Leave Your Shoes At The Door

Question: My sister always insists that we take our shoes off at the door. She says that it is cleaner and safer. I think that it is an old wives tale. Is there any data to support her claim?

Response: In the olden days (as my kids call them), taking your shoes off at the door was the norm. This custom is still the standard practice in Korea, Japan, and many other countries. Even in countries where shoes are generally worn indoors, related practices are followed, as door mats are often placed at entryways for people to wipe their feet before entry.

These "shoe off" and "door mat" practices came about to reduce the amount of dirt that gets tracked into your home. Shoes clearly can be a source of substantial dirt, as is evident from the footprints left when you walk in shoes on a clean, wet floor. Not only can shoes bring dirt into your home, but they can also bring pesticides, lead, and other chemicals that can be present in dirt. The U.S. Environmental Protection Agency (EPA), for example, showed that people bring lawn pesticides into their homes on their shoes. These pesticide-laden shoes were a major source of pesticide exposures, especially for young children who spend a lot of time on the floor and who put dirty fingers, dust, and toys in their mouths. Somewhat surprising was that the study showed that indoor shoe-wearing was a larger source of children’s pesticide exposures than eating non-organic fruits and vegetables. Taking your shoes off and wiping your feet on a door mat or other carpeting before entering were found to be important pollutant reduction measures.

Even if you do not use pesticides on your lawn or have lead in your soil, you can still have pesticides, lead and other chemicals on your shoes from your travels to other lawns and other places. These pesticides and chemicals can stay on your shoes for quite some time. So, it clearly makes sense to listen to your sister (at least in this one case) and take your shoes off before you enter your home. For added insurance, you can put a door mat just inside your door to store the shoes or to have people wipe their feet before coming inside. Your home will not only be cleaner, but may also look better, especially if you chose a nice looking door mat.

Don’’t Eat Yellow Snow…or Black…or Brown…or Pink…

Question:My kids always want to eat snow. If I can help it, I don’t let them, but I can’t watch them all the time. It’s driving me crazy. What do you think?

Response:
If the snow is yellow, black, brown, pink or otherwise dirty, it should not be eaten, as the colors each point out the presence of a different kind of pollution – yellow pollution from animals, black and brown pollution from dirt, cars, and people, and pink from bacterial contamination. The snow can collect these pollutants once it falls to the ground by being stepped on, splashed on, or otherwise having pollution fall on it. More surprisingly, perhaps, snow can also become contaminated by pollution as it falls to the ground.

It turns out that snow is a fairly efficient pollution collector when it is in the air. Snow is formed by water vapor that moves in clouds in cold air. As the water vapor moves in the cold air, it can stick to a tiny piece of dust and then have other water molecules attach to it, forming a crystal. Once formed, the crystal can continue to grow and can stay in the air for hours before it falls to the ground. It is during this time that the snow crystal can collect or “scavenge” pollutants that are present in the air. As a result of this scavenging, snow can contain all kinds of airborne pollution, even if it is white and freshly fallen. They types of pollution that the snow can contain vary by location, but could include metals, acidic pollutants, and persistent organic pollutants (POPs). The amount of pollution in white, fresh snow is generally very low in rural areas and is higher in cities and other areas with a lot of traffic, since traffic is known to be a major air pollution source.

Even so, should you be worried? For white, freshly fallen snow, probably not, given that scientific studies show low amounts of pollution in fresh snow and given that kids generally don’t eat much snow. But for colored snow and for snow that has been sitting on the ground for a while, it is definitely best for your kids to look and not eat. A good way to show them why may be to melt some snow in a container and see what you find. Almost always, you will find dirt, sticks and other debris that were previously hidden.

Does an Organic Diet Matter?

Question: I only buy organic foods for my family, even though it is more expensive. I’ve always assumed that this reduces my family’s exposure to pesticides, but recently read in the news that this isn’t true. Does it?

Response: Yes, with qualifications.

Organic foods are essentially free of pesticides, while nearly every type of conventional fruit and vegetable has at least one type of pesticide applied to it sometime from when the seeds are put into the ground to when they are sold. Logically then, eating organic foods rather than conventional foods will reduce your family’s exposure to pesticides.

The qualifications relate to the amount and importance of that reduced exposure.

The amount of the reduction in pesticide exposures will, of course, depend on what your family eats. The best scientific studies of pesticide exposures from foods suggest that an organic diet will basically eliminate one microgram of pesticides that would otherwise be eaten on a conventional diet in a typical day. [Putting this microgram into perspective is difficult, but for what it’s worth, a person eating 1,800 calories a day will typically eat 70 grams (or 70,000,000 micrograms) of fat, while a wasp sting delivers about 2 micrograms of venom. Of course, these comparisons say nothing about their dangers, as the toxicity of the pesticides differs tremendously from that of the fat and venom.]

The impact of switching to an organic diet is illustrated by a Seattle, Washington study, in which 23 children ate non-organic foods on the first three days and last seven days of the study. On the days in between, the children ate organic fruits and vegetables in addition to conventional meat and dairy products. During the first and third stages of the study, every one of the children had measurable amounts of pesticide metabolites (which are the less toxic break-down products of pesticides) in their urine. During the second organic fruit and vegetable stage, the amount of metabolites for two common pesticides chlorpyrifos and malathion was about ten times lower than the conventional diet periods.



Whether these lower levels translate into less health risks is not known, since pesticide metabolite levels during both the organic and non-organic diet periods were lower than US EPA limits. Also, these lower levels do not consider pesticide exposures that occur through the air, soil, indoor dust and water. Although its contribution varies by pesticide and by person, for the average person, food is only a minor contributor to exposures many common pesticides, including chlorpyrifos (used mostly on cotton, corn, almonds, and orange and apple fruit trees) and permethrin (used mostly on cotton, wheat, corn, alfalfa, and poultry). For example, in one scientific study, food accounted for only a few percent of total exposure to chlorpyrifos, while breathing indoor air contributed more than 80%. As a result, it is quite possible that a diet of organic foods will have only a modest effect on total exposure to pesticides.

That said, a growing number of scientific studies have shown that exposures to even small amounts of pesticides are harmful, especially to young children – which I think provides a pretty persuasive reason for you to keep buying organic food. A steady organic food diet is a good and relatively easy way (costs notwithstanding) to lower your risks from pesticides.

Is Aluminum Cookware Bad for You?

Question:
I have a question about aluminum. I know the health risk aluminum can create for the body if one takes in too much as well as it's link to Alzheimers disease. I know that aluminum cookware, cans, and that antiperspirant can pose health risks. My question is about aluminum "cookware". I've heard cooking acidic foods in aluminum cookware can cause the aluminum to leach out of the pan so I've avoided them. However, I've found a high quality cast aluminum manual juicer by Ra Chand and I'm wondering if this all aluminum juicer will pose a significant risk to my health. Do you think the risk to my health will be high if I use it daily to squeeze oranges and other citrus fruits-especially because of their acidity? Could they cause enough leaching of aluminum for it to be a health risk? Or does the aluminum have to be exposed for a relative time period to the citrus for leaching to occur. What would you recommend?

Response:
Aluminum, a soft metal, is found nearly everywhere in the environment. Most exposures to aluminum occur through ingestion or eating and drinking, with daily intakes generally low, averaging between 30-50 mg. For the typical person, drinking water, medicines and other pharmaceuticals (such as antacids and antiperspirants) are the biggest contributors to aluminum exposures; however, aluminum cookware is also a potential source. As you note, aluminum exposures have raised some health concerns due to the effects of aluminum on the human nervous system and the much discussed (but inconclusive) linkages between aluminum exposures and Alzheimer's disease.

Aluminum exposures from cookware, of which more than half is made of aluminum, is not well studied, but is thought to be a relatively minor source of aluminum exposures. Exposures to aluminum through food can occur when aluminum leaches or otherwise dissolves from the cookware into the food. Leaching is most likely when the foods being cooked or stored are highly basic (like baking soda) or highly acidic (like tomato sauce, lemon juice, oranges, or vinegar). For example, tomato sauce has been shown to contain 3-6 mg aluminum (per 100 g serving) after cooking in aluminum pans, which translates into about one-tenth of the typical daily intake. This leaching of aluminum with acidic foods does not happen with aluminum cookware that is anodized, or electro-chemically processed to seal the aluminum in the cookware. Clemson University Extension’s Home and Garden Information Center tested different cookware types, and found anodized aluminum cookware to be safe. Regardless, it would probably be wise to store tomato sauce and other acidic foods in something other than an aluminum pot.

As for the juicer that you mention, I did a quick and non-exhaustive check of various websites, none of which said that the juicer is made of anodized aluminum. One site did say that it was made of acid-resistant aluminum and chrome, suggesting that the aluminum is somehow sealed and that leaching of aluminum will not occur during the juicing process. An easy way to check for this is to look at the juicer and see whether the aluminum becomes pitted or pock-marked after several uses. Since leaching takes time and juicing is a relatively quick process, this pitting would not occur immediately but would rather occur over time. As a result, you should probably continue to check your juicer for pitting over time.

Are Tattoo Inks Toxic?

Question:
I've been wanting to get myself a tattoo for a few weeks, but I've heard that tattoo inks can be toxic. Where/How can I find a tattoo artist who uses "safe" inks?

Response:
The safety of tattoo inks or pigments have recently been the subject of some attention, possibly the result of a lawsuit brought by the American Environmental Safety Institute (AESI) against Huck Spaulding Enterprises, Inc., Superior Tattoo Equipment Co., and other tattoo ink sellers in the U.S. As a result of this lawsuit, the companies must place a warning for their California customers on their tattoo ink labels, catalogs and Internet sites that reads "inks contain many heavy metals, including lead, arsenic and others" and that the ingredients have been linked to cancer and birth defects. These adverse effects have been shown for exposures that occur over long time periods to these and other heavy metals, although not explicitly from these metals in tattoos. Although the US Food and Drug Administration (FDA) has the authority to regulate tattoo pigments, tattoo pigments have not yet been approved by FDA for injection into the skin, as is done when a tattoo is made.

Heavy metals are used to give tattoo pigments their permanent color. The specific ingredients that are used in the pigments differ by color and by brand, but may include not only lead and arsenic, but also antimony, beryllium, chromium, cobalt, and nickel -- metals that have also been linked to bad outcomes in people. The amount of these metals in a tattoo may be substantial. For example, AESI states that the ink used for an index card sized (3” by 5”) tattoo contains 1.23 micrograms of lead, which is more than double the amount permitted per day under California’s Proposition 65.

Certain tattoo colors may present greater health risks than others. For example, green and blue pigments produced from copper salts (Copper Pthalocyanine) are thought to be safe, as they are approved by the U.S. Food and Drug Administration (FDA) for use in contact lenses, surgical implants, and infant furniture paint. Similarly, black pigments made from carbon black or india ink, white pigments made from zinc or titanium white, purple pigments made from dioxazine/carbazole, and brown pigments made from iron oxides are thought to be have minimal (if any) health risks. Of the colors, red pigments, especially those that contain cadmium, iron oxides or mercury (cinnabar), are generally the most worrisome. Mercury in tattoo pigments, for example, has caused allergic reactions and scarring in people and has sensitized people to mercury from other sources, such as fish or dental fillings.

In light of these and other concerns, it makes sense to think twice about getting a tattoo. At a minimum, you should find out the ingredients of any tattoo pigments that will make up your new tattoo. This information may be hard to find, since the ingredients of tattoo pigments are considered to be proprietary and thus are usually not listed or otherwise revealed. Some tattoo artists, however, do mix their own tattoo pigments, in which case they should be able to tell you the ingredients. I would suggest going to only those artists that can give you this information.

Microwave Popcorn and the Kernel of Truth

Question:
For the past several years, I have been eating a bag of microwave popcorn almost every day. I just read that this can damage my lungs. Is this true? Should I be worried?

Answer:
Microwave popcorn has been around for more than 50 years, since the invention of microwave ovens. Microwave popcorn is relatively easy to make at home using popcorn, a brown bag, some staples (yes, staples!) and other ingredients, such as salt and butter. More commonly, people make popcorn in their microwave using ready-made microwave popcorn packages, many of which contain additional chemical ingredients. The chemicals that are used to give microwave popcorn its buttery flavor are the reason why microwave popcorn has been in the news recently.

In particular, scientific studies have linked diacetyl and other chemicals that give the popcorn its buttery flavor to lung damage in people that work in microwave popcorn factories. A study by the National Institute for Occupational Safety and Health (NIOSH), for example, showed that microwave popcorn workers were continually exposed to high levels of these buttery chemicals and that these high levels were related to a serious and permanent type of lung disease, often called "popcorn lung". These risks were shown in workers exposed every now and then to very high levels of butter-flavoring chemicals and also in workers continually exposed to lower (but still higher than normal) chemical levels. Similar findings have also been shown in other scientific studies of people and animals, providing important, supporting evidence that inhaling large amounts of butter-flavoring chemicals is dangerous to your health. These dangers to workers are well-accepted, as evidenced by the fact that just this week, the the US House of Representatives passed H.R. 2693, the Popcorn Workers Lung Disease Prevention Act.

Whether there are similar risks for the general microwave popcorn-eating public, has not been studied, but any potential risks should be limited to those eating popcorn with artificial butter flavoring. Even for these people, risks are thought to be low, since people preparing pre-packaged microwave popcorn at home are exposed to lower chemical levels and for much shorter time periods than the workers. Recently, however, health concerns were raised for people who eat a lot of pre-packaged microwave popcorn. In July 2007, a pulmonary doctor from Denver's National Jewish Medical and Research Center notified the U.S. Food and Drug Administration (FDA) of a patient who ate butter-flavored microwave popcorn several times a day for years and who now has a disease similar to "popcorn lung". As a result of this letter, FDA, the U.S. Centers for Disease Control (CDC), and the U.S. Environmental Protection Agency (EPA) are looking into the possible dangers of preparing pre-packaged microwave popcorn at home. Regardless of what they find, many makers of pre-packaged microwave popcorn have plans to stop adding diacetyl to their popcorn.

Until this time, there are several things that you can do to reduce any risks and/or your worry over pre-packaged microwave popcorn. Clearly, the most foolproof solution is to make microwave popcorn that does not contain artificial butter or to stick to homemade microwave or stove top popcorn. If you do prepare butter-flavored microwave popcorn, you can limit your exposures to the buttery chemicals by venting your microwave oven to the outside, opening nearby windows when you microwave the popcorn, letting the popcorn cool before you open the bag, and opening the popcorn bag outside.

Is Eating Seaweed Dangerous?

Question:
I was wondering if you could tell me how safe eating seaweed is these days, pollution wise. I hear lots about fish, but nothing about seaweed. Our family consumes 6-12 ounces a week. We buy organic, but it's wild caught. I eat seaweed in salads, sandwiches, and sushi. Mostly we just snack on dulse. -which I believe comes from the Atlantic. And we use Kombu, kelp, when cooking soups and beans. I believe the Kombu is local. We're in Santa Cruz, Ca. Thanks so much for your time!

Response:
Edible seaweed is a marine algae that can come in many forms, including the type that you mention kombu, as well as the commonly eaten wakame and nori seaweeds. Although long part of the Asian diet, edible seaweed has increasingly become a part of Western diets due to its well-documented nutritional and often discussed medicinal qualities.

In comparison, there is little information about the possible negative effects of eating seaweed. A couple of years ago, several governments, including the Canadian and British governments, issued warnings advising people not to eat one type of seaweed – hijiki – because of concern over high levels of inorganic arsenic, a toxic element that has been linked to cancer, that was found in seaweed samples. Since little was known about the specific risks of arsenic in hijiki, hijiki was not banned. The warnings, which were intended to give the consumers a choice, explicitly stated that eating hijiki occasionally was probably not dangerous. Importantly, the warnings did not apply to other more commonly eaten seaweeds, including arame, nori, kombu, and wakame, which were found to be free of arsenic.

Based on these and other concerns, several scientific studies have been performed to measure the amount of metals present in seaweed. Results from these studies show that metal contamination of seaweed depends on three major factors, including where the seaweed was harvested, the type of seaweed, and the specific metal. For example, in a small Canadian study (Van Netten et al., Science of the Total Environment, 2000), seaweed grown in waters near British Columbia, Canada generally had lower amounts of heavy metals, especially of mercury, than seaweeds grown in Japan and Norway, possibly due to lower amounts of these metals in British Columbia waters. All seaweed samples – even those grown in Japan and Norway – however, had metal levels that are generally thought of as safe to eat.

What this means for you and your family is that you can continue to enjoy your seaweed salads, soups, and sushi (although given the governmental warnings I would probably stay away from hijiki). Given seaweed’s many nutritional benefits and relatively low pollutant levels, seaweed is probably not only a safe food but also one that is good for your health.

What is Vapor Intrusion? Should I Care?

Question:
Could you discuss the issues and health risks related to "vapor intrusion" of volatile organic chemicals into buildings from contaminated sites? What can a homeowner or purchaser do to find out if there is a vapor intrusion risk at home, schools, or day care centers?

Response:
“Vapor intrusion” (sometimes called “soil gas vapor intrusion”) is what happens when chemicals move from the ground or water into your home or other buildings. Chemicals that enter your home through the ground often belong to a class of chemicals called “volatile organic compounds” (VOCs), which as their name implies are volatile, and thus like to exist as a gas.

This property is important, allowing VOCs to move easily through openings that exist between the soil grains and thus to move from areas of high pressure to areas of low pressure. Since basements tend to be at lower pressure than the ground below, this pressure-related movement can cause VOCs to enter your home from the ground through openings or cracks in your foundation. Once inside, the VOCs can spread through out your home with the help of natural air flow, room or house fans, or other home ventilation devices. When this occurs, vapor intrusion can be an important source of indoor pollution in your home.

Whether vapor intrusion also presents additional health risks depends on many factors. For example, health risks will depend on the people that live or spend time in your home, as people have different responses to chemical exposures. Health risks will also depend on the type and amount of your chemical exposures, more precisely the specific VOCs that enter your home, their levels inside your home, and the length of time that the VOCs remain elevated.

Although other kinds of chemical spills, leaks or contamination can also lead to vapor intrusion in homes, the most common VOCs associated with vapor intrusion are gasoline-related, the result of spills or leaks from an underground storage tank at a gas station. For gasoline-related intrusions, VOCs of concern may include (but are certainly not limited to) benzene, toluene, xylenes, and styrenes. Exposures to these and other gasoline-relaed VOCs have been linked to a variety of adverse effects, including short term (and generally reversible) effects such as eye and respiratory irritation, headaches, and nausea, and long-term effects, such as cancer.

There are several ways to test if VOCs or other chemicals are entering your home through the ground. You can collect samples in the nearby ground (soil vapor samples), in the ground directly below your foundation (sub-slab vapor samples), in your indoor air, and in your outdoor air (for comparison). Samples in these different places should be collected at the same time, preferably during the heating season when the pressure difference between the ground and the basement should be highest. Similarly, indoor samples should be collected in the basement or first floor of the living space, since these are the areas in your home where the levels from vapor intrusions should be highest. Since there are many sources of VOCs inside your home and since indoor VOC concentrations can vary widely day-to-day, indoor sampling results may be more difficult to interpret than the soil and sub-slab sampling results, but interpretation of indoor sampling results will be easier with outdoor sampling data and information about your house, including its ventilation, characteristics, and other VOC sources.

Also, if you know that a nearby gas station, commercial or industrial facility or other site has had a spill or a leak of VOCs, you may want to call the owners, local government officials, or the people cleaning up the spill to see if any sampling is being performed to test for vapor intrusion and if so, to ask for testing to be performed at your home. The U.S. Environmental Protection Agency provides extensive technical guidance on vapor intrusion including “safe” levels of chemicals in groundwater and soil gas (See Draft Guidance at http://www.epa.gov/correctiveaction/eis/vapor.htm).

If tests show that chemicals are getting into your home through the ground, there are many possible solutions, including sealing cracks and openings in the foundation or installing a radon remediation system. Often, the costs of these solutions will be paid for by the person or company who allowed the chemicals to get into the ground.

Pollution from Paraffin Heaters: Is It a Problem?

Question:
I have a passive solar house that gets most of its winter heat from the sun. I have a backup woodburning masonry stove that provides heat to my living room, kitchen, dining room open space. But my bedrooms do not yet have backup heating from a renewable heating source. So for the meantime I use a small portable paraffin heater in my master bedroom-bathroom. In the cloudiest two months of the cold season (basically the rainy months) I have to use this heater most evenings for at least a few hours. I usually turn it off at midnight or so. Some days I have to leave it on all day (but not during the night). My house is fairly well ventilated. My wife and I wonder what kind of pollutants these heaters give off and how much we have to worry about it. Could you give me some advice? Thank you.

Response:
Portable paraffin (often called kerosene) heaters have been used for a long time to heat indoor spaces. Paraffin heaters produce heat by burning fuel (in this case paraffin or kerosene). Since they do not require electricity, many people find them to be an attractive supplemental heating method.

Paraffin heaters generally follow a similar design, including a fuel tank, a wick to draw kerosene from the tank to the combustion area, a device to ignite the wick, and an automatic device that puts out the wick if the heater is accidentally turned over. Most newer heaters also have additional safety features to reduce the risks that would come from improper use or maintenance.

Despite these safety precautions, paraffin heaters pose a fairly significant fire hazard. This risk of fire is greatest if gasoline instead of paraffin is used as the fuel source and if the paraffin heater is not properly maintained or operated. Many governmental agencies and fire departments believe that the risk of fire from paraffin heaters is greater than that for other portable heating devices.

Paraffin heaters also pose a risk to health. Paraffin heaters, especially those that are unvented to the outside (as would the case be with a portable heater), are a significant source of indoor air pollution Research studies, including those conducted by my colleagues, have shown that paraffin heaters emit a number of pollutants typically associated with combustion or burning, including carbon monoxide, nitrogen oxides and sulfur dioxide, as well as polycyclic aromatic hydrocarbons and phthalates, among other pollutants. Exposures to these pollutants have been linked to a variety of adverse effects, ranging from headaches to breathing difficulties to death. These effects may occur shortly after breathing in these pollutants or may occur after years of exposure. They may also occur more readily in certain susceptible people, such as the elderly, children, and people with asthma.

Your exact health risks will depend on your susceptibility and also on your exposures to the heater-associated pollutants. Your home being fairly well ventilated is in your favor, as the emissions from your paraffin heater will likely have less time to accumulate inside your room, and as a result, your room levels of -- and thus your exposures to -- heater-associated pollutants will be lower. This is why many paraffin heater manufacturers recommend that the heater only be used when a window or a door to another room is opened at the same time. One rule of thumb is to provide 1 square inch of window opening for each 1,000 BTUs of the heater rating. For example, if you have a 10,000 BTU heater, you should open an outside window 10 square inches to provide the necessary ventilation. If your home is an energy efficient home, you may need to ventilate your room even more.

Even with these and other safety precautions, I believe that the fire and health risks outweigh the convenience or other reasons for having a paraffin heater. If possible, I would recommend switching to a heater that is vented to the outside or switching to a different type of portable heater. Regardless, I would make sure to have several carbon monoxide monitors located in your bedroom and in other places in your home.

Green Dry Cleaning Alternatives

Question:
I have a number of cashmere sweaters that I love. But I know dry cleaning isn't environmentally friendly. I was hoping you could recommend a way of cleaning them that would be a little less damaging to the environment.

Response:
It is true that traditional dry cleaning methods are not “environmentally friendly”. This is because most dry cleaners use the chemical perchloroethylene (also called perc, tetrachloroethylene, C2Cl4 and Cl2C=CCl2) to clean your clothes. Research studies have shown that perchloroethylene exposures may be dangerous to your health, having been linked to increased risks of bladder, esophageal, and cervical cancer, eye, nose, throat and skin irritation, and reduced fertility, among other effects. These findings have been shown for people who work at dry cleaners, who are routinely exposed to high amounts of perchloroethylene, either through inhalation or through skin contact.

People who work in dry cleaners are not the only ones exposed to perchloroethylene. Low levels of perchloroethylene can also be present in your indoor air, as any perchloroethylene that was not removed in the dry cleaning process can come off your clothes and go into the air. Also, since dry cleaners are fairly common in communities, relatively low levels of perchloroethylene can also be found in outdoors from "fugitive emissions" or leaks that are not controlled. Perchloroethylene can also be found in private and public drinking wells. Importantly, these air and water levels are substantially lower than federal standards; however, it is not known whether these low level exposures are dangerous to health.

The actual and potential dangers of perchloroethylene exposures have focused considerable attention on ways to reduce these risks. Risk reduction methods have followed two distinct but compatible strategies. The first strategy is to reduce perchloroethylene emissions from dry cleaners through improvements to equipment, maintenance, work procedures, and ventilation. While effective and important in the short run, this emission reduction strategy does not provide a permanent fix, as it still relies on the use of perchloroethylene, a known health threat. For this reason, the second strategy -- to phase in alternative, non-polluting cleaning methods -- makes an attractive permanent solution to the dry cleaning problem.

There are three commonly discussed alternatives to dry cleaning by perchloroethylene, including liquid carbon dioxide (CO2) (Hangers Cleaners), silicone-solvent based (GreenEarth Cleaning), and wet (or soap and water) cleaning methods. Although not completely characterized, each of these alternative methods would be a cleaner (pardon the pun) substitute for perchloroethylene. The CO2 and wet cleaning methods are thought to be the most environmentally and public health friendly. While the silicone-method is also thought to be environmentally friendly, there are mixed reports about its health risks.

An equally important question, though, is how they clean. Consumer Reports compared the cleaning ability of these methods with each other and with the traditional perchloroethylene method (http://www.consumerreports.org/cro/home-garden/cooking-cleaning/drycleaning-alternatives-203/index.htm). Their results showed that the CO2 cleaning method performed best, with silicone-solvent based cleaning a close second. The performances of both wet-cleaning and perchloroethylene cleaning were weak in comparison, especially for a lambswool jacket, which does not bode well for your cashmere sweaters.Despite the strong performance of the alternative methods, they are not available everywhere just now. Their use is currently limited by the costs of installing or switching to these methods, which are highest for the CO2 followed by the silicone-solvent based methods. These high costs are particularly burdensome for the typical small business dry cleaner. If you are lucky, however, you will have a conveniently located “green” cleaner near you. To check, the location of cleaners using the CO2 method, however, can be found at the Hangers Cleaners website (URL: www.hangersdrycleaners.com), while cleaners offering silicone-solvent cleaning are on the web site www.greenearthcleaning.com.

Musty Smells: Should I Buy The House?

Question:
I’m considering making an offer to buy a home but am hesitating because of concern about a strong musty odor in the basement. Should I be worried about this smell?

Response:
The strong smell is almost certainly generated by mold, which as it grows, can emit a mixture of gases that smells musty and earthy.

The strong musty smell suggests that there is a significant amount of mold in the basement of the home. Since mold requires moisture to grow, water must be entering the basement routinely – possibly through leaky windows, the foundation, or a leaking pipe. Chronic water problems can not only lead to mold but can also damage the home and lead to structural problems in the long run.

In addition to producing an unpleasant smell and signalling potential water problems, mold may be dangerous to your health. Some scientific studies, for example, have linked the mold-related smells to respiratory irritation. Of more serious concern, however, may be the mold spores themselves. Reports from the Institute of Medicine of the National Academies concluded that mold (and other factors related to damp indoor conditions) were related to asthma symptoms in people who have asthma and also to coughing, wheezing, and upper airway symptoms in people who are otherwise healthy.

If you love the house and would like to live there except for the musty basement, I suggest that you figure out why the basement is wet. Your real estate agent should be able to help you find a qualified mold professional to inspect the basement and identify where the mold is and how water is getting in the house. Based on their assessment, you could negotiate the cost of the assessment and of the solution with the seller. On the other hand, if you are only mildly interested in this property, you may want to pass on the house. Good luck!

Air Conditioners and Black Clouds

Question:
Our air-conditioner has begun emitting black, soot-like particles when we turn it on. We've tried cleaning the filter but it continues. Are these particles dangerous? Does this mean that we need a new air conditioner? Also, how do you know if an air-conditioner is leaking freon?

Response:
Window air conditioners contain rubber gaskets that can become brittle after many years of use. As a result, the rubber gaskets can eventually break apart into tiny pieces that can then be blown out of the air conditioner. If your air conditioner is more than several years old, the black dust is probably these little pieces of gasket that are blown from your air conditioner.

These gasket pieces are probably not dangerous. Since you can see the specks of the gasket, the gasket pieces are too big for you to breathe them into your lungs. It is possible that little gasket pieces can get into your body if they get blown on your food or if they get on your hands and you happen to eat them by mistake. But, this accidental ingestion of the gasket pieces are unlikely to be cause you any harm.

Although not hazardous to your health, it makes sense that you will want to either fix the problem or get a new air conditioner. Fixing the problem should be as simple as replacing the problem gasket or gaskets. You may be able to get a replacement gasket through your air conditioner manufacturer or at your local hardware store. Your air conditioning manufacturer may also have a technical support line that could tell you how to check for leaking freon. If you do have a freon leak, however, you might have very little or no freon in your air conditioner, especially if your air conditioner has been sitting around for a while. If so, your air conditioner will no longer blow cold air -- a pretty sure sign that something is wrong!

Why is my drinking water brown?

Question:
Recently, every time I turn on the tap, my water looks brown. What makes it brown and is it safe to drink?

Response:
Your drinking water may be brown because it has too much iron in it. Iron is a common, naturally occurring metal in soil, and as a result, is normally present in your drinking water. Under normal conditions, drinking water provides about 5% of the iron that you are supposed to drink or eat each day. You need iron to survive, as iron is an essential part of red blood cells and is used to trap oxygen and carry it from your lungs to other parts of your body.

Although not dangerous to drink, brown water is unappealing and annoying. Iron-containing water may have a funny, metallic taste and may stain white clothes, toilets, bathtubs, as well as other surfaces.

Iron can get into your water in several ways. It may get into your water when rust gets dislodged from water pipes. This can happen when pressure in the pipes changes, for example when water pipes are repaired or when water in the pipes is shut off and then turned back on again. If you get water from a well, it is also possible that more iron than normal entered your well water from the surrounding soil and dirt.

You can try an easy and quick fix to clear your water by running the cold water for about 20 minutes (probably from an outside faucet). If this doesn't fix the problem (and you get your water from a public system), you should call the town or city to ask whether the brown water is from the city's pipes. If it is from the city pipes, the city should send someone out to flush the brown water out from a nearby fire hydrant.

If these methods are unsuccessful, you will need to try other, more complicated treatment methods, such as aeration, filtration, chlorination, water softeners, and ozonation. The right treatment method for you will depend on several factors, including the exact form of iron in your water, the temperature, acidity (pH), and pressure of your water, and how much you are willing to pay and maintain your system. Since it is fairly complicated to figure all of this out, you should get the help of a certified water laboratory -- the names of which should be listed on your state environmental agency web sites. The testing laboratory will test your water for iron, temperature, pH, and hardness. Based on the answers, you will be able to choose between one or several treatment options.

You can double check the lab's answers by looking at how the iron in your water behaves. For example, if your water runs clear but turns brown after a few minutes, you have ferrous iron or rust in your water. In this case, you will have many treatment options, including probably the simplest option -- aeration and filtration (if your water fits within a certain temperature range) -- and the most expensive option, ozonation.

On the other hand, if your water is rust colored as soon as you pour it, it contains either ferric iron or organic iron. It is ferric iron if brown particles start to settle on the bottom of your glass. In this case, treatment options will be more straight-forward, including only filtration-based methods. If your glass remains particle free after several minutes, your water contains organic iron; this generally only occurs if your water comes from a well. Treatment options include water softeners, filtration, and ozonation.

For more detailed options on treatment methods, you should check out this document http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/he394.html. I think that it is pretty good.

Removing Pet Dander and Hair

Question:
Your blog is interesting; very clear and easy to understand. Do you have any advice on reducing pet hair and dander (in addition to vacuuming) in a home where people suffer from allergies?

Response:
Pets allergies can be a significant problem not only for people living with the pets but also for their visitors. Short of finding your pet another home, pet allergies can be best reduced by removing exposures to pet dander, loose skin flakes, hair, urine, and saliva --the main causes of pet allergies. This basically means that you have to get rid of all pet produced allergens (or allergy-causing pet products) -- a difficult and if not impossible task, especially for cats, which have particularly "sticky" dander.

The reason that it is so difficult to get rid of all pet allergens is that pets produce these allergens constantly and that once produced, these allergens (especially from cats) can be carried everywhere. As a result, your house can only be kept clean of pet allergens if you clean your home constantly. The best and most feasible way for you to do so will be to install a whole house air cleaner or several portable air cleaners (see my earlier posts for information on air cleaners). In addition, you will need to clean your furniture and surfaces (especially cloth surfaces) using a vacuum cleaner with HEPA bags. As I discussed in my earlier post on home renovation and dust, HEPA bags in your vacuum cleaner will make sure that any dust picked up by your vacuum cleaner stays in your vacuum cleaner.

These cleaning methods should be accompanied by other ways to minimize your exposures to pet allergens, including frequent hand washing (especially after touching your pets), keeping your pets off the furniture, installing blinds instead of curtains, and keeping your pets outside as much as possible. Also, you should keep pets outside of rooms in which you or the allergic person spends a lot of time, such as bedrooms. You should keep in mind, however, that pet allergens will still get inside these rooms (especially if you have cats), as the pet allergens will be brought into the rooms through your clothes, shoes, bags, and other items that travel room to room. I know that many of these potential solutions are challenging and at least in my house seemingly impossible. But, following these suggestions as much as you can should help to minimize pet allergies.

Living near construction: Should I be worried?

Question:
A large apartment complex is going to be built in my neighborhood, starting next month and lasting through the year. There is already a lot more congestion and many more construction vehicles near my house. Will this construction activity be dangerous to my health? What can I do to minimize the impact of this construction?

Response:
As you are already witnessing, construction has many impacts on surrounding neighborhoods. Construction tends to be loud, dusty, and bothersome. If the construction includes demolition, some of the generated dust may contain pollutants, such as asbestos or metals, that are potentially harmful. Also, construction is likely to increase congestion in your neighborhood -- both from usual and rerouted traffic and from construction vehicles. This increased congestion generally means more pollution for your neighborhood.

Since scientific studies have shown that construction dust and traffic pollution (in particular from trucks and other diesel-powered vehicles) have negative impacts on health, I think that it would be wise to reduce your exposure to construction-related pollution. This is especially true if you or anyone in your household are old (say over 65) or very young, are in poor health, have an existing heart condition, are diabetic, or are asthmatic.

There are some very easy and inexpensive ways to reduce your construction-related exposures. As a first step, you should keep your home's windows and doors closed and avoid being outside, especially when construction is occurring. If your home is right next to the construction site, these simple steps will be particularly important and can be accompanied by other measures, such as placing any room air conditioners as far away from the construction as possible, since air conditioners can draw air from the construction directly into your home. You could also improve seals around your windows and doors and/or get an air cleaner.

Also, you may want to check with local citizen groups that work with (or sometimes against) developers to minimize health risks for surrounding neighborhoods. I have often advised local citizen groups to understand the impacts of construction or development in a neighborhood and have found them to be effective and well informed advocates for their neighborhood. At their best, citizen groups work with developers to make sure that in the end, the construction will result in an improved neighborhood with more green space, bike paths, and common areas. You could check with the citizen groups about these plans and to make sure that the construction site is following exposure reduction measures required by local and state governments. In Massachusetts and other states, for example, trucks are not allowed to idle for more than 5 or 10 minutes and can only load and unload in pre-assigned areas -- both measures designed to minimize construction impacts on the surrounding neighborhood.

Radon testing: What do the results mean?

Question:
I am selling my house and in this process, my house was tested for radon using a mail-in kit. The buyers got the radon results back and they show that my house is just below the EPA recommended limit. The buyers want me to install equipment to reduce radon in my home. I don't think that this is is necessary, because my radon levels were just below the limit. If radon levels are below the EPA limit, doesn't that mean that my radon levels are fine?

Response:
Radon is a naturally occurring gas that has been shown in research studies to cause lung cancer. People are exposed to radon primarily in their homes, as that is where people spend the majority of their time and that is where radon levels (in every day life) tend to be highest.

EPA recommends that people take steps to reduce radon levels in their home when levels are at or above 4 pCi/L. Since exposures to radon at even lower levels carry some risk of lung cancer, EPA recommends that people think about lowering their home's radon levels to even lower levels, or to 2 pCi/L. Lowering radon levels will be particularly important for areas where people spend time.

To know how your home fits within the EPA guidelines, you need to know the average radon levels in your home over a long time period, as EPA developed these guidelines based on life time exposures to radon. Since your radon levels were measured using a mail-in kit, my guess is that your radon test was performed over a couple of days. Your test results near the 4 pCi/L action level indicate that it is possible for your home to have long-term average radon levels that need remediation (or lowering).

Since your test results were just under the action level, however, it is not clear that you need to remediate. Radon levels vary over time -- for example higher indoor radon levels are generally found in winter. As a result, it is possible that long-term radon concentrations are lower than measured. To check, you can retest your home for radon, making sure to place the radon kit in the same place as before (usually the basement or first floor is recommended). You could estimate the long-term average radon level as the average of the two test results. It's far from perfect, but retesting will give you more information to decide what to do. If the second test result is much greater than the 4 pCi/L action level, for example, I would assume my radon levels were too high. If the retesting results were much lower, then I would assume that my radon levels were within the recommended levels. If the test results are again close to 4 pCi/L, then the decision is harder.

Alternatively or in addition, you could just propose a radon mitigation or reduction solution that you have installed or provide funds to cover the costs for installation. This might be the easiest and quickest way to reach a suitable resolution with the prospective buyers of your home. Some radon reduction fixes are relatively easy and inexpensive to do, while others are more labor-intensive and costly. EPA estimates that radon remediation ranges between $800-$2500.

EPA has a good website about radon for home buyers and seller (http://www.epa.gov/radon/realestate.html). This site contains pretty user-friendly information about radon, its health risks, measurement, and remedies. On this website, EPA mentions their video "Breathing Easy: What Home Buyers and Sellers Should Know About Radon", which you may find helpful. To get a free copy of this video, you can call 1-800-438-4318 and ask for video number EPA 402-V-02-003.

Diesel exhaust and heart disease

Question:
I am a retired fireman who has developed heart problems. In the fire station, there were a lot of diesel fumes. Are these diesel fumes responsible for my heart problems? Could they have affected my health?

Response:
Diesel exhaust exposures have been linked to heart (and lung) problems in many research studies. These studies show fairly consistently that higher levels of diesel pollution in the outdoor air is related to higher number of deaths, hospital admissions, heart attacks, and other bad health outcomes. Since these studies base their results on populations (and not individuals), their results say that on average an increase in bad health outcomes may occur for the group that they studied, often a group of people living in a particular city or a group of elderly people.

What this means for you is not that clear. Even though these studies show that inhaling diesel fumes is bad, they don't necessarily say anything about whether diesel fumes in your firehouse are responsible for your specific heart problems. You (with some help and guidance) could estimate your risk of heart problems from diesel exposures in the fire house, given your family, diet, exercise, smoking and work history; scientists and consultants do this all the time. However, to do so properly, you would need to make many assumptions and factor in your exposures from fighting fires, when you probably inhaled soot and other pollutants that can also damage the heart. Without doing the calculations, I would guess that breathing diesel exhaust in the fire house does create additional risks of heart problems for you, but these risks are likely to be small, especially relative to those from fighting fires.

For more related information and more detailed explanations, I liked the following links: http://www.healthfinder.gov/news/newsstory.asp?docID=532393 (news article that talks about heart attacks and firefighters);
www.arb.ca.gov/research/health/fs/PM-03fs.pdf (a review that talks generally about the impacts of air pollution in California)
http://erj.ersjournals.com/cgi/content/abstract/17/4/733 (a scientific review article about the health impacts of breathing in diesel exhaust)

Portable vs. In-Duct Air Cleaners

Question:
What is the difference between a portable air cleaner and an air cleaner added into my central heating and cooling system? I can’t tell whether central or portable air cleaning systems are better.

Response:
Portable air cleaners are small appliances that typically are placed on the floor of a room in your home and plugged into an electrical outlet. They are designed to clean one room in your home. A whole house or in-duct air cleaner is added to your central air handling system and is installed by an HVAC contractor. Whole house air cleaners clean air inside rooms that are served by the central air handling system.

To use a whole house air cleaner, you will need to have a central forced air handling system. If you do have such a system and you want to clean the air in your whole house, an in-duct air cleaner will likely do a better job than portable air cleaners. This is because the in-duct air cleaners tend to have a much higher Clean Air Delivery Rate or CADR, which tells you how much air the device can clean. For best performance, the CADR should be approximately equal to the square footage of the indoor space that you want to clean. [For more info, see my earlier entry about portable air cleaners.] Also, whatever air cleaner you choose should be labeled as at least 98.98% efficient or HEPA, which means the device performs as a high efficiency particulate air cleaner. A HEPA-grade whole house air cleaner will typically have CADR ratings of about 1200, while the CADR for portable air cleaners is much smaller -- about 250. Theoretically, five portable air cleaners would provide the same performance as one in-duct air cleaner (250 times 5 equals 1250). However, testing has shown that this is not true. In fact, five portable air cleaners together have a CADR of only about 600, since portable air cleaners are not as effective at cleaning air outside their immediate vicinity.

For more detailed information about whole house and portable air cleaners, you may want to check out a report of a study funded by the air cleaner manufacturer TRANE, which compared the performance of several air cleaners, including their own in-duct air cleaning system. Since I know the person who led the study very well (and since I advised in the design of the study), I believe that the data and results are fairly and accurately reported, even though I am usually suspect of studies funded by a group that has something to gain by the results. This report can be found on the internet at www.trane.com/Residential/Downloads/EHE_study.pdf.