felt safe. I wouldn’t do something like that without a helmet.” 

Research on bicycle helmets

Soft-shell helmets, the most common type of bicycle helmet, are helmets without a hard shell. They have a thin layer of plastic on top, less than 1 mm.

 A soft-shell helmet is a piece of polystyrene covered by a layer of plastic less than 1mm thick.

In 1987, an Australian government agency released research that highlighted deficiencies with bicycle helmets:

The substantial elastic deformation of the child head that can occur during impact can result in quite extensive diffuse brain damage. It is quite apparent that the liner material in children’s bicycle helmets is far too stiff …

rotational accelerations were found to be 30% higher than those found in similar tests using a full face polymer motorcycle helmet. More work needs to be done in this area as there would seem to be a deficiency in rotational acceleration attenuation that may be the result of insufficient shell stiffness

Helmets can increase brain injury, according to research done in Sweden:

“The non-shell helmet did in all trials grab the asphalt surface, which rotated the head together with
the helmet. The consequences were in addition to the rotating of the head, a heavily bent and compressed neck, transmitted on through the whole test dummy body after the impact.  …

This gives an average angular acceleration of 20800 rad/s² for rotating the head from 0 to 0.26 rad during the 5 ms. Löwenhielm proposes 4500 rad/s² to be the maximum angular acceleration that can be tolerated for a limited time period”

Soft-shell helmets amplified rotational acceleration to four times higher than the tolerable maximum.

On impact, the larger head volume amplifies rotational acceleration. 3cm increase in helmet circumference increases rotational acceleration by 150%:

“the 3000rad/s² to 8500rad/s² measured during abrasive and projection oblique tests with size 54cm (E) helmeted headforms. However, for the most severe cases using a size 57cm (J) headform, rotational acceleration was typically greater than 10,000rad/s² and increased to levels of 20,000rad/s², a level at which a 35% – 50% risk of serious AIS3+ injuries is anticipated.”

The difference between a helmeted and non-helmeted head is about 20cm.

The mechanics of bicycle helmets

Look at a bicycle helmet. It has been designed with comfort in mind. It is made of light weight material that grip the road on impact rather than glance off it (as is the case with motorcycle helmets).

Helmets increase the volume of the head. In the event of an accident, this increases the risk of the head hitting the road.

The increase in the volume of the head, coupled with the gripping of the road surface, means that when a head comes into contact with the ground at speed, the head or body is rotated, sometimes snapping the spinal cord. This can cause brain injury or permanent disability.

Post-crash studies found that most helmets show impacts to the side, where a bare head is protected by the shoulders.

 

Helmets increase volume of the head, increasing the chance of the head hitting the road in an accident.
The larger volume amplifies rotational acceleration, the main cause of brain injury.
blank

Is this just a theory?

Unfortunately it doesn’t seem like it.

doctor from New Zealand reports:

“cycle helmets were turning what would have been focal head injuries, perhaps with an associated skull fracture, into much more debilitating global head injuries”

In Canada, the length of stay in hospital increased increased following helmet laws, from 4.3 days to 6.9 days. The number of serious head injury admissions increased by 46%.

Helmeted riders are more than twice as likely to hit their head in an accident, with more impacts to the sides. A 1988 study reports that helmeted riders hit their heads seven times more often than un-helmeted riders.

In the US, a strong rise in helmet wearing was followed by an increase in head injuries:

“Bicycle helmets might not protect cyclists much at all.  And, in fact, in some cases, they might actually be more dangerous than going lidless. …

head injuries had increased even though the use of helmets had skyrocketed throughout the 1990s.  The risk of injury per cyclist had gone up by 51%. …

We don’t know what’s going on,” said one political appointee who should know.  Well, I’ll offer my idea.  People accepted the idea that helmets work, and then created studies to “prove” that they do. “

It is easy to take things for granted, and to assume that a device labeled a “helmet” can only protect, and cannot make things worse.

What about the studies that claim that helmets protect against 80% of brain injuries?

There have been many “studies” claiming that helmets protect against brain injuries. The most famous one was done by helmet lobbyists and funded by the helmet industry. This “study” had methodological errors. It was the basis for a US government claim that helmets reduce 85% of head injuries. The US government has since dropped this claim.

Many studies assume that helmets are effective and attempt to “prove” it. Such studies jump to a predetermined conclusion, with a disturbing lack of scientific discipline. Often the claims are contradicted by the study’s own data.

Governments who enacted helmet law have funded policy-driven studies defending their policy. Such “studies” use biased statistics, resulting misleading claims. Bill Curnow, a scientist from the CSIRO, wrote as a conclusion of a scientific article:

“Compulsion to wear a bicycle helmet is detrimental to public health in Australia but, to maintain the status quo, authorities have obfuscated evidence that shows this.”

In 2011, the New South Wales government funded a study trying to deny that helmets can aggravate brain injury. This risk exists for soft-shell helmets at high speed. The “study” set up unrealistic conditions at low speed, then magically generalized the results. This is deceitful as the unrealistic conditions are not representative of real life accidents.

The dilemma: minor skull injuries vs brain injury

Bicycle helmets are designed to protect cyclists if they fall on top of their heads at speeds below 20 km/h. They mitigate against minor skull injuries like bruises and lacerations. They are not tested for side impacts.

Is it worth to increase the risk of brain injury to mitigate minor skull injuries? An Australian cyclist challenged a helmet fine as helmets can increase brain injury. After reviewing evidence in a court of law, District Court Judge Roy Ellis concluded:

“”Having read all the material, I think I would fall down on your side of the ledger …

I frankly don’t think there is anything advantageous and there may well be a disadvantage in situations to have a helmet  and it seems to me that it’s one of those areas where it ought to be a matter of choice.”

What do you think of this post?
  • Insightful (4)
  • Interesting (1)
  • Useful (1)
  • Boring (1)

The paradox of bicycle helmets

Abstract

In a scenario where the very act of wearing “protection” ironically leads to a surge in injuries, it becomes imperative to dig deeper and unravel the underlying issues.

Adorning a bicycle helmet certainly instills a sense of safety and protection. However, it’s essential to recognize that this perception of invincibility can inadvertently lead us and those around us to engage in riskier behaviors. This, in turn, significantly elevates the likelihood of accidents and injuries.

It’s vital to acknowledge the subtle distinction between feeling safe and actually being safe. While donning a helmet might provide a sense of security, this perception can lead us astray when the stark reality reveals a heightened risk of harm. 

_____

After a helmet law was introduced in Australia, many cyclists insisted their helmets had saved them.

Yet cycling injuries increased.

How can both be true at the same time?

They can be true at the same time if there is a large increase in accidents.

From the injury data, this is what happened.

This is the paradox of bicycle helmets. People believe their helmets saved them, despite suffering more injuries. The irony is that the helmet saved them from accidents that may not have happened without the helmet.

It seems “obvious” & “intuitive” that wearing a helmet should reduce injuries.
Yet sometimes our intuition can be wrong.
Sometimes there are consequences we cannot see that are more harmful than what seems obvious.

More helmets –> more accidents –> more injuries

This surprising result not unique to Australia. Other countries have experienced increased injuries following an increase in helmet wearing.

In the US, a rise in helmet wearing led to more head injuries, according to the New York Times

the rate of head injuries per active cyclist has increased 51 percent just as bicycle helmets have become widespread…

the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks…

”People tend to engage in risky behavior when they are protected,” he said. ”It’s a ubiquitous human trait.”

Even cyclists who discount the daredevil effect admit that they may ride faster on more dangerous streets when they are wearing their helmets.

In New Zealand, a study found that injuries more than doubled following a bicycle helmet law.

1989 US study found that helmet wearers were 7 times more likely to have accidents.
How can a flimsy piece of polystyrene compensate for 7 times more accidents?

A strange helmet culture

Riding in Australia is a unique experience. Cycling accidents are considered normal. There is a special word for a bicycle accident, called a “stack”. Many cyclists have tales of their frequent “stacks”, and how each stack reinforce their belief in helmets. They would never ride without a helmet. Cycling is far too dangerous, even suicidal, according to a doctor from Melbourne:

riding a bicycle on Melbourne’s roads … is “verging on suicide”

It is a strange ideology, where helmets and accidents justify each other.
Cyclists wear helmets because they have frequent accidents.
Wearing a helmet increases the risk of accidents.

Contrast this with countries that do not mandate helmets, like the Netherlands.
Accidents are rare.
Cyclists have little fear of accidents.
Cycling is safe.

Which philosophy is safer?

  1. Accident avoidance: no helmets, few accidents. The Netherlands
  2. Accident protection: many accidents protected by helmets. Australia.

Australia cycling serious injury rate is 22 times greater than in the Netherlands:

Can bicycle helmets compensate for more accidents?

Choosing to wear a helmet seems a like “No brainer“. Such an obvious “precaution”.

Choosing not to wear a helmet is a more subtle decision.
It requires paying attention to what cannot easily been seen, rather than what seems “obvious”.
It requires an understanding of how helmets affect the risk of accidents.
It requires comparing a higher risk of accident with protection from polystyrene. 

It feels safer to wear a helmet. Yet the evidence indicates it may not be safer.

The paradox is: feeling safe is not the same as being safe.

What do you think of this post?
  • Insightful (2)
  • Interesting (0)
  • Useful (0)
  • Boring (0)

Are bicycle helmets dangerous?

Abstract

 blank

 

Helmets protect against minor skull injuries like bruises and lacerations.

Helmets:

  1. increase the risk of accidents
  2. increase the risk of neck injury
  3. increase the risk of brain injury
Wearing a helmet can make us feel safer.
However feeling safe is not the same as being safe

 

Some politicians claim “Helmets save lives“.

Is this true? CRAG has asked for evidence, but the government has been unable to provide any.

Even helmet salespeople do not make such claims. After being asked

Can your helmet save your life?“,

a helmet salesperson shrugged and laughed uncomfortably, before responding

Can it?” “Well, not save your life, no.

What is it that politicians know that helmet salespeople don’t?

What protection do helmets provide?

A bicycle helmet is a piece of polystyrene covered by a layer of plastic less than 1mm thick.
It can protect in a minor accident.  However, it is not designed to protect in a serious accident.

Bicycle helmets are a piece of styrofoam designed to protect in minor impacts:

“In cases of high impact, such as most crashes that involve a motor vehicle, the initial forces absorbed by a cycle helmet before breaking are only a small part of the total force and the protection provided by a helmet is likely to be minimal in this context. In cases where serious injury is likely, the impact energy potentials are commonly of a level that would overwhelm even Grand Prix motor racing helmets. Cycle helmets provide best protection in situations involving simple, low-speed falls with no other party involved. They are unlikely to offer adequate protection in life-threatening situations.“

In serious accidents, they tend to disintegrate on impact, absorbing little energy. This crumbling is what many people mistake the helmet for as having saved their life:

“The next time you see a broken helmet, suspend belief and do the most basic check – disregard the breakages and look to see if what’s left of the styrofoam has compressed. If it hasn’t, you can be reasonably sure that it hasn’t saved anyone’s life.“

Dr Carwyn Hooper from St George’s University in London reports:

“Looking at evidence, it does not matter if people are wearing a helmet or not, any serious accident on a bike is likely to kill them,”

Bicycle helmets protect against bruises and minor lacerations.
Yet, cycling injuries tripled after Australia introduced a helmet law.

The rate of cycling injuries tripled after Australia introduced a helmet law.

How can the widespread wearing of helmets increase the risk of injuries?

Although helmets protect, they can also increase the risk of accidents.

Increase risk of accidents

A false sense of safety can induce people to take more risks, leading to more accidents and more injuries. This is risk compensation, a well-known safety factor:

“the law of unintended consequences is extraordinarily applicable when talking about safety innovations. Sometimes things intended to make us safer may not make any improvement at all to our overall safety”

Risk compensation is the tendency to take more risks when wearing safety equipment.

Wearing a helmet can induce cyclists to take more risks. This can lead to permanent disability, as reported in the New York Times:

the rate of head injuries per active cyclist has increased 51 percent just as bicycle helmets have become widespread. …

the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks. …

The helmet he was wearing did not protect his neck; he was paralyzed from the neck down. …

”It didn’t cross my mind that this could happen,” said Philip, now 17.
”I definitely felt safe. I wouldn’t do something like that without a helmet.” ”

Safety experts recognise the role of risk compensation. From the New York Times article:

”People tend to engage in risky behavior when they are protected,” he said. ”It’s a ubiquitous human trait.”

Even cyclists who discount the daredevil effect admit that they may ride faster on more dangerous streets when they are wearing their helmets.

1989 study found that helmet wearers were 7 times more likely to have accidents.

Risk compensation also affects motorists who tend to be less careful around helmeted cyclists. As reported in a study published by the University of Bath in the UK:

“Bicyclists who wear protective helmets are more likely to be struck by passing vehicles”

Children are affected by risk compensation, as reported in Accident Analysis and Prevention :

“Results indicated that children went more quickly and behaved more recklessly when wearing safety gear than when not wearing gear, providing evidence of risk compensation.”

Helmets encourage people to ride faster, as reported by the Risk Analysis international journal:

“those who use helmets routinely perceive reduced risk when wearing a helmet, and compensate by cycling faster

The severity of injuries is much higher at higher speeds.

Many people believe that helmets protect against brain injury. Do they?

What causes brain injury?

In 1960, people believed that brain injury was due to linear acceleration, from the head hitting a wall for example. This belief has shaped the design of bicycle helmets.

Since, scientific research has shown that the main cause of brain injury is diffuse injury, caused by the head turning quickly. The skull may be intact, but there can severe internal brain injury. This article reports from a surgeon who operates on cyclists:

” “The ones with brain swelling, that’s diffuse axonal injury, and that’s bad news” …

the whole brain is shaken up, creating many little tears in its inner structure …

Such patients undergo personality change, can contract epilepsy and have difficulty controlling their anger. They might become unemployable. Depression is a common accompaniment to brain injury. Rosenfeld sees patients’ families shattered, too. “They’re never the same. It often leads to marriage disharmony and family breakdown.” …

Rosenfeld’s opinion is candid. “I don’t know if [helmets] do much to protect the inner part of the brain,” “

Helmets can increase brain injury, according to this research:

“The non-shell helmet did in all trials grab the asphalt surface, which rotated the head together with
the helmet. The consequences were in addition to the rotating of the head, a heavily bent and compressed neck, transmitted on through the whole test dummy body after the impact.  …

This gives an average angular acceleration of 20800 rad/s² for rotating the head from 0 to 0.26 rad during the 5 ms. Löwenhielm proposes 4500 rad/s² to be the maximum angular acceleration that can be tolerated for a limited time period”

Helmets amplified rotational acceleration to four times higher than the tolerable maximum.

On impact, the larger head volume amplifies rotational acceleration. A 3cm increase in helmet circumference increases rotational acceleration by 150%:

“the 3000rad/s² to 8500rad/s² measured during abrasive and projection oblique tests with size 54cm (E) helmeted headforms. However, for the most severe cases using a size 57cm (J) headform, rotational acceleration was typically greater than 10,000rad/s² and increased to levels of 20,000rad/s², a level at which a 35% – 50% risk of serious AIS3+ injuries is anticipated.”

The difference between a helmeted and non-helmeted head is about 20cm.

Increase risk of the head hitting the road

In the event of an accident, helmets increase the risk of the head hitting the road.  Helmets increase the volume/size of contact area of the head. Helmeted riders are more than twice as likely to hit their head in an accident, with more impacts to the sides. Post-crash studies found that most helmets show impacts to the side,where a bare head is protected by the shoulders.

 

Helmets increase volume of the head, doubling chance of the head hitting the road in an accident;
The larger volume also amplifies rotational acceleration, the main cause of brain injury.
blank

A 1988 study reports that helmeted riders hit their heads seven times more often than un-helmeted riders.

Helmets are not suitable for children’s more deformable head

In 1987, the Federal Office of Road Safety published research on helmets. This research highlighted serious deficiencies with bicycle helmets:

The substantial elastic deformation of the child head that can occur during impact can result in quite extensive diffuse brain damage. It is quite apparent that the liner material in children’s bicycle helmets is far too stiff …

rotational accelerations were found to be 30% higher than those found in similar tests using a full face polymer motorcycle helmet. More work needs to be done in this area as there would seem to be a deficiency in rotational acceleration attenuation that may be the result of insufficient shell stiffness. 

 

Bicycle helmets helmets are designed for adult heads. They are too stiff for children more deformable heads. Despite this, helmets are promoted as “protecting” children, without appropriate warnings.

Helmets are associated with more severe brain injuries

New Zealand doctor reports:

“cycle helmets were turning what would have been focal head injuries, perhaps with an associated skull fracture, into much more debilitating global head injuries”

In Canada, the length of stay in hospital increased increased following helmet laws, from 4.3 days to 6.9 days. The number of serious head injury admissions increased by 46%.

Do helmets provide a net safety benefit?

Bicycle helmets are a safety trade-off. They protect the skull against bruises and lacerations. But they increase the risk of accidents and can increase brain injury.

Evidence provided in court suggests that helmets provide limited protection.:

“So in at least one case now, a High Court has decided that the balance of probability was, in the matter before the Court, that a cycle helmet would not have prevented the injuries sustained when the accident involved simply falling from a cycle onto a flat surface, with barely any forward momentum. …

the QC … repeatedly tried to persuade the neurosurgeons … to state that one must be more safe wearing a helmet than would be the case if one were not. All three refused to do so, claiming that they had seen severe brain damage and fatal injury both with and without cycle helmets

recent meta-analysis of helmets effectiveness reports reports no net beneficial effect. They do not protect against facial injuries, and increase neck injuries.

The belief that helmets can only improve safety may be a myth:

“Bicycle helmets might not protect cyclists much at all.  And, in fact, in some cases, they might actually be more dangerous than going lidless. …

head injuries had increased even though the use of helmets had skyrocketed throughout the 1990s.  The risk of injury per cyclist had gone up by 51%. …

We don’t know what’s going on,” said one political appointee who should know.  Well, I’ll offer my idea.  People accepted the idea that helmets work, and then created studies to “prove” that they do. “

We do not know whether helmets provide a net safety benefit. We do know that injuries have increased after a helmet law was imposed in Australia. The risk of death & serious injury increased by 50% for child cyclists. 

The UK’s National Children’s Bureau provided a detailed review of cycling and helmets in 2005:

“The conclusion from the arguments outlined above is that the case for cycle helmets is far from, sound. The strong claims of injury reduction made by helmet proponents have not been borne out for fatalities (which this paper argues is the most methodologically sound test of effectiveness) in real-life settings with large populations. …

the benefits of helmets need further investigation before even a policy supporting promotion can be unequivocally supported. ….

The cycle helmet debate shows the dramatic power of real life events in shaping our understanding of causality. Tragedies happen; child cyclists are killed or left disabled for life; and we cannot let go of the belief that something 
could and should have been done to stop that particular event from happening – especially when that something is so simple as wearing a helmet. We find it hard to accept that the helmet may have made no difference. We find it harder to accept that encouraging or forcing children to wear helmets might also encourage them to ride in a more dangerous way and paradoxically to increase the risk that they will suffer an accident. And we find it much harder to accept that compulsory helmet use might put children off cycling altogether, leaving them less physically active, and – many years later – more likely to die of heart disease.Think of all the uncertainty behind that line of argument, compared with the seeming rock-solid conviction that a helmet could have saved that particular child’s life, at that particular time. And of course the fact that we are talking about children, who have a claim on our protection and who are still getting to grips with the world, makes it so much more difficult to accept the limitations on our ability to prevent them coming to harm. We cannot ignore the human suffering, pain and loss that lie behind the research and statistics. But our response to it demands reflection and perspective as well as sympathy and conviction.

Is it worth to increase the risk of brain injury to mitigate minor skull injuries? An Australian cyclist challenged a helmet fine as helmets can increase brain injury. After reviewing evidence in a court of law, NSW District Court Judge Roy Ellis concluded:

“”Having read all the material, I think I would fall down on your side of the ledger …

I frankly don’t think there is anything advantageous and there may well be a disadvantage in situations to have a helmet  and it seems to me that it’s one of those areas where it ought to be a matter of choice.

What about the studies that claim that helmets protect against 80% of head injuries?

There have been many “studies” claiming that helmets protect against brain injuries. The most famous one was done by helmet lobbyists and funded by the helmet industry. This “study” had methodological errors. It was the basis for a US government claim that helmets reduce 85% of head injuries. The US government has since dropped this claim.

Many studies assume that helmets are effective and attempt to “prove” it. Such studies jump to a predetermined conclusion, with a disturbing lack of scientific discipline. Often the claims are contradicted by the study’s own data.

Governments who enacted helmet law have funded policy-driven studies defending their policy. Such “studies” use biased statistics, resulting in misleading claims. Bill Curnow, a scientist from the CSIRO, wrote as a conclusion of a scientific article:

“Compulsion to wear a bicycle helmet is detrimental to public health in Australia but, to maintain the status quo, authorities have obfuscated evidence that shows this.”

In 2000, a government agency published a meta-analysis, that claimed to provide

overwhelming evidence in support of helmets for preventing head injury and fatal injury“.

This study was re-assessed by an independent researcher who concluded:

This paper … was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycle helmets …

According to the new studies, no overall effect of bicycle helmets could be found when injuries to head, face or neck are considered as a whole

After attempts to justify its policy through misleading “studies”, and following CRAG submission to the Prime Minister in 2009, the federal government abandoned its compulsory helmets policy.

What do you think of this post?
  • Insightful (2)
  • Useful (2)
  • Interesting (0)
  • Boring (0)

Confusing helmets with polystyrene hats

Why are these two devices given the same name?

Motorcycle HelmetThis device protects in a serious accident

helmet-soft-shell-2This device crumbles in a serious accident

Imagine a drug manufacturer introduces a new medicine it calls new aspirin. Yet the new aspirin is only 1% as effective as current aspirin. There would be an outcry. It is misleading to give the same name to a product that isn’t as effective. The drug manufacturer would have to use a different name to avoid misleading consumers.

Yet, in the 1980s, helmet manufacturers marketed “bicycle helmets”. They were essentially a piece of polystyrene. They provided much less protection than existing helmets. Yet the manufacturers got away with the misleading label.

soft-shell-helmetMost “bicycle helmets” are actually a piece of polystyrene covered by a thin layer of plastic

Why do they have the same name?

There are two powerful vested interests benefiting from the confusion:

  1. Helmet manufacturers. Labelling a polystyrene hat a “helmet” suggests it provides significant protection. It becomes a safety device. A polystyrene hat couldn’t sell for much more than $10. A helmet can sell for $100.
    There are huge profits in selling bicycle helmets. In the late 1980’s, bicycle helmets were the most profitable of all types of helmets. Helmet manufacturer were keen to expand this market. They used their profit bonanza to increase market size. They commissioned “studies” claiming that bicycle helmets protect against brain injury. They lobbied governments for a helmet law. Their efforts lead to the introduction of a bicycle helmet law in Australia.
  2. Politicians like to be seen “doing something” to improve safety. In Europe, cycling safety has improved by protecting cyclists from motorised traffic. This reduces accidents, but requires effort and investment. In countries where there are few votes in cycling, politicians can take shortcuts. They can pretend that polystyrene hats make cycling “safe”. Imposing a mandatory bicycle helmet law sounds like a plausible policy.
    If the policy was called “mandatory polystyrene hat”, it would be obvious it is a fake safety measure.

Effective politicians master the art of peddling what seems plausible. Policies don’t have to work to attract votes. They only need to be plausible to appeal to enough voters.

Language affects our perception. We can be tricked by mis-labelling an issue. For example labelling a problem an “opportunity” makes it feel less painful. Labelling a polystyrene hat a “helmet” makes it seem like a safety device.

Why isn’t there any oversight?

Unlike medicine, road safety suffers from poor oversight. Companies can market products with misleading names.

“Road safety” bureaucrats are mostly unaccountable. They can produce policies that do more harm than good. There is no independent auditor that checks the policies effectiveness. In medicine, drugs have to go through diligent trials. They look for side effects, ensuring the drugs does no harm. Road safety policy lacks such safeguards.

Policies that do more harm than good can be sustained for years. Bureaucrats can throw plenty of taxpayers money to defend their policies:

  1. “Road safety” advertising. This often uses fear mongering to scare people. When we are afraid, we seek safety. This is what the policy promises. The advertising finds an emotional way to associate the government policy with “being safe”. It doesn’t to have be true. It only has to be plausible. With enough emotional manipulation, any plausible policy can build up popular support.
  2. Commissioning “studies” to defend the policy. A bureaucrat offers generous funding to conduct a “study” related to a government policy. If the study concludes the policy is ineffective, the academic is unlikely to get further funding. Most studies conclude that the policy is beneficial.
    Most of these studies lack scientific discipline. A meta-analysis of drunk driving prevention and control literature from 1960 through 1991 identified 6500 documents, of which only 125 passed minimal standards of scientific rigor and qualityLess than 0.2% of the “studies” passed minimal scientific standards!  Lacking scientific discipline, studies make invalid claims defending the policy. This is junk science. It misuses science for political purposes.
    These “studies” are used to denigrate critics who point out the policy ineffectiveness. They are an obfuscation tool.

Using such tricks, policies that do more harm than good can remain in place for years. This keeps the bureaucrats in their cushy jobs, while the politicians get the votes. The bureaucrats and politicians do not suffer from the consequences of their mistakes. We do. This could not happen with independent oversight.

If it’s a duck, call it a duck!

Vested interests benefit from the confusion between helmets and polystyrene hats.

Yet, the public does not benefit from being mislead.
What we can do to reduce the confusion is to insist on a name that does not mislead.
When it’s a duck, call it a duck.
When it’s a polystyrene hat, call it a polystyrene hat.

What do you think of this post?
  • Insightful (8)
  • Interesting (7)
  • Useful (6)
  • Boring (5)