Turf Battles and Plant Physics

April 4, 2008

Stuart Gaffin is a climate researcher at Columbia University  and is a regular contributor with his blog “Exhausted Earth”. Reuters is not responsible for the content — the views are the author’s alone.

Houston Astros pitcher Mike Hampton pitches against the Philadelphia Phillies during the first inning at the Astrodome in Houston September 13. Hampton was contending for his 20th win of the 1999 season. BRD/JPAn interesting environmental debate is taking place with regard to the growing proliferation of synthetic turf sports fields in outdoor settings.

These fields are modern versions of the original “AstroTurf” installed inside the Houston Astrodome in the late 1960s, after it was found living turf grass would not survive there. Synthetic fields are becoming increasingly popular as outdoor recreational fields, usually replacing grass fields.

In cities they are also becoming popular as playground surfaces, instead of the old “asphalt jungle” pavements. Concerned individuals from many different quarters, including environmental scientists and park advocates, health researchers, parents and community groups, are raising many questions about the potential environmental and health consequences of unmitigated synthetic turf usage.

A good summary article can be found in the March 2008 issue of Environmental Health Perspectives .  Among the main health concerns is the fact that a large component of the synthetic field is made of crumb rubber pellets derived from recycled vehicle tires. 

 Tires contain a number of known chemical toxins that prevent them from being placed even in landfills. Ground-up tire pellets are therefore even more worrisome as they tend to erode even faster and leach into groundwater. Parents are naturally concerned when they see their children in direct contact with the crumb on the fields, possibly ingesting it and bringing it home on their clothing and shoes.

To make matters worse, I and other scientists have recently been reporting how hot these playing surfaces are on summer days. A graph of synthetic turf temperatures I measured last summer, compared to a nearby grass field, is shown at the end of this blog. I often find that synthetic turf fields run 60° F hotter than grass fields on sunny afternoons, easily reaching temperatures of 140° F or more. This is close to the temperatures I have recorded on black ‘tar beach’ rooftops. So, when children play on synthetic turf fields in the summer heat, it may be like sending them to play on a rooftop surface.People enjoy the late afternoon sun in the city park of the northern German city of Hamburg April 29, 2007. REUTERS/Morris Mac Matzen (GERMANY)

Which brings me to the interesting science question: Since synthetic turf fields look like grass fields and have a similar dark-green color, how do grass fields and plants in general manage to avoid reaching such high temperatures and dying as a result?

 The answer is evaporation of soil moisture through their leaves. Plants are nature’s “geniuses” when it comes to evaporating water to stay cool in the sunlight. They need sunlight for photosynthesis of course so they perfected mechanisms of evaporation to avoid burning up. So what can plants do for those burning hot tar beach roofs? The answer is “a lot” in the form of “green roofs”, which I’ll post about next time.

 grass vs artificial temps

Graph showing surface temperatures over time: Ambient air temperature 78 F on July 3, 2007, at 1:00 p.m. The blue line, starting at just above 140 F, is the temperature for artificial turf and the lower green line, starting at 90F, is grass. Temperatures in Fahrenheit (vertical scale), time (30 minutes) (horizontal)


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Our community wants to install up to 6 of these horrible fields. Children’s sports clubs and school districts see syn turf as the holy grail of extended play. I’d like to see how the kids extend play on a warm spring day when the fields reach 140 degrees. They’ll be begging for grass.

San Francisco has a task force looking into this issue.

here are a couple of YouTube videos on the subject;

http://www.youtube.com/watch?v=8zsodulEm z0&feature=related

http://www.youtube.com/watch?v=sz3laIdWu t4

San Francisco’s City Fields – http://sfparks.googlepages.com/home

Best Wishes,

Posted by SFParks | Report as abusive

Artificial turf composition has changes with the times. There is now artificial turf material that bends like the real thing allowing an athlete to slide on artificial turf just like the real thing.