Safer Grass Options for Athletic Fields
Schools, universities, and municipalities often must choose between natural grass athletic fields and artificial turf. These considerations are multi-faceted and involve trade-offs.
Schools, universities, and municipalities often must choose between natural grass athletic fields and artificial turf. These considerations are multi-faceted and involve trade-offs.
Written by Susan Kaplan, Rachel Massey & Lindsey Pollard
Schools, universities, and municipalities often face the need to make a choice between natural grass athletic fields and artificial turf.
These choices can involve substantial monetary investments. Reasons some cite for choosing artificial turf can include an expectation of more playable hours; expectations of reduced water use and/or reduced maintenance needs; and the perception that it is the “premium” option.
However, these considerations are multi-faceted and involve trade-offs. For example, communities often face maintenance problems with an existing grass field, but do not fully explore the improvements in field quality and playable hours that can be obtained through better maintenance of grass fields. In addition, communities do not always take account of future needs related to maintenance, repair and eventual disposal of artificial turf.
The Toxics Use Reduction Institute (TURI) at the University of Massachusetts Lowell has worked with schools and other institutions to research best practices for creating and maintaining athletic fields that are cost-effective and preferable for human health and the environment. Sources of support for this work include the Pittsburgh-based Heinz Endowments.
Artificial turf lasts for eight to 10 years, after which it is typically disposed of in a landfill; while some components of the turf system may be reusable one or more times, others may have to be disposed of in a landfill or through incineration when the field is due for replacement, contributing to solid waste pollution. Environmental concerns also include loss of wildlife habitat when green space is replaced with synthetic turf, and migration of rubber and plastic particles into the environment, contributing to microplastic pollution.
From a climate change perspective, going with synthetic turf means loss of the potential to capture carbon in a healthy soil ecosystem. The loss of green space also contributes to the urban heat island effect.
Artificial turf does not eliminate the need for water; in some cases, it is irrigated with water in order to temporarily bring down high surface temperatures. Maintenance can include treatment with antimicrobials, as well as periodic addition of infill to replace the infill that migrates off the field into the environment. A recent article in Architectural Digest notes that artificial turf’s plastic material “traps heat during the day and holds it through the night, meaning runoff water will leave turf hotter than it would natural grass” - which can have negative effects on aquatic ecology.
Can artificial turf pollute the water or air? Evidence indicates cause for concern. Chemicals in tire crumb can volatilize into air or leach into rainwater. Some study results suggest that scrap tire materials in artificial turf may affect surface water or groundwater, warranting more study. Contaminants harmful to aquatic life, like zinc, have been found in stormwater runoff from artificial turf. For example, a study by the Connecticut Department of Environmental Protection noted high zinc concentrations in artificial turf stormwater runoff as a particular concern for aquatic organisms. It also noted the potential for leaching of copper, cadmium, barium, manganese and lead. A recent study found that a chemical derived from car tires, 6-PPD quinone, is lethal to coho salmon.
Recent research has identified per- and poly-fluoroalkyl substances (PFAS) in some artificial turf carpet materials. PFAS are a group of chemicals that are highly persistent in the environment; some can last for hundreds of years. PFAS have been found as drinking water contaminants in many states. Health effects documented for some PFAS include effects on the endocrine system, including liver and thyroid, as well as metabolic effects, developmental effects, neurotoxicity, and immunotoxicity. For more information, see TURI’s fact sheet on PFAS in artificial turf.
Health Concerns for Children
Chemicals in artificial turf fields are a particular concern for children. Children, including adolescents, are more vulnerable than adults to the effects of toxic chemicals. Their organ systems are developing rapidly, their detoxification mechanisms are still immature, and they breathe more air than adults relative to their body weight.
Concerns have been raised about chemicals in artificial grass carpet and in the infill that provides cushioning. Crumb rubber made from recycled tires (also known as “tire crumb”) is widely used as infill. It contains a large number of chemicals, many of which are known to be hazardous to human health and the environment; these include polyaromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and toxic metals such as lead. Some of these chemicals are known or suspected carcinogens.
Other synthetic infills include ethylene propylene diene terpolymer (EPDM) rubber, thermoplastic elastomers (TPE), waste athletic shoe materials, and acrylic-coated sand. These materials also contain chemicals of concern, although the total number of chemicals and/or the concentration of chemicals of concern may be lower than those found in tire crumb.
Naturally derived materials used as infill can include sand, zeolite, cork, coconut hulls, walnut shells, olive pits, and wood particles. While these materials likely contain fewer hazardous chemicals than tire crumb, many have not been studied thoroughly. Some plant-based materials raise concerns related to allergies or respirable fibers, and zeolite and sand can pose respiratory hazards. Exposure to some types of zeolites may be associated with increased risk of mesothelioma, a type of cancer. For more information on chemicals in infill materials, see TURI’s report, Athletic Playing Fields: Choosing Safer Options for Health and the Environment and the Healthy Building Network’s Turf Hazard Spectrum.
In sunny, warm weather, artificial turf can become much hotter than natural grass, raising concerns of heat-related illness and skin burns for athletes playing on the fields. The Penn State Center for Sports Surface Research measured surface temperature for infill alone, artificial grass fibers, and a full synthetic turf system. They found that all the materials reached higher temperatures than natural grass. With more hot days associated with climate change, this is a growing concern.
Heat-related illness can be a life-threatening emergency. Experts note that athletic coaches and other staff need to be educated about heat-related illness and understand how to prevent it, including cancelling sport activities when necessary.
Some school districts are addressing the surface temperature issue directly. For example, the school board of Burlington, MA adopted a policy requiring that an infrared heat gun be used to determine field surface temperature. The policy states conditions under which athletes may use artificial turf fields and when their activities must be moved to grass fields. For example, if the National Weather Service issues a heat advisory, artificial turf cannot be used for P.E. classes if the air temperature is more than 85 degrees and the humidity over 60 percent – then only a grass surface can be used.
Increased rates of skin abrasions (turf burns) have been associated with playing on artificial turf. These skin abrasions, in turn, are a risk factor for serious bacterial infections. A study by the California Office of Environmental Health Hazard Assessment found a two- to three-fold increase in skin abrasions per player hour on artificial turf compared with natural grass turf. Studies have implicated artificial turf as a source of methicillin-resistant Staphylococcus aureus (MRSA) in athletes. MRSA infections are a substantial and growing source of concern for athletes’ health.
Organically Managed Grass Athletic Fields
Research and case studies have identified a range of benefits of natural grass fields for environmental and public health protection, especially when they are managed organically. Case studies find that natural grass fields are cost effective and can fully meet communities’ needs for ample play time.
Organic maintenance practices can improve soil health and eliminate the need for synthetic pesticides or fertilizers. These practices focus on frequent aeration and mowing, as well as soil testing and use of organic fertilizers and soil amendments.
For many communities, the first steps are to diagnose existing problems on a grass field, find guidance, and determine whether the field needs to be rebuilt, or can simply be rehabilitated through improved maintenance.
Soil testing provides information on the physical, chemical, and biological characteristics of soil on a field. Results serve as a stepping-off point to creating a customized maintenance program for individual fields. Using this tailored approach helps avoid overapplication of fertilizers and soil amendments. In addition to finding out about the physical and chemical composition of the soil, communities can use soil testing to assess the health of the community of soil microorganisms.
Rehabilitation vs. Rebuilding
Field rehabilitation focuses on correcting problems, such as water pooling, weeds, or uneven grass cover, by improving the quality of the existing soil and grass. With these steps, many find that their playing fields need no other interventions.
Rebuilding a playing field offers the advantage of designing a field for optimum performance, including optimizing drainage, irrigation, and soil composition.
Taking Action: Best Practices for Organic Maintenance
Maintenance of natural grass can include watering, mowing, fertilizing, replacing sod, and other activities.
Choice of fertilizer is a key component of sustainable natural grass management. Organic (or carbon-based) fertilizer is made with natural, plant- or animal-derived ingredients. For example, fertilizers can be made from soybean meal, feather meal, or animal products. Practices to increase organic matter in the soil will also build soil health and reduce fertilizer needs over time. Use of soil amendments also depends on soil testing, and may include addition of soil conditioner, compost, or lime. Adding compost can also increase diversity of microbes, including fungi and nematodes, which can improve disease resistance.
The term organic fertilizer sometimes refers to any naturally derived, carbon-based fertilizer such as those made from plant or animal products. This does not necessarily mean that a product is certified organic, which provides information about specific standards used in production.
Selecting the appropriate type of grass seed is critical. Individual grass species offer different protective capabilities, such as heat or cold tolerance, drought resistance, deep root systems, and weed resistance. For example, at Denison University in Granville, Ohio, the varsity soccer field is planted with bermudagrass and ryegrass. Bermudagrass goes dormant in winter, while ryegrass goes dormant in hot weather. In combination, the two grass types provide a play surface that performs well in a variety of weather conditions.
Aeration relieves compacted soil and dethatches grass to allow air, water, and added nutrients to penetrate the soil. Relieving compaction can improve drainage, decrease the need for irrigation, and create a softer, more protective playing surface. Consultants typically recommend aerating several times per year. The City of Springfield, Massachusetts, for example, aerates its organically managed fields four times per year.
For more information about organic grass management, see TURI’s fact sheet, “Building an Organic Maintenance Program for Athletic Fields: Guidance from Experts and Experienced Communities” (PDF). The article “How to Avoid Greenwashing and Harmful Pesticides in Lawn Care” may also be of interest.
For those communities that choose artificial turf, maintenance is also necessary. Maintenance of artificial turf systems can include fluffing, redistributing and shock testing infill; periodic disinfection of the materials; seam repairs and infill replacement; and watering to lower temperatures on hot days.
Quality and Playable Hours
Communities often have questions about whether they can fully meet the need for athletic play time using natural grass. Case studies have found that when communities invest in organic management of natural grass, or even just use some of the key best practices of sustainable grass management, they can achieve a substantial increase in playable hours.
TURI has documented the details of playable hours for three communities (VIDEO) in Massachusetts. For example, since starting an organic program for its sports fields, parks areas and other public properties in 2014, the city of Springfield, Massachusetts has doubled the number of properties in the program and experienced an increase in overall recreational use due to the improvement in soil and grass conditions. Hours of practice, play and informal activity on Treetop Park, a soccer field, totaled just over 1,000 hours in 2018.
In another example, the Borough of Heidelberg, Pennsylvania chose to improve the athletic field at Heidelberg Park using organic methods. The field is primarily used by children for soccer, football, cricket and softball practices. Poor initial soil quality led to severely compacted soil with poor drainage. The Natural Grass Advisory Group worked with the borough to improve the field using soil testing, aeration, and addition of fertilizer and soil amendments to build soil health and foster the development of a robust root system. After one year, the field had thicker grass cover and a smoother, softer surface.
Flooding of grass fields can be remedied through improved drainage. For example, since Denison University rebuilt its natural grass varsity soccer field to address drainage issues, it has had no cancellations due to rain and athletes can play on it even after heavy rain. In fact, it went from being the lowest-performing field, with frequent standing water, to a high-performing field that visiting teams often request to play on.
Organic turf maintenance can be cost-competitive with conventional management. One study found that once established, an organic turf management program can cost 25% less than a conventional turf management program. In TURI’s 2019 case study, Springfield, Massachusetts officials estimated that the annual total for products, maintenance and labor for organic grass maintenance was just under $1,500 per acre.
Denison University’s cost for 21 acres of natural grass field maintenance is just under $1,800 per acre, not including costs of pesticides. Its staff state that the cost of products for natural grass management is falling as interest and demand in this area grow. The grounds manager has found that the grass fields are far more cost effective than the university’s one artificial turf field once the full costs are factored in. Denison resurfaces its artificial turf field every seven to eight years, at a cost of about $800,000, and spends about $115,000 annually for maintenance.
More detail about playable hours, maintenance, costs and more can be found in the case studies and other resources listed below.
Environmental and Health Benefits
Organically or sustainably managed natural grass fields offer a variety of benefits.
Natural grass athletic fields may require irrigation at times. However, following organic management practices reduces water needs by supporting root development. Using a “smart” irrigation system, as described in the Martha’s Vineyard case study, can maximize benefits while conserving water.
Well-designed and maintained grass fields absorb rain. Some schools and communities interested in environmental sustainability pair grass athletic fields or other green spaces with stormwater management features like rain gardens and include educational signage about their benefits.
Conventionally managed natural grass may be treated with synthetic pesticides or fertilizers. Some commonly used pesticides are linked with serious health impacts, including asthma, Parkinson’s disease, fertility-related problems, and cancer.
Organically managed natural grass builds soil health, making it unnecessary to apply chemical treatments. Organic fertilizer is better absorbed than synthetic fertilizer, which means less runoff that can contribute to algae blooms.
Grassy areas help to reduce the urban heat island effect. Natural grass athletic fields do not heat up the way artificial turf fields do. The school board of Burlington, MA adopted a policy that delineates heat and humidity conditions under which athletes may not use artificial turf fields and must move to grass fields to protect them from heat-related health concerns. And scientists are investigating soil as a potential carbon “sink” that can contribute to carbon sequestration, pointing to an additional possible benefit of grass.
Grass fields, especially managed organically, may align with policies or programs such as climate change action plans or green certification programs like the Sustainable Sites Initiative. Natural grass also provides habitat for a range of organisms; organic practices protect pollinators.
Analyze the full costs and benefits of the options available to your community. Start by reviewing your existing maintenance practices on grass fields. Is there an opportunity to improve existing maintenance before making an investment in a new system? If the community is ready to make a major capital investment, consider the option of rebuilding an existing grass field. As one example, Denison University rebuilt its natural grass varsity soccer field to address drainage issues; since rebuilding, it has had no cancellations due to rain.
Consider the full life cycle of a field. For example, evaluations should include the environmental and financial costs of maintaining artificial turf, as well as disposal and replacement after eight to ten years.
Consider how these questions align with related community goals or policies, such as climate change action plans.
If considering the option of removing artificial turf or wondering about how best to address a grass athletic field that has challenges like weeds or poor drainage, consult a professional who specializes in athletic field maintenance practices. A TURI report provides information about rehabilitation and rebuilding of natural grass fields and lists several consulting and educational organizations that focus on the use of organic management techniques.
The Field Fund in Martha’s Vineyard provides information on natural grass management
Phipps Conservatory – offers a Sustainable Landcare Accreditation course
About The Authors
Susan Kaplan is an environmental health lawyer and a professor at the University of Illinois Chicago School of Public Health. She contributes to projects at the Toxics Use Reduction Institute on a consulting basis.
Dr. Rachel Massey is Senior Associate Director and Policy Analyst at the Toxics Use Reduction Institute at the University of Massachusetts Lowell. Her work includes policy analysis at the state, federal and international levels, as well as work with communities to reduce toxics at the local level.
Lindsey Pollard is Special Projects Research Associate at the Toxics Use Reduction Institute at the University of Massachusetts Lowell. Her work includes policy research, researching chemical hazards associated with consumer materials, finding safer alternatives and sharing findings with communities.