We often think of air pollution as the risk we face outside, but indoor air can also be polluted. However, vapors, smoke, mold, and different chemicals ( VOC’s) used in some furnishings, paints, and cleaners can affect indoor air quality (IAQ) and our health.
In the past several years, accumulating scientific evidence suggests that the air within our homes and other buildings is more polluted than outdoors. Other research reveals that most people spend about 90% of their time indoors. Thus, the risk to health might be greater due to exposure to polluted indoor air.
Additionally, people who get exposed to polluted indoor air for an extended period are often more susceptible to the impact of air pollution. These people include elderly individuals, young people, and chronically ill people, particularly those suffering from cardiovascular or respiratory disease.
Although the pollution levels from each source may not pose a considerable health risk, most homes have multiple sources of air pollution. Thus, there is a serious risk from the cumulative impact of the pollution sources. Fortunately, there are specific steps you can take to reduce the risk from the existing pollution sources and prevent further pollution.
Causes of Indoor Air Problems.
There are different pollution sources that release particles or gasses into their air, often cause indoor air quality in residential and commercial properties. Insufficient ventilation can increase pollutant levels. This is because insufficient ventilation means there is insufficient outdoor air entering the home to dilute emissions from indoor pollution sources. High humidity levels and temperatures can also increase the concentration of some pollutants.
Indoor pollutants
There are many indoor air pollution sources in any home. These sources of indoor air pollution fall under the following categories;
- Combustion sources such as kerosene, wood, coal, oil, gas, and tobacco products
- Products for household cleaning & maintenance, hobbies, and personal care
- Building materials & furnishings that have deteriorated
- Asbestos-containing insulation
- Damp or wet carpet
- Radon escaping from the ground via an insufficiently sealed basement slab
- Cabinetry or furniture made of various wood products
- PM 2.5 particles from cooking
- Random outdoor sources such as pesticides, traffic pollution and factories
Note that the relative importance of any source of indoor air pollution depends on how much of a specific pollutant it generates and how dangerous those emissions are. In some instances, factors such as the period the pollution source has been there and whether it’s maintained are worth considering. For example, an improperly adjusted gas stove might emit more carbon monoxide than a properly installed and adjusted gas stove, however depending on the amount of use and ventilation it may be of lesser concern..
Some pollution sources, such as furnishings, building materials, and household products, such as air fresheners, are likely to release pollutants more or less continuously.
There are also other indoor air pollution sources related to common activities carried out in homes. These sources are likely to release pollutants intermittently. These sources include faulty stoves, space heaters, or furnaces. The use of paint strippers during redecoration, solvents in cleaning, and smoking fall under this category.
Ventilation
If limited outdoor air is entering your home, pollutants can quickly accumulate to levels that create discomfort and pose a health risk. Unless homes are built with a well designed mechanical ventilation system, that bring in fresh air and dilute the polluted air, the noxious pollutants accumulate.
So, how does Outdoor Air enter a Home?
Generally, outdoor air enters and leaves the home by natural ventilation, infiltration, and mechanical ventilation. Infiltration involves air flowing into a building through openings, and cracks in the walls, joints, ceilings, and floors. Generally where there is infiltration in the lower parts of the house, there is what is termed exfiltration in the roof/ ceilings on the upper floors. Natural ventilation can be provided by windows particularly in the shoulder seasons letting fresher outdoor air into the home.
Mechanical ventilation can “spot” ventilate i.e. remove air from a single room such as the kitchen or bathroom. Whole house air handling systems utilize a fan and duct work to continuously remove air and distribute filtered and conditioned air (from outdoors) to strategic areas in the home. HRV’s or ERV’s are purpose built for this function.
The rate at which the outdoor air replaces the indoor air is referred to as the air exchange rate. Building codes set out mandatory ventilation for newly built homes.
As a homeowner, having a working understanding of air quality and what affects it is essential to keep your home healthy and fresh. Taking the appropriate action to improve the overall indoor air quality by eliminating the sources of indoor air pollution, altering your activities to reduce pollution, employing a filtration and fresh air system and opening windows ( when appropriate) to increase ventilation temporarily are all essential parts of having optimal IAQ.
FAQs
What causes indoor air problems?
Insufficient ventilation can increase pollutant levels. fresh air introduced into a home is essential to dilute emissions from indoor pollution sources. High humidity levels and temperatures can also increase the concentration of some pollutants.
Does ventilation affect indoor air quality?
Yes. If limited outdoor air is entering your home, pollutants can quickly accumulate to levels that create discomfort and pose a health risk. Again ensure sufficient outdoor air is being introduced into the home to dilute pollutants. Spot ventilation ( fans) can get rid of pollutants at the source. These measures, along with good filtration can provide good IAQ
How does outdoor air enter your home?
Outdoor air enters and leaves the home through natural ventilation, infiltration, and mechanical ventilation. Infiltration involves air flowing into a building through various openings, and cracks in the walls, joints, ceilings, and floors. Natural ventilation via open windows can be limited by weather. Mechanical ventilation is reliable and predictable and can be controlled easily by the home owner.
