Abstract
OBJECTIVE:
To examine the effect of season on playground surface injury rates.
METHODS:
Injuries were identified through student incident report forms used in school districts in Calgary (Alberta) and the surrounding area. Playground surface exposure data were estimated based on school enrollment.
RESULTS:
A total of 539 injuries were reported during the 2007/2008 school year. Abrasions, bruises and inflammation were the most frequently reported injuries. The head, neck or face were most commonly injured. Injury rates per 1000 student days ranged between 0.018 (rubber crumb in spring) and 0.08 (poured-in-place and natural rock in the fall). Rubber crumb surfacing, compared with natural rock, had a significantly lower rate of injury in the spring, but no other season-surface comparisons were statistically significant.
CONCLUSIONS:
Rates of injury were similar for natural rock, poured-in-place, and crushed rock in the fall and winter. There was some evidence of a lower rate of injury on rubber crumb surfaces in the spring.
Keywords: Children, Injury, Play, School
Abstract
OBJECTIF :
Examiner l’effet de la saison sur le taux de blessures subies à cause des surfaces des terrains de jeux.
MÉTHODOLOGIE :
Les chercheurs ont recensé les blessures grâce aux formulaires d’incidents chez les élèves utilisés, dans les districts scolaires de Calgary (Alberta) et de la région avoisinante. Ils ont évalué les données d’exposition aux surfaces de jeu d’après les inscriptions à l’école.
RÉSULTATS :
Au total, 539 blessures ont été déclarées pendant l’année scolaire 2007–2008. La blessure la plus courante était une abrasion, une ecchymose ou une inflammation. La tête, le cou ou le visage étaient les plus touchés. Le taux de blessures sur 1 000 jours-élèves variait entre 0,018 (miettes de caoutchouc au printemps) et 0,08 (béton coulé et roche naturelle à l’automne). Par rapport à la roche naturelle, les surfaces de miettes de caoutchouc s’associaient à un taux de blessures beaucoup moins élevé au printemps, mais aucune autre comparaison des surfaces selon les saisons n’était statistiquement significative.
CONCLUSIONS :
Le taux de blessures était similaire pour la roche naturelle, le béton coulé et la roche concassée à l’automne et pendant l’hiver. On remarquait certaines données probantes quant à un taux moins élevé de blessures sur les surfaces de miettes de caoutchouc au printemps.
Each year, an estimated 20,000 to 30,000 children in Canada are treated in hospital emergency departments for playground-related injuries (1). In Canada, approximately 2500 children 14 years of age and younger are admitted to hospital for serious injuries resulting from a playground fall every year (2). Studies show that 67% of playground injuries are caused by falls from equipment to the ground, and that the height of fall is a risk factor for injury (3,4) and severe injury (5). These falls usually occur from equipment such as monkey bars, track rides and jungle gyms that require upper body strength (6,7). In Canada, 36% of playground injuries occur on school playgrounds and 57% of playground injuries are sustained by children five to nine years of age (3). Since the introduction of playground safety standards, severe head injuries have become increasingly rare (8,9). Fracture of the upper extremities is the most common playground injury (10,11).
The Canadian Standards Association, an organization that develops product standards to promote public safety and health, recognizes playground surfacing as one of the main risk factors for playground injury (12). The literature also shows an increased risk of injury when falling on to a non-impact-absorbing surface (4,13). To comply with the Canadian Standards Association, surfacing under playground equipment must be able to attenuate impact to a specific standard as measured by the Head Injury Criterion (HIC) and, therefore, reduce the risk of serious injury from a fall.
Studies investigating surface-specific injury rates show an increased risk of injury when falling onto a non-impact-absorbing surface. Sosin et al (14) found the injury rate for asphalt to be six times that of sand, with rubber mats and gravel having rates twice that of sand. Mott et al (6) confirmed the protective effect of impact-absorbing surfaces, finding concrete to have an injury rate five times that of rubber.
Chalmers et al (4) obtained similar results, finding the likelihood of being injured in a fall on a non-impact-absorbing surface was 2.28 times that of a fall onto an impact-absorbing surface. Howard et al (15) compared upper extremity fracture rates in schools with wood fibre surfacing with those with granite sand surfacing. With the wood fibre surfacing, the risk of an arm fracture was 4.9 times higher than the granite sand surfacing.
Playground surfaces are dynamic in that extreme temperatures and weather conditions influence their ability to attenuate impact, which potentially has serious implications for injury risk. In a laboratory-based study, Mack et al (16) found pea gravel to have low impact attenuation under all tested conditions and recommended that playground providers abstain from installing it. Lewis et al (17) tested wood chips, sand, grass, rubber matting and gravel under four environmental conditions simulated in a laboratory: dry and warm, dry and frozen, wet and warm, and wet and frozen. Wood chip surfacing had the best impact attenuation in all of the environmental conditions except for wet and frozen, in which gravel had the lowest HIC score. These differences illustrate the need for a playground study to be conducted in situ.
Studies that have examined the effect of environmental conditions on the impact attenuation properties of playground surfacing, under conditions of actual use, have also reported mixed findings. Vidair et al (18) tested HIC values of poured-in-place surfaces at various temperatures as part of a larger study conducted to evaluate the risk of serious head injury due to falls on California (USA) playground surfaces made of recycled tires. High temperatures were found to increase the HIC score of poured-in-place surfacing, which reduces the ability of the surface to attenuate impact.
Sherker et al (19) monitored the in situ performance of tanbark, a wood chip surfacing, by placing two samples in three school playgrounds. The school playground samples were compared with two control samples. One control sample was kept inside a laboratory and the other was kept outdoors and exposed to similar weather conditions as the playground samples. Significant changes in surface depth and impact attenuation were detected in all samples after a period of eight weeks. The playground surfacing in ‘low use’ areas deteriorated slower than playground surfacing in ‘high use’ areas. Little difference between the surface changes to the indoor and outdoor control samples were found. This suggests that the performance of tanbark deteriorates regardless of weather.
No study has related injury rates on playground surfaces to season; therefore, the objective of the present study was to determine whether season affects the injury rate and injury profile of playground surfacing used in elementary schools from the school districts in Calgary (Alberta) and the surrounding area under conditions of actual use.
METHODS
A retrospective cohort study design was used and the study population consisted of students in elementary schools from school districts in Calgary and the surrounding area. The cohort was divided into groups according to the type of playground surfacing used at the schools. Student incident report forms (SIRFs), completed for all incidents involving bodily injury to a student, were used to identify playground injury events for the 2007/2008 school year. SIRFs, signed by the principal, must be sent to Calgary and the surrounding area school district’s elementary school management within 24 h of an incident.
One of the study authors (LB) extracted information from the SIRFs. The SIRFs, completed by a school staff member with first-aid training, contain information regarding the injury event. The age and grade of the injured student were collected. Additionally, the date and time of the incident, school at which the incident occurred, specific location of the incident, severity, type of injury and treatment details were collected.
Injured students were divided into two age categories: four to eight years of age and nine to 12 years of age, which are kindergarten to grade 3 and grade 4 to grade 6, respectively. These represent two reasonably homogenous groups. Severity was classified as high (ambulance required), medium (medical attention recommended) or low (minor first aid). Mean daily temperature in degrees Celsius and total daily precipitation were collected from the Environment Canada weather archives for the days when playground injuries occurred (20,21).
Enrollment information was used to determine the potential number of children exposed to each type of playground surface. Exposure was calculated by multiplying the number of enrolled students (categorized according to sex and grade) by the number of dry and wet days, according to the Environment Canada archives (20,21), and the number of days warmer than or equal to 1°C and colder than 1°C during each semester, to more accurately reflect use under different environmental conditions. For schools with more than one type of surface, exposure was calculated by multiplying the total exposure for the school by the proportion of playgrounds at that school with that particular surfacing. For example, exposure for a school with three playgrounds with two types of surfacing exposure would be calculated as follows:
Crushed rock, natural rock, poured-in-place, rubber crumb and rubber tile are the five types of playground surfacing used in elementary schools from the school districts in Calgary and the surrounding area. Only one playground in the school districts from Calgary and the surrounding area had rubber tile surfacing; therefore, this school was excluded from the analysis. The installation years for each type of surface ranged from 1975 to 2007 (crushed rock 1975 to 2002; natural rock 1989 to 2007; poured-in-place 1998 to 2007; rubber crumb 1999 to 2001).
Although crushed rock and natural rock are both commonly known as pea gravel, they have different physical characteristics; therefore, they were examined separately. It is important to note that the different physical characteristics of gravel have implications for playground safety. Because it is manufactured by being crushed or broken, crushed rock has jagged edges. These edges do not allow for the displacement of the particles (22) and, with regular usage, the gravel can break down into smaller particles. The smaller particles pack together and form into a hardpan crust two to three inches below the surface of the loose crushed rock and does not attenuate impact (W Baptist, the City of Calgary, August 12, 2010, personal communication).
Natural rock is derived from natural stones that have been screened to achieve the correct size (W Baptist, the City of Calgary, August 12, 2010, personal communication). This gravel has naturally round edges that allow it to displace properly. Natural rock does not break down into smaller particles and does not form a hardpan crust.
Data analysis
Information on the distribution of injuries according to severity, type of equipment and nature of injury according to age group is presented in Tables 1 to 4. These characteristics are also tabulated for each type of surface. Injury rates per 1000 student days are presented for each surface and season combination. Injury rate ratios with 95% CIs are presented for the comparison of each surface type with natural rock in each season. Poisson regression with adjustment for clustering by school to adjust these surfaces by season rate comparisons for age, sex, precipitation and temperature was used. All analyses were conducted using Stata SE version 11.2 (StataCorp, USA).
TABLE 1.
Playground equipment injuries in children four to 12 years of age in elementary schools from school districts in Calgary (Alberta) and the surrounding area according to age, sex, severity of injury, type of equipment and nature of injury
|
Age, years
|
Total | ||
|---|---|---|---|
| 4–8 | 9–12 | ||
| Sex | |||
| Male | 192 (57.1) | 66 (48.2) | 258 (54.5) |
| Female | 139 (41.4) | 68 (49.6) | 207 (43.8) |
| Unspecified | 5 (1.5) | 3 (2.2) | 8 (1.7) |
| Total | 336 (100) | 137 (100) | 473 (100) |
| Severity of injury | |||
| High | 2 (0.6) | 6 (4.4) | 8 (1.7) |
| Medium | 93 (27.7) | 46 (33.6) | 139 (29.4) |
| Low | 222 (66.1) | 77 (56.2) | 299 (63.2) |
| Unspecified | 19 (5.6) | 8 (5.8) | 27 (5.7) |
| Total | 336 (100) | 137 (100) | 473 (100) |
| Type of equipment | |||
| Monkey bar or bar | 106 (31.5) | 46 (33.6) | 152 (32.1) |
| Slide | 43 (12.8) | 17 (12.4) | 60 (12.7) |
| Glider | 25 (7.4) | 20 (14.6) | 45 (9.5) |
| Unspecified* | 35 (10.4) | 7 (5.1) | 42 (8.9) |
| Swing† | 24 (7.1) | 13 (9.5) | 37 (7.8) |
| Climber‡ | 28 (8.5) | 7 (5.1) | 35 (7.4) |
| Pole | 21 (6.2) | 5 (3.7) | 26 (5.5) |
| Steps, ladder§ | 19 (5.7) | 7 (5.1) | 26 (5.5) |
| Other¶ | 18 (5.4) | 6 (4.4) | 24 (5.1) |
| Bridge | 10 (2.9) | 6 (4.4) | 16 (3.4) |
| Platform | 7 (2.1) | 3 (2.2) | 10 (2.1) |
| Total | 336 (100) | 137 (100) | 473 (100) |
| Nature of injury | |||
| Abrasion/bruise/inflammation** | 168 (50.0) | 44 (32.1) | 212 (44.8) |
| Soreness/pain | 56 (16.7) | 44 (32.1) | 100 (21.1) |
| Cut/laceration†† | 36 (10.7) | 12 (8.8) | 48 (10.2) |
| Fracture/dislocation/pulled muscle | 20 (6.0) | 10 (7.3) | 30 (6.3) |
| Minor head injury/concussion | 18 (5.4) | 6 (4.4) | 24 (5.1) |
| Unspecified | 12 (3.6) | 7 (5.1) | 19 (4.0) |
| Dental injury | 12 (3.6) | 5 (3.7) | 17 (3.6) |
| No injury | 11 (3.3) | 6 (4.4) | 17 (3.6) |
| Other‡‡ | 3 (0.9) | 3 (2.2) | 6 (1.3) |
| Total | 336 (100) | 137 (100) | 473 (100) |
Data presented as n (%).
Includes play structure and play equipment;
Includes disc swing, pizza swing, tire swing and saucer swing;
Includes corkscrew, climbing wall, rock climber, igloo, tower, spider web, rope climber and rope;
Includes toadstool and stepping stones;
Includes x-wave, super-nova, rocker, rocket, metal stool, spinner, boards, bench, ball, ice cream parlor, twister, spinning wheel, twirling device, moving wheel and teeter-totter;
Includes lumps, bumps, scratch, scrape, goose egg, rope burn, swelling, redness, fat lip, bumped and hit;
Includes split open and bitten lip;
Includes puncture, foreign body, winded and blister
TABLE 4.
Poisson regression adjusted* rate ratio estimates of surface according to season
|
Rate ratio (95% CI)
|
|||
|---|---|---|---|
| Fall | Winter | Spring | |
| Natural rock | 1.0 (reference) | 1.0 (reference) | 1.0 (reference) |
| Crushed rock | 0.78 (0.50–1.22) | 1.25 (0.68–2.27) | 1.10 (0.67–1.81) |
| Poured-in-place | 1.06 (0.59–1.93) | 1.40 (0.71–2.75) | 0.86 (0.52–1.43) |
| Rubber crumb | 0.91 (0.30–2.75) | 0.79 (0.22–2.78) | 0.34 (0.12–0.98) |
Adjusted for age, sex, precipitation and temperature, and clustering by school
RESULTS
In total, 539 playground-related incidents were reported on SIRFs in elementary schools from the school districts in Calgary and the surrounding area in the 2007/2008 school year. Information regarding age and grade were missing from 66 of the SIRFs. These students were excluded from the age-specific analysis.
The largest proportion of injuries (336 of 473 [71%]) occurred among children four to eight years of age (Table 1). Males accounted for 54.5% of the playground-related injuries and the majority of total injuries (63.2%) were classified as low severity.
The top five types of equipment involved in playground injuries were monkey bars or bars (32.1%), slides (12.7%), gliders (9.5%), swings (7.8%) and climbers (7.4%). Equipment was unspecified for 8.9% of injuries. An abrasion/bruise/inflammation was the predominant injury type, accounting for 44.8% of all injuries, followed by soreness/pain (21.1%), cut/laceration (10.2%), fracture/dislocation/pulled muscle (6.3%) and minor head injury or concussion (5.1%). In both age groups, either abrasion/bruise/inflammation or pain/soreness accounted for more than 60% of injuries (66.7% for four to eight years olds, 64.2% for nine to 12 year olds).
The largest proportion of injuries (48%) occurred on natural rock followed by crushed rock (36.4%) (Table 2) – reflecting fairly closely the distribution of these surfaces at the playgrounds. On natural rock, injuries occurred most frequently on monkey bars or bars, slides and unspecified. On crushed rock, injuries occurred most frequently on monkey bars or bars, slides and swings. On poured-in-place surfaces, monkey bars or bars, gliders, unspecified and poles were the pieces of equipment most commonly involved in injuries.
TABLE 2.
Playground equipment injuries in elementary schools from school districts in Calgary (Alberta) and the surrounding area according to surface and type of equipment, nature of injury and body region injured
|
Surface
|
Total | |||
|---|---|---|---|---|
| Natural rock | Crushed rock | Poured-in-place | ||
| Type of equipment | ||||
| Monkey bar or bar | 76 (30.2) | 68 (35.6) | 17 (20.7) | 161 (30.7) |
| Slide | 32 (12.7) | 29 (15.2) | 9 (11.0) | 70 (13.3) |
| Glider | 20 (7.9) | 16 (8.4) | 12 (14.6) | 48 (9.1) |
| Unspecified* | 28 (11.1) | 11 (5.8) | 12 (14.6) | 51 (9.7) |
| Swing† | 22 (8.7) | 19 (9.9) | 5 (6.1) | 46 (8.8) |
| Climber‡ | 23 (9.1) | 7 (3.7) | 6 (7.3) | 36 (6.9) |
| Pole | 6 (2.4) | 12 (6.3) | 11 (13.4) | 29 (5.5) |
| Steps, ladder§ | 14 (5.6) | 8 (4.2) | 4 (4.9) | 26 (5.0) |
| Other¶ | 13 (5.2) | 9 (4.7) | 5 (6.1) | 27 (5.1) |
| Bridge | 9 (3.6) | 10 (5.2) | 0 (0) | 19 (3.6) |
| Platform | 9 (3.6) | 2 (1.1) | 1 (1.2) | 12 (2.3) |
| Total | 252 (100) | 191 (100) | 82 (100) | 525 (100) |
| Nature of injury | ||||
| Abrasion/bruise/inflammation** | 115 (45.6) | 88 (46.1) | 31 (37.8) | 234 (44.6) |
| Soreness/pain | 56 (22.2) | 35 (18.3) | 21 (25.6) | 112 (21.3) |
| Cut/laceration†† | 26 (10.3) | 26 (13.6) | 4 (4.9) | 56 (10.7) |
| Fracture/dislocation/pulled muscle | 8 (3.2) | 16 (8.4) | 7 (8.5) | 31 (5.9) |
| Minor head injury/concussion | 17 (6.7) | 4 (2.1) | 5 (6.1) | 26 (5.0) |
| Dental injury | 6 (2.4) | 6 (3.1) | 5 (6.1) | 17 (3.2) |
| Unspecified | 12 (4.8) | 8 (4.2) | 5 (6.1) | 25 (4.8) |
| No injury | 11 (4.4) | 4 (2.1) | 3 (3.7) | 18 (3.4) |
| Other‡‡ | 1 (0.4) | 4 (2.1) | 1 (1.2) | 6 (1.1) |
| Total | 252 (100) | 191 (100) | 82 (100) | 525 (100) |
| Body part | ||||
| Head, neck or face | 150 (59.5) | 118 (61.8) | 54 (65.9) | 322 (61.3) |
| Upper limbs | 30 (11.9) | 33 (17.3) | 12 (14.6) | 75 (14.3) |
| Lower limbs | 22 (8.7) | 17 (8.9) | 8 (9.8) | 47 (9.0) |
| Trunk | 39 (15.5) | 17 (8.9) | 7 (8.5) | 63 (12.0) |
| Groin or hip | 9 (3.6) | 4 (2.1) | 0 (0) | 13 (2.5) |
| Unspecified | 2 (0.8) | 2 (1) | 1 (1.2) | 5 (1.0) |
| Total | 252 (100) | 191 (100) | 82 (100) | 525 (100) |
Data presented as n (%).
Includes play structure and play equipment;
Includes disc swing, pizza swing, tire swing and saucer swing;
Includes corkscrew, climbing wall, rock climber, igloo, tower, spider web, rope climber and rope;
Includes toadstool and stepping stones;
Includes x-wave, super-nova, rocker, rocket, metal stool, spinner, boards, bench, ball, ice cream parlor, twister, spinning wheel, twirling device, moving wheel and teeter-totter;
Includes lumps, bumps, scratch, scrape, goose egg, rope burn, swelling, redness, fat lip, bumped and hit;
Includes split open and bitten lip;
Includes puncture, foreign body, winded and blister
For all three surfaces, abrasion/bruise/inflammation was the most common injury followed by soreness/pain – these two categories of injury accounted for 67.8% of injuries on natural rock, 64.4% on crushed rock and 63.4% on poured-in-place surfaces. The head, neck and face was the body region most commonly injured for all three surfaces.
Because only 14 injuries occurred on rubber crumb surfaces, these injuries were not included in Table 2, but are reported here. Five occurred on a monkey bar or bar, four on a glider and the remainder on five other pieces of equipment. The two most common injuries were abrasion/bruise/inflammation and soreness/pain. The nature of injury included two fracture/dislocation/pulled muscle, one cut/laceration, one minor head injury/concussion and one dental injury. Eleven of 14 of these injuries were to the head and neck.
Injury rates per 1000 student days ranged between 0.018 for rubber crumb surfacing in spring and 0.08 for poured-in-place and natural rock surfacing in the fall (Table 3). Without adjustment for covariates, crushed rock surfacing demonstrated the lowest injury rate in the fall, while rubber crumb surfacing demonstrated the lowest injury rate in the winter and spring. Natural rock was the baseline for comparison because the highest number of injuries occurred on it. In the fall, compared with natural rock surfaces, crushed rock had a rate ratio (RR) of 0.76 (95% CI 0.57 to 1.01) and poured-in-place had a RR of 1.0 (95% CI 0.68 to 1.44). Rubber crumb was estimated to have a lower RR than natural rock in the fall (RR 0.86 [95% CI 0.38 to 1.68]). In the winter, crushed rock (RR 1.20 [95% CI 0.78 to 1.82]) and poured-in-place (RR 1.37 [95% CI 0.78 to 2.33]) surfaces had higher RR, although non-statistically significant, injury rates compared with natural rock. Rubber crumb surfacing had a lower, but again, nonstatistically significant injury rate in the winter compared with natural rock.
TABLE 3.
Playground equipment injuries in elementary schools from school districts in Calgary (Alberta) and the surrounding area according to surface and season
| Surface |
Fall
|
Winter
|
Spring
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Injuries, n | Exposure* | Rate† | Rate ratio (95% CI) | Injuries, n | Exposure* | Rate† | Rate ratio (95% CI) | Injuries, n | Exposure* | Rate† | Rate ratio (95% CI) | |
| Natural rock | 128 | 1,599,559.5 | 0.080 | 1.0 (reference) | 49 | 1,017,901.5 | 0.048 | 1.0 (reference) | 75 | 1,329,504 | 0.056 | 1.0 (reference) |
| Crushed rock | 78 | 1,282,678.8 | 0.061 | 0.76 (0.57–1.01) | 47 | 816,250.2 | 0.058 | 1.20 (0.78–1.82) | 66 | 1,066,122.7 | 0.062 | 1.10 (0.78–1.55) |
| Poured-in-place | 40 | 498,754.7 | 0.08 | 1.0 (0.68–1.44) | 21 | 317,389.3 | 0.066 | 1.37 (0.78–2.33) | 21 | 414,549.3 | 0.051 | 0.90 (0.53–1.47) |
| Rubber crumb | 9 | 131,285 | 0.069 | 0.86 (0.38–1.68) | 3 | 83,545 | 0.036 | 0.75 (0.15–2.31) | 2 | 109,120 | 0.018 | 0.32 (0.04–1.22) |
Number of student days;
Per 1000 student days
The rates were similar for natural rock, poured-in-place and crushed rock surfaces in the spring. However, rubber crumb surfacing had a lower, although not statistically significant, rate of injury in the spring compared with natural rock (RR 0.32 [95% CI 0.04 to 1.22]).
The season according to surface effects were consistent after adjustment for age, sex, temperature and weather conditions in a multiple regression Poisson model (Table 4).
DISCUSSION
Playground safety involves the interaction of many factors. The present study has provided a season-specific profile of playground injuries in elementary schools from the school districts in Calgary and the surrounding area.
Several of our findings are consistent with previous literature. The finding that the highest proportion of playground injuries involves monkey bars or bars, slides and gliders is consistent with previous findings such as the Canadian Hospitals Injury Reporting and Prevention Program’s (CHIRPP) Playground Injury Report (10). The finding that younger school-age children experience the largest proportion of injuries is also consistent with the CHIRPP report, which identified five to nine year olds as experiencing the majority of playground injuries (3).
Based on emergency department recruitment, it has been reported in the literature that fractures to the upper extremities are the most common playground injury (8,11,22). The findings of the present study from playground injury reports show that the head/neck/face is the most common body part injured on playgrounds in the school districts in Calgary and the surrounding area. The upper limb was the second most common body part injured, but upper limb fracture/dislocation/pulled muscle accounted for only 4.4% of the overall injuries. It should be noted that previous studies that reported high rates of playground-related arm fracture identified cases by reviewing emergency department charts (5,8,13), as opposed to investigating all playground injuries that occur in a school district. This discrepancy is, therefore, likely due to the different populations studied and different methods for identifying a case of fracture/dislocation/pulled muscle. Additionally, in our study, the individuals completing the SIRFs are only required to have basic medical training and, therefore, may be unable to accurately identify a fracture/dislocation/pulled muscle.
A large difference in the injury rates among the surfaces within a single season was not observed. The findings of the present study are consistent with the findings of Chalmers et al (4), who did not find a difference in injury risk associated with falling onto a synthetic rubber surfacing compared with loose-fill surfacing. Our findings are likely generalizable to locations with comparable seasonal weather patterns.
Limitations
There are several limitations associated with using SIRFs. The individual who completed the SIRF was only required to have basic medical training; therefore, it is reasonable to assume that they may have misclassified injury type and severity. In addition, the description of the incident itself may be inaccurate because the individual completing the form is not required to have witnessed the incident. There may also have been differential reporting of injuries by schools, although it is unlikely that these differences in reporting practices would be associated with school playground, surface type or season.
Another limitation is the assumption that playgrounds at elementary schools from the school districts in Calgary and the surrounding area were used equally. Precise use time of playgrounds was not measured and, therefore, exposure was not adjusted according to playground hours of use. Further to this, where a school had more than one type of playground surface it was assumed that they were being played on equally. However, Sosin et al (14) acknowledged that multiple factors including equipment design and the age of a playground influence its appeal to users.
There was no information on the lifespan of each playground surface readily available. The authors recognize that a number of variables, such as installation, playground manufacturer, maintenance, usage and climate, may affect the lifespan of a playground.
CONCLUSION
For elementary schools in the school districts in Calgary and the surrounding area, a majority of the playground injuries are suffered by children four to eight years of age, and more than one-half of the injuries were classified as being a low level of severity. Only 1.7% of injuries required an ambulance. The most common piece of equipment involved in an injury was a monkey bar or bar. An abrasion/bruise/inflammation was the most frequent injury and the head/neck/face was the most common body part injured. Rates of injury were similar for natural rock, poured-in-place and crushed rock surfaces in the fall and winter. There was some evidence of a lower rate of injury on rubber crumb surfaces in the spring. Our findings suggest that although the surfaces we examined generally have a low injury rate, the installation of rubber crumb surfacing can significantly reduce the risk of injury in elementary school playgrounds. However, cost and accessibility must also be considered. The evidence presented here will be useful for schools considering playground equipment and surfacing options.
Acknowledgments
The authors thank Raymond Hauck, playground safety inspector, for providing helpful information on Calgary and area school districts playgrounds and Wayne Baptist, Amenities Supervisor, Parks, City of Calgary, for providing background information on playground surfacing. Dr Brent Hagel holds the Alberta Children’s Hospital Foundation Professorship in Child Health and Wellness, funded through the support of an anonymous donor and the Canadian National Railway Company, as well as the Alberta Heritage Foundation for Medical Research Population Health Investigator and Canadian Institutes of Health Research New Investigator Awards.
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