Friday, January 26, 2007

Musty Smells: Should I Buy The House?

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?

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!

Wednesday, January 24, 2007

Air Conditioners and Black Clouds

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?

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!

Friday, January 19, 2007

Why is my drinking water brown?

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

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 I think that it is pretty good.

Thursday, January 11, 2007

Removing Pet Dander and Hair

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?

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.

Wednesday, January 10, 2007

Living near construction: Should I be worried?

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?

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.

Monday, January 8, 2007

Radon testing: What do the results mean?

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?

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 ( 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.

Thursday, January 4, 2007

Diesel exhaust and heart disease

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?

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: (news article that talks about heart attacks and firefighters); (a review that talks generally about the impacts of air pollution in California) (a scientific review article about the health impacts of breathing in diesel exhaust)

Tuesday, January 2, 2007

Portable vs. In-Duct Air Cleaners

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.

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