Artificial turf is a popular ground cover for sports fields, playgrounds, and residential landscapes, prized for its durability and low maintenance requirements. However, a major concern is their tendency to absorb and retain solar energy, causing surface temperatures to soar. Artificial turf can get extremely hot, reaching temperatures significantly higher than the ambient air or natural grass under the same conditions. This heat buildup has prompted scientific investigation into the underlying mechanisms and the resulting safety risks for users.
The Science Behind Extreme Surface Temperatures
The extreme heat found on synthetic turf fields is rooted in the physical properties of the materials used. Unlike living grass, which is roughly 70% water, artificial turf is made from petroleum-based plastics (polyethylene, polypropylene, or nylon fibers) supported by an infill layer. This infill is often styrene-butadiene rubber (SBR) crumb rubber, which is dark and has a high thermal mass.
These synthetic components possess a low specific heat capacity, meaning they require little energy to dramatically increase in temperature. When exposed to direct sunlight, these materials rapidly absorb solar radiation rather than reflecting it. Consequently, the surface heats up quickly and retains that heat.
Natural grass fields utilize a process called evapotranspiration, where water evaporates from the soil and plant surfaces, drawing heat away and actively cooling the surface. Artificial turf lacks this natural cooling mechanism entirely, allowing absorbed solar energy to accumulate without a means of heat dissipation. This difference in thermal behavior is the primary reason synthetic surfaces become so much hotter than their natural counterparts.
Temperature Extremes and Real-World Comparisons
Studies have demonstrated that artificial turf surface temperatures can be tens of degrees hotter than surrounding natural surfaces. On a hot, sunny day, the temperature difference between synthetic turf and natural grass can range from \(60^\circ F\) to over \(80^\circ F\). While ambient air temperature might be in the low \(90^\circ F\) range, the turf surface itself can easily exceed \(140^\circ F\).
In one study, the surface temperature of artificial turf was recorded as high as \(200^\circ F\) on a \(98^\circ F\) day. For context, this material can become \(37^\circ F\) hotter than asphalt under the same conditions. The rapid heat absorption means that the surface can quickly become unsafe, even on days with moderate air temperatures.
The surface heat is primarily driven by solar radiation, not air temperature. This highlights the distinct thermal challenge posed by artificial turf compared to other common ground materials like concrete and natural soil.
Health and Safety Implications of Hot Turf
The extreme temperatures of synthetic turf present two main categories of risk to users, including athletes, children, and pets. The first is the risk of contact burns, or thermal injuries, from touching the superheated surface. Skin contact with surfaces at or above \(122^\circ F\) (\(50^\circ C\)) can cause injury in minutes.
Since turf temperatures frequently exceed this threshold, particularly during midday sun, players falling or sliding risk immediate skin damage. At temperatures around \(160^\circ F\) (\(71^\circ C\)), a burn can occur in less than a second, and this heat can penetrate the soles of shoes, causing blisters. This risk is heightened for children and pets who have prolonged contact with the ground.
The second major concern is systemic heat stress, caused by increased radiant heat exposure from the hot surface. The turf radiates heat upward, which elevates the core body temperature of anyone standing or exercising above it. This radiant heat can significantly increase the risk of heat-related illnesses, such as dehydration, heat exhaustion, and heat stroke. Elevated core temperatures have been observed in athletes training on hot artificial turf compared to natural grass.
Strategies for Reducing Turf Heat
Facility managers and homeowners have several strategies available to manage and reduce the high surface temperatures of artificial turf.
Evaporative Cooling and Specialized Infill
One immediate solution is evaporative cooling, which involves lightly spraying the turf with water. While effective, this cooling effect is temporary and may only last for 20 minutes before the temperature begins to rebound quickly. A longer-term solution involves specialized infill materials designed to retain moisture and cool the surface through evaporation. Products like HydroChill or other mineral-based infills absorb water and slowly release it, providing a more sustained cooling effect compared to standard rubber infill.
Material and Scheduling Adjustments
Modern turf manufacturing increasingly incorporates reflective coatings or pigments into the synthetic fibers themselves. These coatings are designed to reflect more solar energy before it can be absorbed and converted into heat. Other adjustments include choosing lighter-colored fibers or infills, as darker colors absorb more radiation. Simple measures such as implementing shade structures or scheduling activities for cooler periods, like early morning or late evening, can also mitigate extreme heat risks.