Another hot muggy dusty summer is just around the corner. The grass is growing, the trees are budding and pollen is flying. Summertime in Ottawa is a beautiful season to enjoy outdoor fun with healthy activities. Indoors, conditions are not always so carefree.
Typically warm summer temperatures are the perfect opportunity to naturally ventilate our indoor environment. Open doors and windows, in order to dilute wintertime’s residue of dust mites and bio effluent accumulation from carpets and fixtures. Get a healthy dose of fresh air. It seems all these things are generally good for indoor air quality. However, take a moment to reflect on what may happen during summer's ventilation exuberance.
Pollen Dust and allergies.
Consider the allergy sufferer who lives with you. At peak pollen season, is it wise to open windows (screens stop bugs, not pollen and dust) or should we air condition and filter the air with a good quality High Efficiency Particulates Arrestor (HEPA) furnace filter?
Air can be contaminated by a range of very different particles such as dust, pollen, soot, smoke and mold spores. Many of them can harm our health, especially very small particles that can enter deep into the lungs. What is known about the different health effects of particles?
Respirable suspended particulates (R.S.P.) can be common house dust, mold spores, pollen or construction dust. To the allergy sufferer, and irritating RSP condition may affect them indoors or outside the house. It is impossible to control outdoor (ambient) dust conditions, however it is completely possible to reduce dust in a controlled air filtered, dry indoor environment.
The aerodynamic properties of particles determine how they are transported through the air and how they can be removed from it. These properties also govern how far they get into the air passages of the respiratory system.
Modern HEPA filters added to your existing furnace (move the furnace fan control from “auto” to “on”) reduce airborne particles and reduce household R.S.P. Low voltage electrostatic furnace filters can be fitted to most furnaces and cost between $115.00 to $350.00. The installation of these types of filters is quite simple.
Basement – Moisture Controlled
If we rely on natural ventilation all summer long, how do we control lower basement level humidity? Hot muggy summer weather conditions generate moisture on cool indoor surfaces. Cooler surfaces in the mid-July are generally found on basement floors and wall assemblies.
The summer ambient relative humidity levels are very hight. To illustrate, think of a cool frosty beer taken out of the fridge. The moment the cool beer bottle is placed on the picnic table it begins to sweat or moisture begins to condense on the beer bottle surface. The beer in the fridge was in a dry cool environment. The same beer on my patio is in a warm, high relative humidity environment. When the warm moist air touches the cool bottle surface the drop in the bottle surface temperature condenses the moisture because cool temperatures hold less moisture than warm temperatures. If my fridge is set at 1°c and the exterior humidex is 85% the beer will condense as soon as it is exposed to the outdoor air.
Now while I enjoy my beer on my rear deck I realize my basement windows are open to get rid of the “musty basement smell”. No, no, no if the previously mentioned outdoor relative humidity is 85% and this warm afternoon picnic temperature reaches 32°c (common Ottawa conditions). Then I am creating condensation on all my cool basement floor and wall cavity surfaces that are 30°c or cooler. Just as the cool beer bottle condenses moisture on the cool glass surface, most basement slab surfaces I've tested don't get warmer than 25°c in mid-summer.
Everything that is organic (wood, paper, cotton, carpets with deposits of skin cells and dander) that comes in contact with this condensed moisture provides and ideal environment for mold growth which contributes to my “musty basement smell”.
During peak pollen, high humidity / temperature days it may be better to close your windows, turn on your air conditioner, filter the air and dry out the your basement instead of opening your lower level windows.
Rising electricity costs make this option less desirable. More efficient air conditioning with a high SEER (Seasonal Energy Efficiency Ratio) rating can reduce these increased expenses. Another option is to install a 50-pint Energy Guide (Enerstar) rated dehumidifier to control basement humidity during summer-peak hot / humid periods. Ventilation is still a great way to improve indoor air quality. However, understanding the best time to naturally ventilate may limit your home indoor air quality concerns. Knowing when to reduce lower level ventilation may control unnecessary moisture accumulation in your basement.
So remember a frosty beer on your patio is good. A sweaty basement wall and floor assembly is bad.
Have a healthy summer.
Whew… we survived. The perils of Old Man Winter are behind us. Or are they…” Early deep record snowfalls, little or no ground frost and warm spring sunshine are recipes for flooded basements, leaking foundations and moist concrete floors. Is your home prepared for a moist spring and damp summer? Have you removed all the leftover cardboard boxes and winter accumulated junk from your basement?
Every season, spring arrives, melts the snow, and fills our ditches and streams with high water for a week or two. Snow piled against the house disappears and we begin to store our snow blowers and shovels. Our thoughts begin to drift off to scenes of summer sunshine and outdoor activities. Typically, the city storm water management system (storm sewers, gutters, catch basins and ditches) carry away the winter run-off with few floods or household calamities. This season, heavy snow loads and shallow frost will place our homes in more peril.
Larger water run-off volume and higher ground water tables will mean more wet basements and busy sump pumps. Larger snow banks against our foundations add to ground source moisture content which builds vapor pressure against our foundation walls. The earth around our foundations that drains slowly, tends to draw moisture into our homes (Mother Nature tends to flow from hight to low, moist to dry and warm to cold).
Shallow winter frost typically affects the amount of moisture the earth can absorb before the snow melts and drains water away from our foundations. More moisture in the ground around our homes increases the water table under our footings and floor drains. City homes are connected to the city storm water management system by a perforated drainage pipe (weeping tile or Big “O”) that rests on the outside of the foundation wall, level with the underside of the footing under 8″ of 3/4 clear gravel. Ground sources of moisture, rainfall from the roof and surface drainage water is meant to drain down the foundation wall, work throught the clear gravel, enter the perforated 4″ drainage or weeping tile, then migrate by gravity around your house to the city storm connection and enter the storm water management system. Wow lots of stuff has to happen to keep water out of your basement.
Rural households are not any better off. A typical rural home without connections to the city S.W.M.S. (storm water management system) drains the Big “O” to a hole cut into the basement floor (sump pit). This sump pit services all the home's required needs for lower level drainage. Floor drains, condensation pumps, water softeners, air conditioning drains and the entire weeping tile are discharged into this pit to be electronically pumped to a buried pipe exhausting to the ditch at the end of the lane way. Let’s not begin to talk about heavy March/April snow melts, when the power goes out to these folks.
We can protect the durability and environment of our home if we control our household moisture. Active water leaks or high relative humidity in our environment can create conditions that foster poor air quality. Health Canada recommends that homes have a relative humidity between 35% and 45%. Dust mite populations increase in moist environments, especially in older carpeting on concrete basement floors. Microbiological organisms, such as fungi and bacteria, thrive in moist damp environments. Moisture and cellulose (wood, cardboard boxes, paper goods) are the perfect combination for fungal activity. It doesn’t take long for these areas to become musty, smelly and unhealthy.
We can avoid these unhealthy situations if we isolate the moisture sources and remove opportunities for bacterial and fungal contamination. The following steps will make a difference.
Indoor air quality conditions can be improved with proactive household maintenance. Anticipate moist conditions, inspect all pumps and drains, ensure ventilation and dehumidification, and store items off the floor. Your healthy environment literally begins at home. Put a spring into your step and into your healthy dry home.
The current meteoric rise in public concern and interest regarding air quality and healthy environments has created an opportunity for industry to market and promote a myriad of diverse products and services. Everything from scented candles and snake oils to ozone generators and air fresheners are being advertised as the air quality answer to all our healthy home needs.
On average, Canadians spend 80% of time indoors; a great deal of that time is spent in our homes. Controlling the air quality conditions of our work places can be difficult, however improving the home environment simply requires a basic understanding of how the home works. Universally, homes behave as an integrated system: what happens in the basement affects air quality upstairs.
The definition of a healthy home is not about having more. It is about living with less: less humidity and moisture, less chemical, and odours, less particulates and dust. Reducing air quality concerns at home means living with less irritants our bodies’ defense systems must address. Imagine if we were born with a “wheel barrel for environmental sensitivities”. Throughout our lives each person loads their wheel barrel at a different pace (Environmental Exposure). Some people have the capacity to fill a larger wheel barrel of environmental sensitivities (Dose Response). Due to past environmental exposure, other people may not have room in their wheel barrel and may have difficulty handling the environmental burden (Multiple Chemical Sensitivity). The fundamental similarity between all wheel barrels is the universal benefit of environmental load reduction. We must seize every opportunity to reduce air quality and environmental irritants from our homes in an effort to keep our wheel barrel of sensitivities empty. If our environmental load is light, our capacity to shoulder unforeseen air quality exposures is increased.
If we are to adopt the “less load” philosophy to our own homes we must embrace some lifestyle changes that promote healthy environments. We must be able to recognize the conditions that generate poor air quality and we must take the correct steps to improve them. Recognizing these conditions of poor air quality is the first step to improving your environment.
Air quality issues can be divided into two main categories: chemical and biological. Chemical air quality concerns are introduced into your environment typically by the “offgassing” of manufactured products and materials, cleaners, new furniture, construction materials, solvents, dry cleaning, air fresheners, and by-products of combustion. Biological contaminants are generated within the building environment, such as skin cells and fragments, pet dander, dust mites, pollen, bacterial mold and viruses. These types of contaminants thrive in moist, damp environments. By controlling the humidity levels in most homes, the growth of some of these culprits can be minimized.
Once a homeowner has identified potential indoor air quality contaminants in the home, a lifestyle change is required to remove them and subsequently reduce the burden on our personal wheel barrel of environmental sensitivities. We should take every opportunity to reduce exposure to both biological and chemical loads present in our living environments. This load reduction is not completed overnight. Instead, our lifestyle change should incorporate the”less is best” philosophy on a daily basis.
There are four strategies to achieve this change: isolation, separation, ventilation and filtration. The daily application of these strategies will reduce exposure to air quality contaminants, minimize the strain on each person’s wheel barrel of environmental sensitivities, and create a healthier environment.
“Isolation” is a strategy where the term "source control" applies. If we can identify a situation in the home contributing to poor air quality, the isolation strategy requires complete removal of that condition. For instance, if we’re storing a box containing moldy books, discard them. If we have a leaking pipe adding moisture to our environment, repair it.
“Separation” strategy may be storing strong or foul smelling items in a sealed container. This contains and separates off-gassing or odorous items from the rest of the home. Items such as solvents, cleaners, and paint cans can be stored in a sealed plastic container for future use. Another example of separation is the use of waterproof membranes within the house foundation to prevent moisture or dampness from entering through the exterior walls.
“Ventilation” strategy, which means an exchange of interior air with exterior air, refers to the three types available to most homes. This strategy is a means of diluting the higher concentrations of airborne contaminants and moisture generated inside the living environment. Imagine our home represents a sealed glass aquarium that we inhabit. Inside this aquarium is a constant sandstorm of very small particles we breathe (Respirable Suspended Particulate, -RSP). If we were to create an opening on one side of the aquarium and let fresh clean air in, and we were to place an exhaust fan on the other side of the aquarium blowing out, we would eventually dilute and exhaust the higher levels of RSP found inside the aquarium. This example is how we should perceive the benefits and necessity of a sound ventilation strategy in our own homes.
Effective ventilation can be achieved in three ways. The first is simply to open the windows and introduce fresh air. This is an excellent, easy method of achieving air dilution and air exchange. During cooler months, leaving windows open is no longer reasonable. We now must begin to depend on mechanical means of ventilation. The second means of ventilation relies on “exhaust only” approach to aid exchange. Range hoods and bathroom fans mechanically exhaust air contaminants from inside the home to outside through the fan mechanism. This exhaust only fan system creates less air in the home and develops a slight negative pressure to the living environment. Fresh air is re-introduced into the home throught cracks around windows, doors, the foundation and ceiling. This type of exhaust-only ventilation is the most common. New homes have building code standards that govern the size of exhaust-only devices when installed as the principle means of ventilation. Lastly, the whole house ventilation system is an integrated system of balanced filtered air in and balanced air out, creating no pressure differential with the home. These systems can be installed with “heat recovery” technology (HRV) to save the warm air from being exhausted. All three types of ventilation systems perform the same function; to remove airborne contaminants from inside the home environment, and to dilute the interior air through an exchange with outside air.
The fourth and final air quality improvement strategy should be the use of air filtration. Mechanically forcing household air through a quality furnace filter or filter media device serves the purpose of removing or entrapping airborne particles. Forced air furnace systems are an ideal way to filter household air on a continuous basis. Switch the furnace fan operation from “Auto” to “On” and have the furnace fan run continuously with a quality filter on your forced air furnace. If you do not have a forced air furnace, a stand alone HEPA (High Efficiency Particulate Arrestor) filtration device may help.
Although these air quality and healthy home recommendations may seem overwhelming, once you embraced your healthy home lifestyle changes, the benefits are noticed immediately. Efforts should be made to reduce your environment exposure load and ventilate your home at every convenient opportunity. If you “isolate” moisture and remove the sources you are aware of, if you “separate” moisture and off-gassing chemical-based products; if you ventilate and dilute air quality conditions at every opportunity; and if you filter or scrub the home’s air continuously, you will live in a much healthier environment.
A great source of healthy home and air quality information can be obtained from the Canada Mortgage and Housing Corporation (CMHC) library located at 700 Montreal Road, Ottawa, Ontario or at their website: www.cmhc-schl.gc.ca.
Shawn Rankin is an accredited Indoor Air Quality Investigator, an Indoor Environmentalist, and Heating, Ventilation & Air Conditioning (HVAC) Designer, and recognized by the CMHC as a Healthy Home Builder and Designer. He lectures for the “The Healthy Home Academy”.
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