Playground Surfacing Requirements and Injury Reduction

It is somewhat of a delicate balancing act between providing enough safety requirements to keep children from being seriously harmed while not tipping the scale away from our ability to provide more challenging risky play opportunities. In reviewing the scoping statements of various international playground equipment and surfacing standards, it appears this line is blurred. How much regulation is needed to meet the needs of children as they seek the thrill of challenge versus the unintended consequences when their developmental abilities are inadequate to assess their risk of harm? What level of consequence (severity of injury) is a fair trade-off for the developmental benefits of risky challenging play opportunities?

Falls to Surface - Number one cause of injury and one of four top causes of death on playgrounds

We have known since the early 1970s the number one cause of serious playground injuries requiring medical attention is falls to the surface. What frequency and severity of fall-related injuries can we live with? Most of these fall injuries result in long bone fractures, which occur far more frequently than a serious head injury. Which injury is more severe? It depends on the level of severity, which is determined by trained medical professionals using the Abbreviated Injury Scale (AIS) rating system.

The causes of these fall-related injuries are many. Sometimes the child lacks the physical and cognitive abilities necessary to successfully use the equipment as intended or the child decides to use the equipment in unintended ways. The equipment may have had some design issues or it was not properly installed. Often the owner/operator does not maintain the equipment or surfacing in accordance with the manufacturer’s instructions, and the equipment breaks or the surfacing no longer provides the minimum protection required by the standards.

What about those serious injuries that occur on playgrounds that are well maintained within the minimum requirements of the standards? Should injuries occurring on playgrounds meeting or exceeding standards’ requirements be accepted as a part of everyday life, or should there be some change in our approach to the cause and effect of falls on the playground surface?

The effort to reduce the current impact attenuation thresholds set by ASTM International (ASTM) F1292 (Standard Specification for Impact Attenuation of Surfacing Materials within the Use Zone of Playground Equipment) has been going on for a long time. Parties on both sides of the issue have done their best to bring the most current information to the attention of the F08.63 (Playground Surfacing Systems) Subcommittee members.

A look at the recent vote to change from 1000 HIC to 700 HIC

Before getting into the real issue of surfacing performance and injury reduction, let’s address a little issue related to accusations made against the ASTM International organization and its members. ASTM and the ASTM F08.63 Subcommittee are due an apology for some of the comments that have been made and/or implied on how the ASTM and their volunteer members conduct the business of developing voluntary industry standards.

The following statement was written by one of the interested parties against the threshold reduction to 700 HIC (Head Injury Criterion), and is true, to some extent. 

“This is a complex issue with strongly-held views. I will continue to foster reasoned, constructive debate and share news and views, here and elsewhere, to the best of my ability – though there are challenges, not least the lack of transparency in ASTM’s decision-making. To repeat: there is no doubt that the extent of debate and opposition to ASTM’s proposal has helped to get this result.”

Determining what is the appropriate impact attenuation threshold is a complex issue, but to imply the ASTM process is underhanded and non-transparent or flawed could not be further from the truth. The question still remains whether the outcome of the last ballot and the successful appeal was the correct result. Let’s start with some background information to the issue at hand.

Here are the facts on the ASTM Process

There are many Committees within the ASTM organization. There are 36 Subcommittees within the F08 (Sports Equipment, Playing Surfaces, and Facilities) Committee. The F08.63 Subcommittee is responsible for all playground-related surfacing standards and guides. This Subcommittee currently has about 160 voting members. Once a Subcommittee ballot item has gone through the Subcommittee approval process, it must then be upheld by the Main Committee ballot. The point is there are many opportunities for the dissenting opinions on any issue to have their negative vote and rationale heard.

"ASTM and the ASTM F08.63 Subcommittee are due an apology for some of the comments that have been made..."

In this instance, the ASTM International voting process was followed. A 90% affirmative vote is required to continue to move the ballot issue forward to the next step in the approval process. The results in this first ballot were overwhelmingly in favor of the change (> 9 to 1). The next step in the voting process is to address any negative votes. The few negative votes received were then reviewed by the task group. Written rationale was provided to find the negative votes non-persuasive. The rationale for finding the negatives non-persuasive was put in the form of a motion and a ballot was voted on by the entire F08 Main Committee. The results of this ballot were again overwhelmingly in favor of the change (> 8 to 1) to reduce the HIC to 700. This step requires a super majority (> 2/3rds) affirmative vote. All ballots are then approved by the ASTM Committee on Standards (COS) before they can get published.

An appeal was made to the ASTM Committee on Standards. The appeal findings had nothing to do with the merits of the change to the HIC. The issue was whether or not the Subcommittee properly handled the negative vote process. The primary issue had to do with the timeline in which supplemental information related to the ballot item was sent to the Chair and distributed electronically to all F08.63 Subcommittee members. This information was believed, by some, to support those members who voted in opposition to the proposed HIC reduction. Distribution of these materials occurred after the ballot was posted for the vote to find the negative voters’ rationale non-persuasive. By the time the documents were distributed, some ASTM members had cast their vote. Regardless of the timeline issue, the documents were sent to everyone and the voting deadline was extended. Anyone who wished to change their vote was allowed to do so. The voting results were as stated above.

If these voting results had been upheld by the COS, the reduction of the HIC from 1000 to 700 would have occurred. The COS heard and upheld the appeal based on the timeline for how this new information was handled in relationship to the ballot posting and closing dates. COS thought there should have been more time allowed prior to the ballot closing date or the ballot should have been delayed. The COS ruling on this appeal required this ballot item go out to a vote once again. 

Did new documents in question support no change to the 1000 HIC?

So you might ask, what was so compelling about this new information in support of the status quo of 1000 HIC? Prior to the appeal hearing and action by the ASTM COS, the information in question was presented and discussed at the ASTM F08.63 Subcommittee meeting. I was at that meeting. It was a very lively discussion. These papers were determined to be of no consequence to the matter being balloted as they did not support either lowering or leaving the HIC at 1000. 

Some of the so-called supporting documents were National Electronic Injury Surveillance System (NEISS) findings on fall injury reports and serious head injury reports from 2001-2008. What these reports do not represent is the real number of fall-related injuries and how many of these falls resulted in serious head injuries. NEISS report analysis is a statistical sampling of a small number of pre-selected hospitals that would be representative of the demographic distribution of all Americans. So NEISS numbers are a statistical projection of injuries based on the information gathered by the NEISS participating member hospitals. The information gathered from these reported fall injuries does not give enough detailed information about the accident to assist in this surface performance debate. Some just state, “person fell to surface.” Nothing is known about the characteristics of the surface or if it was compliant. The report states the person was transported to the hospital by ambulance, treated, and released. It is not known the extent of the injury or if there was any negative impact to the injured party after that initial treatment. Very few people stay in hospitals overnight if they can be observed, cared for, and treated at home. Are these injuries serious or not? Can anyone determine how many serious head injuries are too many? Is a number really necessary? There seem to be more questions than answers. 

"The study’s conclusion that 12 compressed inches of this sand is superior to 12 compressed inches of wood chips raises some additional questions about surfacing recommendation in the U.S. Consumer Product Safety Commission’s Public Playground Safety Handbook..."

The other research document was a research paper titled, School Playground Surfacing and Arm Fractures in Children: A Cluster Randomized Trial Comparing Sand to Wood Chip Surfaces (Howard, 2009). This study was based on the Toronto Public School’s experience with injury reduction. This study appeared to have too many unanswered questions to provide concrete evidence that the 1000 HIC was adequate or that the benefits of a reduction to 700 HIC were measurable and substantial enough to be worth the cost.

Two Points of View - What can we learn from the Howard Study? 

Since the initial discussion on the Howard Study and after the COS appeal decision, there were two presentations made by Subcommittee members at the following May ASTM meeting in Anaheim, California. These presentations were based on the findings of the Howard Study. This research paper was about injury reduction in Toronto Public Schools. The focus was on which of two types of loose-fill surfacing material was most effective in injury reduction, primarily fractures: wood chips or granitic sand. The study concluded a higher reduction in fractures on this special granitic sand than with wood chips.

The study’s conclusion that 12 compressed inches of this sand is superior to 12 compressed inches of wood chips raises some additional questions about surfacing recommendation in the U.S. Consumer Product Safety Commission’s Public Playground Safety Handbook, since it still shows a 4 foot critical height for 9 inches of compacted sand. This study proves that not all sand is the same or performs equally. While depth of surface material can have an effect on performance, there is no guarantee that more depth will result in better impact-attenuating results.

What the study does not discuss are the changes the school district made to their playground design guidelines prior to the study. Before the study and new school guidelines there were many very tall wooden structures that did not conform to the Canadian Standards Association (CSA) requirements. New policies were put in place that in effect brought all equipment and surfacing into compliance with current CSA Standards. This resulted in a lower fall height for most play equipment. These guidelines also required that a minimum depth of at least 12 inches for granitic sand or wood chip products be installed and maintained. Again, it is important to point out these conditions did not exist prior to the study. The study conducted after the equipment and surface improvements did show a significant injury reduction, but nobody took into consideration the performance of the preexisting surfaces in the Toronto Schools or the fall height of the old play equipment that contributed to all the baseline injury data. So, what is the reason or reasons for the lower incidence in fractures and other serious injuries?

One Anaheim presenter secured copies of actual field drop test reports from the Toronto Public Schools. He concluded that the field test results showed excellent impact attenuation of less than 500 HIC and 100g was the reason for fewer injuries. The other presenter concluded that surfaces which are in compliance with the existing standard thresholds of 200g and 1000 HIC resulted in fewer injuries. Which conclusion is more compelling? The actual in-field drop test reports for the Toronto Public Schools demonstrate impact attenuation results were both 50% better than current threshold requirements of 1000 HIC and even 50% better than the proposed reduction to 700 HIC. There are other variables that were not taken into consideration in the Howard Study, which would add to this discussion, but that horse has already left the barn. So what else, if anything, does the study show?

First, we must consider the injury reduction results are based on lower equipment fall heights along with a minimum maintained 12 inch depth of surface materials. These conditions did not exist prior to the study. Regardless, the Howard Study demonstrates a lower HIC threshold will have a measurable reduction in frequency and severity of all fall-related injuries. The study also demonstrates not all sand performs equally. This granitic sand, which is found in Ontario Canada, has superior impact-attenuating properties, primarily because it is very uniform in particle size minimizing compaction characteristics.

Concluding thoughts

In conclusion, the ASTM Committee on Standards appeal was over nothing more than the timing of the release of the information presented. The appeal argued that the late distribution of the supporting documents in support of the negative voters’ position affected the voting results. These documents ultimately were discussed at two Subcommittee meetings. The discussion did little to persuade any voters one way or the other.

Using the Howard Study along with the actual on-site surfacing drop test results makes for a pretty good argument that fewer fall-related injuries, including fractures and head injuries, will occur on surfaces with impact thresholds, even lower than the proposed 700 HIC. These results can only be realized one of two ways: lower the fall heights or improve the performance of impact-attenuating surfacing systems. These surfacing systems must also be managed by conscientious and knowledgeable staff who implement a consistent inspection and maintenance program.

Moving forward, we might begin to see the real correlation between surface performance and severity of injury if actual field drop test results were taken immediately after every serious fall-related playground injury. Some are requesting this kind of data before voting to reduce HIC thresholds. For many legal reasons this is unlikely to happen. What we can do is use the best information available. The automotive industry has 50 years of experience in the area of impact injury research. Why not start with that?