Week of 3/2/2008

Dear EarthTalk: I just read an article that said air fresheners contain chemicals that can cause health problems when inhaled. Are scented candles any better?

—Leanne Chacksfield, Cincinnati, OH

Like most air fresheners, many scented candles contain and release phthalates, potentially harmful chemicals that have been linked to the disruption of hormonal systems and other health problems in people exposed to them. Burning candles can also emit small amounts of acetaldehyde, formaldehyde and naphthalene, organic chemicals that are also potentially harmful and that can leave nasty black soot deposits on floors and other surfaces.

According to Pamela Lundquist of the nonprofit Children"s Health Environmental Coalition (CHEC), this black soot deposit "is primarily made up of elemental carbon, but may also contain phthalates and volatile organic compounds like benzene and toluene, which can cause cancer and neurological damage."

Children can easily ingest these chemicals if their hands have been wandering and end up in their mouths. The chemicals can lodge deep in the lungs, disrupting the lower respiratory tract, exacerbating existing problems like asthma, and potentially causing other longer term breathing problems.

Many scented candles release phthalates, potentially harmful chemicals linked to the disruption of hormonal systems and other human health problems. Healthier alternatives include candles made from soy, plant waste, beeswax or pure plant essential oils. Avoid paraffin candles and those using synthetic chemicals with unintelligible names.© Martoons, courtesy Flickr

Despite laws against it, many candlewicks still contain lead, long linked to impaired learning and brain damage in children. Lead dispersed from burning candles can be breathed in and also constitute part of the dreaded black soot deposit. Candles with lead-containing wicks are on the U.S. Consumer Product Safety Commission ban/recall list now (thanks to efforts by nonprofits like U.S. Public Interest Research Group (PIRG), but many are still out there on store shelves. Consumers can avoid them by sticking to candles with soft cotton wicks, not stiff, metal ones.

Eco-conscious candle burners should also avoid paraffin-based candles, which are made from waxes derived in the process of refining crude oil and literally consist of fossil-fuel generating hydrocarbons. Unfortunately, the vast majority of commercially available candles are made from paraffin, though many alternatives are now available.

Soy-based candles are a popular choice, as they are made from plant waste and emit less soot than the paraffin variety. Beeswax candles are another nice alternative, as well, especially if you can pick them up at a local farmers" market. For scented or aromatherapy candles, look for varieties that use only pure plant essential oils instead of synthetic chemicals with unintelligible names. Some leader makers of Earth- and people-friendly candles include Blue Corn Naturals, Honeyflow Farm, Vermont Soy Candles and Aveda.

CONTACTS: Children"s Health Environmental Coalition (CHEC); Blue Corn Naturals; Honeyflow Farm; Vermont Soy Candles; Aveda

Dear EarthTalk: I notice occasional solar panels on roadsides, powering individual streetlamps or signs. Is any research being done to expand on this idea and implant solar collectors in roads, parking lots or sidewalks to generate power in a similar but bigger way?

—Emily Eidenier, via e-mail

A roadside solar-powered sign in Houston, Texas. Civil engineers are working on ways to embed solar collectors in road surfaces themselves, to provide power for de-icing roads in winter and to supply current to local buildings. Caltech solar energy expert Nate Lewis says that covering just 1.7 percent of continental U.S. land surface with photovoltaic solar collectors could produce enough power to meet the nation's total electricity demand© Zelda Go Wild, courtesy Flickr.

The concept of using road surfaces to generate clean solar power is actually already moving beyond the idea stage. Roads absorb heat from the sun every day and are usually free of sightline obstructions that could otherwise block the transmission of light rays. And if the roads built for cars and driving are partly to blame for global warming, why not make them part of the solution too?

Idaho-based company Solar Roadways is one of the trailblazers. Electrical engineer Scott Brusaw was inspired to start the company when he learned that covering just 1.7 percent of continental U.S. land surface with photovoltaic solar collectors could produce enough power to meet the nation"s total energy demand.

Brusaw put two and two together when he realized that the interstate highway system already covers about that much of the nation"s land surface, so he got to work designing a system that combines a durable and translucent glass road surface with photovoltaic solar collectors that could be wired directly into the electricity grid. Brusaw"s innovative design would also heat the roads in winter, thus providing a important safety benefit.

With improvements in the efficiency of solar collectors in recent years, Brusaw believes his system, if implemented from coast-to-coast in place of the tarmac on existing highways, could produce enough energy to meet the entire world"s electricity needs.

But skeptics wonder whether such an expensive high-tech road surface can stand up to the rigors of everyday use—from overloaded 18-wheelers putting extra stress on the highway to oil spills seeping into expensive electronic circuitry—without having to be replaced or repaired often. Brusaw acknowledges that his system still needs fine-tuning, but he’d like to pave a 45-mile stretch of road between the Idaho cities of Coeur D"Alene and Sandpoint as a beta site for his system. “Testing [the project] an hour from the Canadian border,” says Brusaw, “will show the world that it will work anywhere.” He estimates it will be another year or two before his company has permission to install the Solar Road Panels on any public roads.

Europeans are also pioneering ways to use the sun"s rays to work as they beat down on roadways. The British firm Astucia has developed a road stud that contains small solar panels and emits LED light to illuminate dark roadways. On the 120 U.K. roads where the new studs have been installed, night-time accidents are down some 70 percent.

And the Dutch firm Ooms Avenhorn Holding BV has developed a way to siphon solar heat from asphalt road surfaces and use it to de-ice roads and help power nearby buildings. A latticework of pipes under the road surface allows water to heat up during warm weather. The water is then pumped deep under ground where it maintains its higher temperatures and can be retrieved months later to keep road surfaces ice-free during winter months. Apartment buildings, industrial parks and an air force base have benefited from the innovation, and the firm is working on exporting its system to other countries in the coming years.

CONTACTS: Solar Roadways; Astucia; Ooms Avenhorn Holding BV

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