Many of the recommendations that I and other indoor air quality professionals make can be very expensive – like installing hardwood or tile floors, or replacing a hot-air heating systems with baseboard or radiator heat. But there are a number of things you can do that won’t cost a fortune and that can help keep the air in your home clean and allergen and irritant free. Below are 15 examples.

1. Remove your shoes when entering the house, and ask that other family members and guests do the same. This will help keep soil out – and some of that soil can even contain lead dust, if you and neighbors live in homes more than 30 years old and that have been scraped and painted.
2. If you have plants indoors, put a waterproof dish under each pot. If the room is carpeted, be careful not to spill water on the carpet, because this may lead to mold growth.
3. Not to be indelicate, but remember to close the toilet before flushing to minimize bioaerosol (airborne particles that come from living things, such as bacteria and even the H1N1 virus).
4. Don’t burn jar candles, which can produce a lot of soot. Soot particles are unhealthy to breathe in and of themselves; in addition, they can act as surrogate (substitute) allergens if they’ve been in contact with mold or pet dander, and then become re-aerosolized.
5. Use a vacuum with a HEPA (high efficiency particulate arrestance) filter, because conventional vacuums spew out allergens and irritants in their exhaust. If you hire cleaning help, be sure they use your vacuum, and not their own. If you have a central vacuum system, be sure the system exhausts to the exterior and not into your garage or basement.
6. Avoid using laundry detergent that contains enzymes, because these chemicals can exacerbate asthma symptoms.
7. To help control mold growth, dehumidify your basement in the humid season. Keep the relative humidity at or under 50%. And if you have a finished basement, keep it consistently warm (thermostat set at a minimum of 60ºF), whether you are using the space or not.
8. Only use a dehumidifier that condenses water and not one that only exhausts air. Don’t run the dehumidifier in the winter.
9. If you have a garage that is attached in any way to your house, don’t leave the car running in the garage, or combustion products can flow up into habitable spaces.
10. Be sure you have an exhaust fan over your stove, and that the fan vents to the exterior. This will help reduce moisture, cooking odors and combustion products in the house.
11. After showering, leave the bathroom door open, and operate a table or tower oscillating fan in the room (plugged into a GFI outlet, please) for an hour, to speed drying of surfaces and help prevent mildew growth.
12. Dogs and cats are living dust mops. If you have a dog or cat, don’t let the pet sleep in the bedroom of someone with allergies or asthma – like your son or daughter – and keep your pet out of the basement if it smells musty.
13. If anyone in your family is allergic to dust mites, be sure every mattress, box spring and bed pillow in the house has a dust-mite cover. Use the covers with polyurethane liners. You can save money by buying the all-plastic encasings for the box springs and mattresses; just put an extra-thick, cotton mattress pad on top, so the sleeper won’t feel the plastic. Never take a dust-mite cover off a mattress unless the mattress was new to begin with, because then dust-mite allergens will escape into the room.
14. If you have baseboard or radiator heat, vacuum the baseboard convectors or the surfaces of the radiators before the heat turns on each year, to get rid of irritating, allergenic dust. Use a 36-inch vacuum crevice tool (Google 36 inch vacuum crevice tool) to get to hard-to-reach places.
15. Clean your portable air conditioner before you use it for the first time every year, and add filter material (at least MERV 7) to the intake grill, to help keep the cooling coil clean. If you have central air conditioning and/or hot air heat, use a MERV-8 pleated media filter in the air handler. Be sure the filter holder is air tight (you can cover it with duct tape if it’s open), and change the filter as frequently as is needed.

If your son or daughter has allergies or asthma, there may be conditions inside the school building that could cause your child to experience health symptoms. What are some of these conditions, and what you can you as a parent do about it?

Carpeting. Many modern school buildings have wall-to-wall carpeting, which is often cleaned in the summer, when weather is most humid. If the carpeting remained damp for more than 48 hours, it may well contain mold growth, subsisting on captured dust. If your child’s classroom smells musty, the carpet may be the culprit. Ask the school to have the carpet dust tested for mold (or contact DACI lab at Johns Hopkins University and find out how to take a sample yourself).

If mold has grown in a carpet, the contamination cannot be removed completely by traditional steam cleaning. Treatment with steam vapor may help, but in the end, the carpet may have to be replaced. Meanwhile, the carpet can be covered with an adhesive-backed plastic like Pro-Tect.

Pets. Sometimes a teacher will have a pet rabbit or some other animal in the classroom, or even a fish tank. If your child is allergic to the animal, ask that the pet be moved to another room. And believe it or not, fish tank covers can be home to dust mites, thriving on the protein in the fish flakes spilled on the rim or stuck to the cover, and basking in all that warmth and moisture. Then mite allergens can become aerosolized when the cover is opened. If your child is allergic to dust mites, ask the teacher to keep the rim and cover of the tank clean.

Books. Times are lean, so I don’t blame teachers who collect children’s books at yard and library sales. Such books, however, can be covered with mold growth, especially if they’ve been stored below-grade (below ground level). If any books in the classroom smell musty or have visible mold spots (particularly on the spines), ask that they be removed from the room.

The front door. Children should not enter a school building directly onto permanently installed carpeting, because then moisture from their shoes can fuel mold growth. Ask the school to put a replaceable mat on top of the carpet in front of entrance and exit doors.

Below-grade spaces: Many modern school buildings have classrooms, the library, or even the gym partially or fully below-grade. If not adequately dehumidified in summer, such spaces often become contaminated with mold. Ask your child to try to keep track of any symptoms he or she experiences. If the symptoms worsen in below-grade spaces, your child may have to be excused from gym or library time until the spaces are cleaned.

Resources:

· The EPA’s “Tools for Schools” offers an overall indoor air quality plan for schools (800-438-4318; www.epa.gov/iaq).
· Check the EPA site for “Mold Remediation in Schools and Commercial Buildings (www.epa.gov/mold/mold_remediation.html).

Your child spends a lot of time in the school building. Don’t be complacent if you think there are conditions there that are threatening your child’s health.

Of all the environmental hazards in houses, lead paint is potentially one of the most serious, because it can and does have the largest number of victims. Lead-poisoned children number in the tens of thousands and suffer from reduced learning skills, behavioral and nervous system disorders, and in the worse cases of poisoning, mental retardation. Lead can also affect unborn children.

Up until 1978, nearly all exterior paints and most interior wood trim paint contained lead pigment. In the Boston area where I live, 80% of the homes contain lead paint, because much of the building stock in the city is older. If you live in an older home, contact your local health department to see what you must do about lead paint.

Below are some things to keep in mind to help protect yourself and your children from lead exposure.

1. Be careful when you renovate. One husband and wife wanted to sell their home, and their real estate agent suggested they repaint the interior to freshen up the property. They had two young children and not a lot of money, so they decided to do the work themselves. They diligently sanded and scraped wall and wood surfaces to prepare them for a new coat of paint – all while living in the house. They accepted an offer, and the prospective buyers hired a lead inspector. The inspector drew everyone aside during his site visit and said that the house contained the highest levels of lead dust he’d ever seen. Even the infant’s crib and teddy bear were contaminated. He suggested that the family evacuate the home immediately.

2. If you live in an older home, and have a sandbox outside your house, or a dirt pile for your children to play in, buy new sand or dirt– don’t use dirt from your yard. Don’t grow fruits and vegetables in the soil around your house until you have that soil tested. Make people take off their shoes when they come into your home. The soil around older homes can contain high concentrations of lead compounds – perhaps because the siding contains lead paint that was scraped before surfaces were repainted. Some people also think that lead compounds in our environment came from gasoline, before the additive tetraethyl lead was banned from fuel. When this chemical was in fuel, lead ended up in the exhaust of cars and trucks, and entered the air at a rate of about the weight of a penny for every 5 miles traveled. These microscopic lead particles found their way into the soil around houses after being washed out of the air and off of roofs.

3. If you are thinking of moving into an older home, hire a professional to do a lead inspection. Don’t forget to have carpeting tested, because it may contain soil and dust that people carried into the house on their shoes and that contains lead dust. If the property has already been de-leaded, ask to see the final lead inspection report.

Lead paint chips are not sweet and children rarely eat them. Invisible lead dust is a more worrisome culprit.

(c) Jeffrey May

Soot particles are small enough to be breathed deeply into the lung and even pass directly through capillary walls into the blood stream. The particles may contain carcinogens – such as benzo[a]pyrene – and can also act as “surrogate allergens.” The medical community recognizes that the cornstarch powder in latex gloves (used to keep the rubber from sticking to itself) can acquire latex allergens. When the powdery granules become airborne and are inhaled by someone who has latex allergy, that person can experience an allergic reaction – sometimes severe. Similarly, the microscopic particles of soot that settle on surfaces that contain mold or pet dander can become contaminated with allergenic substances. The particles can then become airborne again and be inhaled when surfaces are cleaned or otherwise disturbed in some way.

Now I have to talk a little bit about chemistry (ugh, groan, I hear you say….but chemistry is one of my favorite subjects!). Complete combustion inside a gas furnace or boiler results in the formation of carbon dioxide (CO2) and water (H2O) vapor. In other words, one atom of carbon (C) from methane (CH4) combines with two atoms of oxygen (O) from the air to produce CO2 (one carbon atom, two oxygen atoms). Four hydrogen atoms combine with two oxygen atoms to form two water molecules (H2O). If the combustion is incomplete, however, some of the carbon combines with only one atom of oxygen, resulting in carbon monoxide, or CO (one carbon atom, one oxygen atom). When there isn’t enough oxygen, combustion is incomplete. Then some carbon atoms combine with oxygen to create carbon monoxide, other carbon atoms combine with oxygen to create carbon dioxide, and still other carbon atoms do not combine with any oxygen but rather they combine with each other to produce soot (“C”).

What creates soot in our indoor environments?

A gas furnace or boiler that is not firing properly or that does not have sufficient make-up air can produce soot. And even though the furnace or boiler may be located in the basement, if the combustion products are getting into the basement air, airflows carry the soot up into habitable rooms above.

Gas fireplaces can produce soot. When soot particles are heated in a flame, the particles become incandescent (glow) and give off a yellow light. The gas in gas fireplaces is not premixed with enough air, so the flames are yellow due to inadequate oxygen (otherwise they’d be blue, like the flames coming from a gas cooking stove – not exactly what people expect to see in a fireplace!). If there is inadequate draft for a gas fireplace that is producing soot, the particles can leak into the house and stain the walls and ceilings black.

People love jar candles, because of their pleasant scents and yellow, flickering flames; but jar candles also produce a lot of soot, even if burned for only a few hours. As the air moves in and out of the jar, it disturbs the flame structure and causes incomplete combustion. If you burn jar candles, look at the jar rim. Is it black with soot? Imagine the soot that candle released into the air that you and those you love then inhale.

Soot staining in older homes can be fairly uniform, sometimes visible only when pictures are removed, revealing whiter surfaces beneath where soot has not deposited – though in some Victorians, the soot pattern mimics the horizontal “stripes” of underlying plaster/lath, darkest at the plaster “keys.” In newer, better-insulated homes, soot stains on exterior walls and on ceilings near exterior walls look like vertical stripes on studs, with darker black dots at the nail heads. Wherever air moves more turbulently due to temperature differentials, the air will impact surfaces that much more frequently and deposit the soot particles it carries in its flows. (Dark spots develop in bathrooms above vanity fixtures for the same reason: increased deposition rate due to hot air rising above the bulbs.)

I know of one homeowner whose insurance company spent $5,000 to have all the rooms in his house repainted. The man continued to burn jar candles, however, and had to repaint the house all over again. So protect the value of your property by choosing tapered candles over jar candles (just don’t burn the candles near a window or door, where airflows may disturb the flame). Better yet, choose the battery-operated, fake candles that look like the real thing.

Of course, money is important, especially in these lean times. But your health and the health of those you love – including your children – are paramount. So stop burning jar candles. If you don’t burn candles and you still see soot stains on your walls or ceilings, have a professional evaluate your furnace or boiler and undertake necessary maintenance or repairs.

Your family is growing in size and you have to find a roomier home. You may feel lucky if the person moving out is leaving behind a refrigerator or some stylish carpeting, but beware. Many things left behind in a house should be cleaned or removed prior to occupancy, especially if you or someone else in your family, particularly a child, has allergies, asthma or other environmental sensitivities.

1. The Refrigerator. There is often allergenic dust on the sides and back of the appliance, as well as dust trapped in the coils and insulation. These surfaces can be HEPA vacuumed with a 36-inch crevice tool (found on-line; Google “36-inch crevice tool” AND “vacuum”). A drip tray, if present, can be contaminated with mold, bacteria and yeast. When the refrigerator compressor turns on, by-products of this growth can become airborne and be inhaled. The tray should be removed and cleaned. A few tablespoons of salt in a clean plastic (not metal) drip tray can help deter such microbial growth. (In newer refrigerators, the drip tray is on top of the compressor and only accessible for cleaning from the rear after removal of an access panel; salt shouldn’t be used here.)

2. The Washer and Dryer. Biodegradable lint can pile up in back of a dryer, and if the washer has ever leaked, there can be mold growth on the floor or the lower few inches of wall behind the appliance. The washer/dryer should be moved and the area thoroughly cleaned. The dryer hose should be checked to be sure that it’s not kinked or squashed, and that it vents to the exterior. For confined spaces, I recommend a solid metal, periscope-style dryer duct rather than a hose that is likely to be crushed. Never use flexible plastic hose.

3. Built-Ins in Unfinished Basements. Below-grade spaces are prone to mildew growth, so work benches, pegboards to hold tools, and built-in wooden shelves and seats are often covered with mold, and should be removed or cleaned and painted to adhere moldy dust.

4. Carpeting and Built-Ins in Finished Basements. I would say that more than half of the finished basements I investigate end up in a dumpster because they haven’t been consistently dehumidified in spring/summer/early fall or heated in the colder months. Relative humidity has thus been elevated and mildew has sprouted, usually invisibly, on the lower few feet of walls and built-in bars, on the bottoms of shelves, and in carpet dust. (Hold a bright flashlight parallel to smooth, finished vertical surfaces to see the spots of probable mold colonies at the lower foot or two, as well as higher up on outside corners.) A moldy carpet should be removed under containment, and replaced with vinyl or ceramic tile flooring. Any built-ins should also be removed or cleaned and painted to adhere residual dust. The lower few feet of pressed-board or painted walls can be cleaned with a bleach/water solution or a household cleaner suited for the purpose. Unfinished wood should be lightly sprayed with paint or an appropriate sealant, to adhere residual dust. If off-gassing is an issue, use an Elmer’s glue and water solution (one part glue to one to two parts water). Painted surfaces can be repainted.

5. Carpeting in Other Spaces. People often replace wall-to-wall carpeting in rooms but leave the carpeting on stairs and in hallways, yet it is these areas that often receive the most foot traffic and where the carpeting is sometimes most severely contaminated with allergens from pets, dust mites, and even mold growing on captured dust.

6. Window Treatments. Some window shades off-gas a vinyl smell that can be irritating to those who are sensitive to chemicals (like fragrances). Such blinds should be removed from the house, along with the Seller’s other possessions. Sometimes curtains contain mold growth on surfaces that are near the cool floor or that have rested up against a cool window or slider. Curtains and drapes can also be full of allergens from pets and dust mites. Such curtains should be cleaned if possible or replaced.

7. Furniture. Perhaps the family moving out of the home is downsizing and thus is interested in selling you some furniture. If that includes a bed or two, replace each mattress and box spring, and clean the frame of all dust. If any of the furniture pieces are antiques, they may have been stored in a damp basement or garage at some point and can contain a nearly invisible fuzzy film of mildew growth on solid surfaces, especially the bottoms and backs; there may also be mold growth in cushioning or on upholstery. If you want to accept such hand-me-downs, buy new mattresses, reupholster pieces, and clean solid surfaces. Inheriting someone else’s dust mites and other allergens and irritants shouldn’t be part of the deal.

©2009 Jeffrey C. May

If you have a child with allergies or asthma, you probably work hard to keep your home and the air inside your home as clean as possible. But there are some things you might do or buy that can actually introduce rather than solve indoor air quality (IAQ) problems.

Let’s start with a hot-air heating and/or central air conditioning system – often a source of many allergens and irritants in a home.

1. Electronic filters are efficient in theory but lose their filtering capacity quite quickly as they get dusty. Since people rarely clean such filters frequently enough (monthly), these expensive filters (often costing upwards to $1,000 each) end up being pretty next to useless – kind of like using gold jewelry as a paperweight.

2. Washable electrostatic filters are also expensive ($100 or more) and also are rarely cleaned often enough or thoroughly enough, so in my opinion these filters are a waste of money.

3. A turbulent flow precipitator consists of several media filters stacked in a holder. Air passes over rather than through the filters. Supposedly, multiple passes of air over the pleats cause the air to rotate, and dust to deposit on the filter surfaces. In reality, despite being passed over the filters a number of times, many airborne particles get past the filter array and still enter the mechanical system, where in the presence of moisture, they can become nutrients for mold growth.

4. Ultra-violet (UV) lights are either supposed to disinfect the air or keep the system free of microbial growth (yeast, mold, bacteria). Germicidal UV has been used successfully for decades to disinfect air, but the homeowner versions do little to disinfect the air stream and cannot sufficiently clean interior surfaces in an already soiled air conveyance system. (A pivotal Canadian study concluded that UV irradiation would improve the health of millions of allergy sufferers. The study’s methodology, however, was flawed and thus the conclusion invalid.)

The best way to keep a hot air and/or central air conditioning system clean is to have the best filtration possible: a disposable pleated media filter with a MERV rating of at least 8 (MERV stands for minimum efficiency reporting value). Families with allergies or asthma should use a MERV 11 filter, like the Aprilaire, though the duct system will have to be altered to accommodate the deeper filter. Whether rated MERV 8 or MERV 11, the filter should be in an airtight filter holder, to prevent air from by-passing the filter and entering the system unfiltered; a one-inch media filter should be changed at least twice a year, depending on the manufacturer’s recommendations. (A one-inch media filter with a MERV-8 rating must be changed more often than a two-, four- or five-inch MERV-8 filter, because the static pressure builds up faster in a thinner filter, reducing the airflow.)

What else do people acquire in an effort to keep the air in their homes clean?

1. Air-to-air heat exchangers, also called energy recovery ventilation (ERV) or heat recovery ventilation (HRV), are devices that exhaust stale house air and introduce fresh outdoor air into the building. There are a few problems with these units, however. First, most lack a pre-filter to prevent the buildup of outdoor pollen, mold, plant materials, and insects inside the unit. Second, the built-in filtration within the unit itself is usually inadequate, so dust builds up on the heat exchanger. Whether in winter or summer, hotter air meets colder air within the heat exchanger, and condensation may occur. In fact, many such units that I’ve seen lack any accommodations for drainage, even when the exhausted air comes from bathrooms or the kitchen – adding even more moisture to the device. The presence of dust and moisture lead to mold growth, so it’s no surprise that almost every single HRV I’ve opened was full of mold growth. Then spores or other mold allergens are circulated in the air stream. If you have an air-to-air heat exchanger in your home, make sure you clean the interior (including the “core”) on a regular basis, and replace or clean the filter at least four times a year. If possible, eliminate the two internal filters and use in-line, external media filters at least two inches deep with at least a MERV 8 rating. If you are only thinking about installing an air-to-air heat exchanger and aren’t the type of person to take care of regular maintenance tasks, please think again and open a window now and then instead.

2. To finish off my rant, I have to complain about ionizing air purifiers. People like them because they make the air smell “clean” – like outdoor air. That fresh outdoor smell is caused by ozone – an irritating gas that is one of the major components in smog. If you want to use an air purifier, use one with a pleated media filter or a HEPA filter, and be sure it doesn’t have the air discharge at the base, which can disturb and make airborne more irritants and allergens than the machine can remove. But remember that IAQ problems aren’t born in the air itself. Air, like water, is a fluid, and like water, it carries gases and particles in its flows. So if you think that the air in your home is causing you or someone you love to cough, sneeze or wheeze, find and eradicate the sources of the airborne irritants and allergens, rather than try to “clean” the air. No air purifier can ever cleanse the air sufficiently, as long as sources of IAQ problems remain in a space.

Your family is growing, and you need more room.

The real estate market is slow, though, so instead of buying a larger home, you may be considering finishing your basement to gain a playroom, office or exercise room.

Maybe that’s your New Year’s Resolution, and you plan to hit Home Depot for your supplies and get started on the project.

Let me issue you a warning. Most of the finished basements I’ve seen end up – or should have ended up – in a dumpster, because finished, partially or fully below-grade (below ground level) spaces can easily become contaminated with mold growth. Then children playing on moldy carpets, or parents exercising in the basement can disturb and breathe in huge concentrations of mold spores – an unhealthy situation.

Mold can grow within twenty-four to forty-eight hours wherever food sources (such as skin scales and insect body parts in dust, and cellulose in drywall, cardboard and paper) and moisture are present. It’s impossible to live in a dust-free environment, but you can work to control moisture, which will help prevent mold growth.

Many basements experience water intrusion during heavy rains, because the ground is sloped toward the house, the gutters and downspouts are clogged with debris, or the downspouts empty water next to the foundation. Inside sources of basement water can include a leaking hot-water tank and water pipes, as well as an overflowing washing machine.

Even a seemingly dry basement is vulnerable to mold, because many indoor molds, including some species of the highly friable and allergenic Aspergillus mold, can grow when the relative humidity is in excess of 75%. As air cools, its relative humidity rises. The temperature of the earth around a foundation is approximately 55°F (colder in winter), so a below-grade space is naturally cool and thus the air has a higher relative humidity. Dust captured in basement carpeting, as well as dust on basement furniture surfaces facing the cool floor, gets moldy. Mold can grow on the lower few feet of walls or even on acoustical ceiling tiles, if the relative humidity is high enough.

As an indoor air quality professional and the parent of two children with asthma, I’d like to offer you some advice about finished basements:

1. Rather than finish your basement, finish your attic, or buy a futon couch for your guest room. Then the room can serve as a bedroom when needed and a playroom at other times.

2. If you remain committed to finishing your basement, build finished walls about two feet away from the foundation, to leave a space you can access to watch for pest activity or water intrusion. If building codes allow, insulate the foundation walls with two-inch solid sheet foam insulation, rather than put fiberglass between the studs of the finished walls. Leave the top inch of the foundation wall exposed, however, so you can keep an eye out for termite activity. Never install exposed fiberglass in a basement; cover it with Tyvek, stapled to the joists. (If your basement has exposed fiberglass and you haven’t controlled basement relative humidity with dehumidification, I encourage you to have the insulation professionally removed under containment, and the ceiling framing HEPA vacuumed and lightly paint-sealed – especially if you’ve had mice in the basement.) If you decide to install an Owens-Corning basement system, seal the exposed fiberglass insulation at the back with an adhesive plastic that will stick permanently (try Pro-tect, available in many building supply stores; www.pro-tect.com). Avoid wall-to-wall carpeting below grade. Put ceramic tile on the concrete, or lay two-inch solid sheet-foam insulation down on the concrete, then plywood, and then vinyl flooring.

3. If you already have a finished basement, and anyone in your family suffers from allergies or asthma, have the space professionally evaluated for mold, especially if any part of the basement smells musty.

4. To prevent mold growth, finished below-grade spaces must be consistently dehumidified in the humid season. Keep windows to the exterior as well as the basement door closed while dehumidifying, and doors to basement closets and rooms open. Be sure to use a dehumidifier with sufficient capacity for the space (see www.therma-stor.com). Attach any dehumidifier to a condensate pump that discharges into a sink, a sump or to the exterior. Then if the dehumidifier has a bucket, you won’t have to empty the bucket all the time to prevent the dehumidifier from shutting off because the bucket is full. Measure the relative humidity (RH) with a hygrometer, available in many hardware and building supply stores. Therma-stor also offers a Humidity Alert, which records the relative humidity (RH) and sounds an alarm if the RH exceeds the set point. Increase dehumidification if the RH exceeds 50%. Consistent air conditioning can be used to replace dehumidification, but always measure the RH.

5. To control the RH in cool weather, consistently heat all finished basement spaces – with the thermostat set at a minimum of 60°F – whether you are using the basement or not.

Avoiding mold growth in a finished basement can be expensive, but in the interests of health, it’s worth the cost. And the money you spend will still be less than buying a new house.

The ragweed season is over, and the air outside feels clean and crisp. Thanksgiving, Christmas and Hanukkah are approaching.

It’s an exciting and busy time of year, but also one in which parents with children who have asthma or allergies have to be careful not to introduce irritants and allergens, along with their holiday traditions, into their homes.

(Photo: (c) Jeffrey May 2008: The jar rim is black, but most of the soot from this candle went into the air.)

Below are some tips to help you keep the air in your home contaminant-free during the holidays.

1. Cooking. You may be cooking more now than at any other time of year. Smoke can be irritating to breathe, especially for those who already struggle with respiratory health symptoms. In addition, carbon monoxide from poorly adjusted gas burners can cause headaches (a yellow flame on a burner is a sign of carbon-monoxide emission). When you cook, use the stove-exhaust fan, which in the best of all possible worlds should be vented to the exterior.

2. Candles. Jar candles can be soothing, but they also produce a lot of soot, which causes costly cosmetic damage by staining walls and ceilings. Soot particles are also small enough to remain suspended permanently in air and to be breathed deeply into the lung. And if the particles happen to impact potentially allergenic substances like mold or pet dander, they can act as surrogate allergens. So avoid burning jar candles. Tapered candles are okay, as long as they are not placed in drafty areas, because a flickering flame also produces soot.

3. Fragrances. Some people find fragrances irritating to breathe, so don’t use anything that emits a smell associated with the holidays, including pine-scented candles and plug-ins.

4. The Fireplace. A wood fireplace or stove is cozy during the holiday season. Wood, however, can be contaminated with fungi, so store your firewood outside, covered and up off the ground. Promptly vacuum up any bark or wood bits that fall on the floor when you carry the wood inside. If you have a gas fireplace that vents to the interior rather than exterior, don’t use it too often, and have a carbon monoxide detector nearby.

5. Greens. Christmas trees and decorative boughs can get moldy. If anyone in your family is sensitized to mold, consider having an artificial tree and boughs instead.

6. Stored Decorations. Many families use the same holiday decorations year after year, and store them in a basement, attic or garage. Unfortunately, these areas accumulate allergenic dust. When you first take your decorations out for the holidays, clean the boxes they are stored in thoroughly with a suitable household- cleaning product before bringing them into the living room. If the decorations are not stored in boxes, clean them individually and use a box next time for storage. Anything cushioned that smells musty should probably be discarded.

7. Cleaning. The holidays are over and now you have to clean. Use a HEPA vacuum (one with a high efficiency particulate arrestance filter), which won’t spew out allergens and irritants in its exhaust stream. Avoid using fragranced cleaning products. If you have to use a spray product, spray it onto a cleaning rag rather than onto the surface, to minimize the spread of the chemical into the air. If you placed your Christmas tree over or near a hot-air register, after the tree is gone, remove the grille and clean out the duct boot.

If your child has a cold or asthma you may be tempted to operate a humidifier in his or her bedroom. But humidifiers can cause mold and indoor air quality problems.

There are four common types of portable humidifiers: ultrasonic, evaporative pad (cool mist), steam, and warm mist.

(image of a furnace humidifier with actinomycetes – (c) J. May 2008)

Ultrasonic units use ultrasonic sound energy to directly convert water into microscopic droplets. The process aerosolizes whatever is in the water, including minerals, bacteria and algae – thus distributing dust and allergens in the fog these units emit.

Evaporative pad humidifiers – those that contain a cellulose (paper mesh) pad sitting in a reservoir of water– are prone to biological contamination because the cellulose pad itself is a nutrient, and also because the pad acts as a filter, capturing house dust that contains biodegradable skin scales, lint and cornstarch from body powder.

In one family I worked with, a mother and her daughter had been suffering respiratory problems for most of that winter. The worse their symptoms became, the longer they operated their evaporative humidifier. I found high levels of actinomycetes (filamentous bacteria) in the indoor air and in the humidifier pad. The family stopped using the humidifier and gave the house a thorough cleaning. Within two weeks, the mother and daughter were nearly symptom-free. I sometimes even find Stachybotrys chartarum mold (the feared “toxic black mold”) growing on the paper pad in cool-mist humidifiers. These humidifiers are the most popular type, but because they are so prone to biological contamination, I believe that they should be banned from the marketplace.

The only portable humidifier I recommend is a warm-mist unit, which boils water and thus emits only water vapor. Minerals and other contaminants then remain behind in the water reservoir. Use only the kind of humidifier that has a humidistat, which shuts the unit off when the relative humidity in the room reaches a set point. (Old-fashioned steam humidifiers lack that kind of control and keep making steam until they run out of water, sometimes excessively elevating the relative humidity.) Lastly, place the warm-mist humidifier on a surface your children can’t reach, because when operating, the unit contains a small amount of boiling water.

Are central humidification systems preferable? In almost every furnace humidifier I’ve seen, the water tray was full of biological growth and its by-products: chemicals that mold and bacteria can create and excrete. When the water film breaks on the humidifier sponge, water droplets containing allergens are ejected from the rotating drum and become airborne. These droplets are then taken up by the air flowing through the humidifier and into the furnace supply system. When these droplets evaporate, the allergens that were within the droplets remain suspended in the airflow as particulates and move with the air through ducts into the habitable areas, where they can be inhaled. When the particulates settle out of the air onto surfaces, they can be re-aerosolized when surface dust is disturbed and again be inhaled. These allergen-containing particulates are small enough to be highly respirable (breathed deeply into the lung).
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I only recommend two types of central humidifiers: a steam-type, which boils water and injects steam into the supply airflow; or a trickle-type, which uses water flowing down a metal mesh pad and has no water reservoir to support biological growth. Any central humidifier should be checked monthly, to be sure there are no leaks and that water is not soaking into the fiberglass lining material inside the ducts or furnace, which can lead to mold growth within the system.

I do have a concern about all humidifiers, however: they introduce moisture into the air. This may feel good on your skin, but it can lead to elevated relative humidity. A number of molds commonly found indoors, including some of the most allergenic and even toxic, can flourish when the relative humidity is in excess of 75% to 80%. So whether you have central humidification or use a warm-mist portable humidifier, it’s important to measure the relative humidity with a hygrometer, available in many hardware and building supply stores. In the winter, reduce the amount of humidification if the relative humidity is in excess of 35% or if there is condensation on the walls (and the wall paper is peeling off!).

If your skin feels dry, use skin lotion – preferably one without fragrance, but that’s a topic for another article for Clever Parents.

Children play hard and get dirty, so their bodies and clothing need to be washed often. It’s also important to keep the house clean, especially the floors, where toddlers crawl and children play. Careful cleaning should reduce odors, dirt and dust, but unfortunately, the opposite is sometimes the case. For example, a conventional vacuum cleaner may spew out allergens in its exhaust, and a sponge or mop contaminated with bacterial growth can make the broom closet or surfaces you wipe stink. (image of magnified bacteria digesting skin scale on a stinky sponge – (c) J. May 2008)

Here are some tips to help you clean without “dirtying” the air.

1. Keep sponges and mops clean. Clean mop heads and sponges regularly by soaking them in a mild ammonia solution (one part ammonia to ten parts water). Sponges can also be run through a dishwasher, along with your dirty dishes.

2. Clean a smelly surface. If you wiped a counter or table with a stinky sponge, you can get rid of the smell by wiping the surface with a solution of one tablespoon of ammonia or one teaspoon of baking soda in a cup of water. (First test a spot to be sure the solution won’t damage the finish.)

3. Rags are good. Rags seem old-fashioned, but they are easily washed and dried after use.

4. Never mix ammonia and bleach. This creates chloramine – a toxic gas.

5. Use a HEPA vacuum cleaner. HEPA stands for “high efficiency particulate arrestance” and describes the filters in these machines. A HEPA filter prevents fine dust from getting into the vacuum’s exhaust air.

6. Central vacuum systems are OK too, as long as they exhaust to the exterior and not into your basement or garage.

7. Your vacuum cleaner rules. If you hire someone to clean your house, insist the person use your vacuum and not their own. Otherwise, allergens from someone else’s house may find their way into yours.

8. Bagless vacuums can be trouble. When you empty a bagless vacuum cleaner, where does some of that dust go? Into the house air, your hair and onto your clothing. If you already own a bagless vacuum cleaner, empty it outdoors.

9. Fragrances don’t fix the problem. Don’t depend on plug-in fragrance emitters or scented air sprays. They just cover up the problem, plus they introduce chemicals into your indoor air that can be irritating, particularly to children with asthma. It’s always better to remove whatever is causing the unpleasant smell.

10. Some air purifiers foul the air. Ionizing air purifiers produce ozone, a gas that may smell like fresh, outdoor air, but ozone can be irritating to breathe. Keep the surfaces in your house clean, rather than try to “clean the air.” Even if the air purifier doesn’t produce ozone, it can never clean the air of all irritants and allergens, as long as the sources of these contaminants remain in your home.

Healthy Home Tips: Cleaning Can Make Things Worse
©2008 J. May

No one wants a child crawling around on dust and grime, so we vacuum carpets and mop kitchen floors.

But what about the contaminants we can’t see, lurking in unexpected places? How do we get rid of these potential irritants and allergens, before they become airborne and we begin to sneeze, cough and wheeze?

1. A refrigerator can contaminate your kitchen air. The coils at the back or bottom can be coated with moldy dust or cat dander. If your appliance has a drip tray, it can contain bacteria, mold and yeast. Every time the appliance turns on, by-products of this growth can become airborne. Clean the coils twice a year with a HEPA (high efficiency particulate arrestance) vacuum. Use a 36-inch vacuum crevice tool to get to hard-to-reach surfaces. Wash the drip tray twice a year. If the tray is plastic, putting two tablespoons of salt in the tray will help inhibit microbial growth.

2. Radiators and baseboard convectors can be moldy. These surfaces get dusty and can even contain pet dander and mold, so should be HEPA vacuumed every year before the heat is turned on.

3. Air registers can cover all sorts of surprises. At various times when I lifted up a register to look inside a duct for a heating or cooling system, I’ve seen a half-eaten donut, cat and dog hair, an empty coffee cup, children’s toys, dog food, and of course what I usually expect to see – moldy dust. HEPA vacuum under your registers once or twice a year.

4. Don’t forget cabinet kick spaces. I’ve seen filthy, mold-covered kick spaces in houses with gleaming floors. Vacuum these hidden nooks, and twice a year, wipe them clean with a suitable household cleaner.

5. Portable humidifiers can contain mold. Use a warm-mist humidifier that boils the water and doesn’t get moldy.

6. Pets are dust mops. Long fur and hair captures dust. Keep your pet clean. If your son or daughter is allergic to pet dander, the animal should not be allowed in your child’s bedroom. Cushioned dog beds can become infested with dust mites, and then dust-mite allergens travel with the dog into your children’s laps or beds, or onto your couch. Use a folded blanket for the dog’s bed, and wash the blanket weekly.

7. Dust mites like fish tanks. Dust mites thrive in humid environments. Fish tank covers are moist and often covered with fish-food flakes: gourmet treats to a dust mite. Try not to spill fish-food flakes when you feed the fish, and keep the tank cover clean. If your child is allergic to dust mites, don’t put a fish tank in his or her bedroom.

8. Some air purifiers aren’t so pure. Ionizing air purifiers produce ozone, a gas that may smell like fresh, outdoor air, but ozone can be irritating to breathe. Keep the surfaces in your house clean, rather than try to “clean the air.”

©2008 Jeffrey C. May

Dust is home to dust mites, a pest virtually invisible to the naked eye, and one of the most common causes of allergy and asthma symptoms in the world. Dust mites thrive on our skin scales and body moisture, so they are found in beds, pillows, frequently used cushioned furniture, and even clothing. If your child has allergies or asthma, take steps to minimize the presence of dust mites, as well as other allergens, in your child’s bedroom.

1. Dust mite covers. Dust mites can travel in clothing, so if there are dust mites in one bed in your house, there are probably dust mites in most of your beds. Encase all box springs, mattresses and bed pillows with dust-mite covers. For older mattresses, use covers consisting of solid plastic (such as urethane) and woven material. Do not use covers made only from non-woven fabric.

2. Washing dust-mite covers. If you want to wash an allergen-control mattress encasing now and then, put two on the mattress and remove only the outer one. Otherwise, dust-mite allergens in the mattress will leak out and contaminate the room when you remove the mattress encasing.

3. Down on down. Down-filled quilts and pillows are often contaminated with dust mites, and emit feather fragments that can be irritating to inhale. So avoid feather bedding.

4. Quilts and blankets. To kill dust mites, put quilts and blankets in a dryer once a week for about ten minutes on medium heat, until hot.

5. Humidifiers. Use only a warm-mist humidifier, which boils the water and thus inhibits the growth of yeast, bacteria and mold.

6. Excess moisture. Dust mites and mold colonies thrive in high humidity. If you humidify your child’s room in winter, measure the relative humidity with a hygrometer, available in many building supply and hardware stores. Keep the relative humidity under 40%. (If there is still water condensing on walls or windows, don’t use the humidifier as much.)

7. Hard flooring. Carpeting captures dust and can harbor mold and dust mites, so have wood, tile or laminate floors in your allergic child’s bedroom.

8. Pets: both breathing and stuffed. If your child is allergic to pet dander, don’t let your family dog or cat into the child’s bedroom. Don’t let a neighbor who owns a cat or dog sit on your child’s bed, because dander from that pet can collect on your neighbor’s clothing. Don’t put a fish tank in your child’s bedroom. Believe it or not, mites can infest the tank cover, and the filter aerosolizes algae and other contaminants from the water. Lastly, if your child sleeps with stuffed animals, put them in a dryer once a week for ten minutes on low to medium heat, to kill dust mites.