Mindy Pennybacker, environmental expert and author of "Do One Green Thing," answers reader questions about making sustainable, eco-friendly home and lifestyle choices on the following slides. Check back each month for new advice, or ask a question by emailing ask-mindy@marthastewart.com.

(Please include your first and last name, city, and state. Your question may appear in a future issue of Whole Living magazine.)

Q: Which bedding is more environmentally friendly: organic cotton or bamboo fiber?

A: Organic cotton, cultivated without synthetic pesticides or fertilizers, is greener. Bamboo, organic or not, is a tough, woody grass that is often processed with harsh and polluting chemicals in order to make silky rayon fabric. The Federal Trade Commission recently ruled that, because rayon made from bamboo bears none of the genetic markers of the original plant, it must be labeled "rayon made from bamboo." However, it's worth noting that bamboo is a fastgrowing and renewable grass that thrives without pesticides, fertilizer, or intensive irrigation. When purchasing bed linens, look for USDA certified organic cotton and bamboo or their international equivalents: International Federation of Organic Agriculture Movements (IFOAM) or Quality Assurance International (QAI) certified organic.

Q: What's the difference between organic and biodynamic wine?

A: I think of the two as fraternal, not identical, twins. Here's how they're similar: Both organic and biodynamic wines use grapes grown without synthetic pesticides and fertilizers or bioengineered seeds. To be labeled biodynamic, a wine must adhere to an additional set of rules. Under biodynamic standards, first developed by Austrian philosopher Rudolf Steiner in 1924, farms must recycle and compost, employ crop rotation, and protect and respect natural ecosystems and wildlife; chlorine and fluoride must be filtered from any water used to wash grapes or make the wine itself. Biodynamic farming also incorporates a few mystical practices that may leave you scratching your head, such as burying a cow horn filled with manure, and planting and harvesting according to phases of the sun and moon. The farms and products are certified by the Demeter Association, in much the same way that organic products are certified by the USDA. If you want to drink "green" wine, the ideal is a bottle that's both biodynamic and organic. For a list of top choices and where to find them, go to greenerpenny.com.

Q: Is there a natural way to clean your oven? 

A: Conventional oven cleaner and other degreasers are among the most toxic household products around, according to the Washington Toxics Coalition. I never use anything but a homemade paste: Mix 2 cups baking soda, 1 cup washing soda (found in laundry aisles), 1 teaspoon dish soap, and 1 tablespoon white vinegar. (You can thin it with a bit of water if necessary.) Wearing gloves -- I prefer heavy cotton to plastic -- scour the oven's interior with a scrubber, rag, and hot water to remove crust that hasn't yet stuck solid. Apply thickly to all sides of the oven and leave overnight. In the morning, put gloves on and scrub, wiping with a wet cloth until all traces are gone.

Q: How can I find knitting wool that's processed and dyed in environmentally sound ways? 

A: A certified humane or USDA organic raw wool label means the sheep were raised sustainably and humanely, but it doesn't cover the processing of the wool. If the yarn itself is labeled GOTS (Global Organic Textile Standard), then it was processed with low-impact chemicals. Look for one of three types of dyes: Oeko-Tex certified are free of lead; fiber- reactive won't run off in wastewater; and cold patch dyes use less energy, water, and chemicals. Purchase organic yarns from O-wool or the Green Mountain Spinnery, or find local shops through knitmap.com.

Q: Is it better to shut my computer down or put it in sleep mode overnight? 

A: While sleep mode reduces energy drain by 70 percent, using none is even better -- and so the U.S. Department of Energy advises turning your computer off if you're not going to be using it for 2 hours or more.  Do make sure it's plugged into a power strip and switch this off to prevent phantom energy drain from the socket. Or better still, use a smart power strip, which registers your absence and turns itself off.

Q: Do biodegradable trash bags actually make a difference in the landfill? 

A: Alas, while the idea of biodegradability is enormously appealing, all these bags are likely to do is add bulk to the pile. The typical landfill, whose compacted contents never get sunlight and oxygen, cannot support the bacteria that do the biodegrading. While manufacturers claim their plant-based, bioplastic bags will biodegrade in 45 days when composted, trying this in your backyard will only disappoint. 

A 2010 test placed five brands of bioplastic bags in compost piles for 180 days and found that, while one did turn a rotten brown, four did not change at all. Bioplastic composting requires an industrial composter that reaches 140 degrees Fahrenheit. 

Still, whether or not your town is one of the few that composts them, bioplastics are a greener option than conventional trash bags because they're made from renewable resources rather than fossil fuels. (Make sure your bags bear the BPI compostable label.)

Q: I work in an office with new particle-board furniture. Is there anything I can do to make the air around my desk a little greener? 

A: Poor you! I can relate, having suffered watery eyes and asthma from a new particle-board office desk and bookshelves. The glues used in most pressed woods release VOCs, including formaldehyde, a respiratory irritant that the EPA reports is likely a human carcinogen. 

Ventilation will help disperse the fumes. Open windows if you can, make sure central air vents are working, and get a small fan to keep air circulating. You might also do a quick inventory of your work space for other potential contaminants: Keep surfaces as dust-free as possible with a rinsable, reusable cloth; dust is not only an allergen and irritant, but it can bind with toxic VOCs that evaporate from plastic computer casings as well as particle board. 

Watch out for inks and solvents, especially if your desk is near a printer, photocopier, or white board. Keep these offenders behind a closed door if you can, or ask for a fan to direct smelly fumes away from you. And bring in potted plants, which help green a space in more ways than one. Plants produce oxygen and, some studies show, absorb toxic vapors as well as carbon dioxide. Plus, they're pretty and will cheer up your office.

Q: Can I recycle scratched CDs and DVDs somehow? 

A: Yes, but first, see if you can smooth those light scratches. Apply toothpaste to the center of the disk and wipe gently, in a circular motion, out to the edges. A mild abrasive, toothpaste can also remove tarnish from silver and other metals. Rinse your disk and dry by air or with a soft lint-free cloth. 

If that doesn't work, you can recycle CDs and DVDs at Best Buy and some hardware and specialty stores and recycling centers. Certain cities will also take them in curbside recycling: Check with your municipal solid waste department. To find the options in your zip code, go to Earth911.org.

Shown here: You can also use CD cases -- and the CDs themselves -- to create cards or packaging for monetary gifts!

Q: How important is low-VOC paint? Don't the VOCs go away after it dries? 

A: Low- or no-VOC paint is very important for achieving cleaner air, indoors and out. The VOCs (volatile organic compounds) that evaporate from regular paint can include some nasty respiratory irritants, nervous-system toxicants and chemicals linked to cancer. Tests conducted by the EPA found these gases can migrate out of latex paint for more than six months.

Q: Mom always told me cooking with aluminum foil will result in chemicals leaching into my food. Is that true? 

A: Mom was probably thinking about the Alzheimer scare a few decades back, in which aluminum cookware was suspected of contributing to the onset of dementia. Aluminum was released from culpability on that score once all the studies were in, but, according to Dr. Janet Gray of the Breast Cancer Fund, aluminum can mimic estrogen and, although there as yet are no studies that make the connection, a possible risk factor for breast cancer. 

The U.S. Centers for Disease Control has a long list of the possible toxic properties of aluminum, none of which have been conclusively proven, but still ... 

For intensive daily cooking, you might prefer to use pots and pans made of glass, cast iron, stainless steel or anodized aluminum, which will not leach toxins or toxic chemicals into food. But one can't beat the convenience of lightweight foil in a toaster oven or as a cover for a roast or pie, and I wouldn't worry, because it's not as if you're really cooking in it. Do wash, reuse or recycle foil, though, if it's not too stuck- or gunked-up, because the extraction of aluminum from bauxite ore is environmentally damaging.

Q: Set the record straight once and for all: Is taking a bath better for the planet than taking a shower?

A: As much as I love a good soak in the tub, I have to admit that it's a bigger drain on the earth. A typical bath takes 30 to 70 gallons of water, according to the EPA, while the average eight-minute shower uses only 17 gallons, reports the Alliance for Water Efficiency. A bath also uses more fuel to heat water, which means more pollution and greenhouse-gas emissions from the power plant that supplies your home. 

I find a five-minute wash under a low-flow showerhead gets me squeaky clean with only 12.5 gallons and no sense of deprivation (well, almost!). The reward: You've earned the occasional indulgence of a good, long bath.

Q: I just learned I have lead paint. What do I do?

A: Although lead-based paint was banned in 1978 because the neurotoxic metal can damage children's developing brains,  more than half of U.S. homes still contain it, according to the U.S Environmental Protection Agency (EPA). 

Don't try to remove lead paint yourself.  Note its condition: If the paint is  flaking, peeling, or creating dust, it can easily be eaten or inhaled. Don't vacuum it! Whether you're spring-cleaning or starting a renovation, use a licensed lead abatement specialist and keep yourself and your family away until the work is finished and thoroughly cleaned up.

Happily, EPA regulations implemented in April, 2010 require all contractors working on renovations and repairs of pre-1978 homes to be certified for lead paint removal. To find one, and get more lead safety tips, go to EPA.gov/lead or call the National Lead Information Center Hotline and Clearinghouse for a free pamphlet: 1-800-424-5323.

Q: I'm moving soon. How can I make the process less wasteful? 

A: Reuse clean sturdy cardboard boxes and packing materials you collect from local stores; in many towns, you can also rent boxes from green moving companies, such as Rentagreenbox.com's "recopacks" made of recycled plastic. As you organize and pack, set unwanted kitchenware and electronics, furniture, books and clothes aside for a yard sale and/or to donate to local charitable thrift stores, the Salvation Army or Goodwill. Where possible, close boxes without strapping tape, by folding flaps or using hemp twine. Remember to use water-based markers to cut down on fumes! 

To transport your worldly goods, and yourself, long distances, choosing ground rather than air will save up to half the carbon emissions as well as money. Rail has the lightest carbon footprint; for more info see FreightCenter.com. If you'd rather drive yourself or hire movers, see if there's a local moving company that uses trucks that burn biodiesel made from cooking oil. Search the national database and get cost quotes from GreenMoversUSA.com.

Q: Can I recycle my old sneakers somewhere?

A: Absolutely. You can extend the life of wearable old shoes by donating them to non-profits that give footware to the needy all over the world. See a list of organizations at eco-officiency.com. 

If your sneakers have plumb run out of juice, Nike's Reuse-a-Shoe program accepts all brands of athletic shoes and has repurposed millions of pairs into sports surfaces for playgrounds, running tracks, and basketball courts. 

Q: How can I reduce the amount of junk mail I get?

A: Stopping the deluge is free and easy through Catalog Choice. On their site, you search for participating companies (they're almost all there!) and check them off. It can take up to three months to fully take effect, but trust me, it works. Another free -- and often faster -- option is to call companies on the toll-free customer service phone number in the catalog. 

To remove your name from junk-mail lists, use the Direct Mail Association's online service. It costs only $1. Or, subscribe to Precycle (formerly Green Dimes). For $36 a year, they'll declutter your mailbox and plant five trees on your behalf.

Q: Can you recycle bottle caps along with bottles?

A: Actually, we must keep bottle caps out of the recycling bin. Not only are they not recyclable in most cities, but it turns out these little nuggets can really gum up the works at the recycling plant.

They're generally made of a different plastic resin -- Polypropylene (PP) #5 -- which has a much higher melting point than the bottles, which are mostly Polyethylene (PET) #1. The unmelted caps in a vat of liquid PET can ruin the whole batch, not to mention clog the machines. 

What to do with these pesky PP toppers? Drop them off at the nearest Aveda store for recycling, or mail them to the Recap Company in Ohio.

Q: How am I supposed to dispose of old paint?

A: Carefully! Paint is classified as household hazardous waste (HHW), so be mindful of your safety and the planet's. Never pour paint down house drains or storm gutters, or chuck cans of liquid paint into the trash. Not only can this get you arrested in some cities, but toxic chemicals in paint can pollute waterways and the fumes readily contaminate the air we breathe. 

When buying new paint, choose those labeled no- or low-VOC, which means that volatile organic compounds have been kept to a minimum. If old paint has totally dried into a solid mass (check this by holding can upside down, or pushing a screwdriver through to the bottom) you can legally put it in the trash bin in some states -- but this is not the green way, since it will add to solid waste in a landfill. 

The greenest choice is to get paint into the hands of public agencies that can recycle or safely dispose of it. Check with your municipal solid waste department about HHW collection days, when and if you can take paint to a drop-off site. Sometimes, if you're lucky, there are scheduled pick-ups from homes! Be sure not to combine latex (water-based) and enamel (oil-based) paints, since they have to be recycled separately. 

For more detailed information about recycling paint, call 1-800-clean-up or see the Earth911 paintwise portal.  For more on household hazardous waste, see the EPA's web page.

Q: I've heard that throwing away some glass is actually good because it helps break down other trash in the landfill. Is that true?

A: No. Honestly, the tons of trash in landfills are usually so tightly packed that there's no oxygen available to enable decomposition. Glass is inert, which means it doesn't react with other substances, so it's one of the rare materials that can be recycled over and over without any loss of quality. Dumping it in the landfill would be an unconscionable waste of the energy and natural resources used to produce it, says Susan Collins, executive director of the Container Recycling Institute.

Q: What's the most eco-friendly way to get rid of a mattress? 

A: You could try donating it to a local charity, but often health departments won't allow it. Try giving it away on Craigslist.org or Freecycle.org. Or search Earth911.org to see if there's a center near you that can recycle the steel and the fiber inside the mattress.

Q: Are there any no-energy ways I can keep my home cool this summer?

A: My favorite way to stay cool is by putting my feet up and living easy with some lemonade. Oh, and reading by daylight rather than watching TV, since electronics and lightbulbs release heat in addition to using energy. 

You can also plug computers, televisions, and appliances into power strips and turn them off when you're not using them, and plug your cell phone, MP3 player, or camera into a solar charger. Shade sunny windows with awnings, and cover them with curtains, shades, or blinds. (Visit energysavers.gov for tips.) 

Finally, cover windowpanes with low-e (low-emissivity) films to reduce unwanted solar heat; visit snaptint.com and buildinggreen.com for examples. 

Q: How can I unclog a drain without loads of toxins?

A: A clogged drain is bad enough -- why add injury to insult? Conventional drain cleaners contain toxic chemicals such as sodium hydroxide, the active ingredient in chlorine bleach. The fumes can cause breathing difficulty and nausea; the product can burn your skin. Furthermore, drain cleaners can react with ammonia, another common ingredient in household cleaners, to produce a form of chlorine gas, used as a chemical weapon in the first world war. Finally, their corrosive action can damage pipes.

To tackle a clog without these chemicals, you'll want to try a combination of boiling water, vinegar, and baking soda. You may also need a wire coat hanger or a plumber's snake, or a greener enzyme drain cleaner.

Q: What's that funny smell in my new couch, and how can I get rid of it?

A: You are wise to be concerned: That funny smell may be no laughing matter! Chemicals in some sofas can actually cause dizziness and fainting and have been linked to nervous system harm in developing children. These smelly vapors come from volatile organic compounds (VOCs), which readily evaporate, or "offgas," polluting your indoor air. And they're at their peak outflow when products are new.

But there's no reason to panic and shun your new couch! Instead, reduce your exposure while gradually getting rid of the smell by washing removable cushions and ventilating the couch by opening windows and/or running a fan.

Q: What's an eco-friendly dry cleaner? Should I be using one?

A: The best eco-friendly dry cleaners use green alternatives to the standard highly toxic cleaning solvent known as perchloroethene, or "perc." Perc fumes cause that cloying, sweet dry cleaning smell. Symptoms of perc exposure can include dizziness, headache, nausea, and skin and lung irritation, according to the U.S. Environmental Protection Agency. The International Agency for Research on Cancer lists perc as a "probable human carcinogen." In short, perc's bad stuff and should be avoided as much as possible, even if it means washing delicates in cold water at home.

If you need to send your clothes out, look for a professional cleaning shop that uses an alternative method, such as "wet cleaning" or liquid CO2.

Q: Can clothes really get clean in cold water?

A: Yes, really! Cold water will clean your laundry as well as hot most of the time. Plus your laundry area will be cooler, and you'll use 90 percent less energy.

But there are exceptions. Unsanitary items, such as diapers, should be cleaned in hot water; so should bedding, to kill allergenic dust mites. For other heavily soiled items, try warm water; it still saves energy compared with hot.

Q: Do I need to wash out my bottles and containers before putting them in the recycle bins?

A: Yes, but gently: Think degunked rather than pristine clean. Plastics, glass, and cans will be sorted, cleaned, and broken down at the recycling center. All we need to do is prep them for their journey, the way we scrape dishes before loading them into the dishwasher.

Q: How do I prevent bacterial growth in reusable water bottles?

A: Once a day, wash your reusable bottle and cap with hot water and dish soap, either by hand or in the dishwasher (though keep in mind that high heat can break down plastics over time). I prefer to scrub the interior using a Rubbermaid bottle brush made of nonleaching polypropylene (#5) plastic (or try a natural German boar brush, available for $5 at kitchenworksinc.com). Let it air-dry completely to discourage the growth of bacteria, which thrive in moist environments.

If scungy spots persist, add one part white vinegar, lemon juice, or hydrogen peroxide, all mild disinfectants, to four parts warm water and shake well, then let stand for a couple of hours before rinsing. Don't use chlorine bleach -- it poses real danger to you and to aquatic life and can contaminate drinking water with carcinogenic trihalomethanes. And never, ever microwave plastic to clean it! It's ineffective -- plus, even non-polycarbonate containers, when heated, can leach the chemical bisphenol-A, which has been linked to diabetes and cardiovascular disease. For a list of better bottles, visit greenerpenny.com/guides.

Q: Is it better to buy a product in a recycled plastic bottle or a glass bottle?

A: For a drink or food (especially if it's acidic), I'd choose glass, which is infinitely recyclable. Eighty percent of glass containers that are recycled are made into new ones -- and glass is free of phthalates and bisphenol-A that can leach from plastic. However, you might not want to use breakable glass around children. And even though plastic is made of fossil fuels, its light weight requires fewer fossil fuels in shipping than glass. Just be sure to choose plastic marked "post-consumer recycled" (PCR) or "post-consumer waste" (PCW). Regular "recycled" plastic is usually made from factory scraps, which only encourages the continued production of new plastic.

Q: How can I brighten my whites without using bleach?

A: So glad you asked -- chlorine bleach is highly caustic (which means it can burn our skin, eyes, and respiratory tract), harms aquatic life, and reacts with organic matter to produce toxic compounds called trihalomethanes in our drinking water. You can use a chlorine-free commercial bleach based on hydrogen peroxide or oxygen, or DIY it with some old-fashioned basic ingredients.

Q: I have to ship a lot of holiday presents to my family. How can I do it less wastefully?

A: The best thing is to order and send gifts early, ideally at least six weeks in advance. Last-minute air delivery burns more fossil fuels than boats or trucks and releases the most global-warming CO2. A better choice is a lightweight gift or one that requires no shipping at all (such as theater, concert, or sports tickets held at a will-call window). It can also be greener to buy in your gift recipients' locales. As you make your list, ask your far-flung family members about their favorite stores and order from there (which also makes returns simpler). If several recipients live in the same town, send a batch of gifts from the same merchant, which saves on fuel miles. Finally, when you order, forgo gift boxes and ask retailers to minimize packaging and use recycled materials.

Q: Is it bad to use wrapping paper as fireplace kindling?

A: You've got the right idea to reuse wrapping paper rather than tossing it in the trash. An additional five million tons of waste -- including four million tons of paper -- is generated in the U.S. every holiday. However, destroying reusable paper is less green than saving it to wrap other gifts, make greeting cards, or use as scrap paper. Burning it is also unhealthy: Fireplaces are a leading source of lung-clogging particulate air pollution and toxic carbon monoxide. The inks and metals in conventional gift papers may contain heavy metals, such as lead and cadmium, that are unhealthy to send up in smoke.

Mindy Pennybacker is author of "Do One Green Thing" and editor of GreenerPenny.com. Do you have a question about green living and making sustainable choices? Email ask-mindy@marthastewart.com and your question may be answered online or in a future issue of Whole Living. Please include your first and last name, city, and state.

Check back every month for new advice from Mindy, and visit her blog at Whole Living Daily.