Indoor air quality

Everyday, we face many risks to our health. Engaging in sports, driving cars, and being exposed to environmental pollutants all pose different levels of risk. Some risks are inevitable, while some others are necessary. But, there are also risks that we can choose to control and avoid, given enough information. Indoor air pollution is one risk which we can be in control of.

Over the past several years, more scientific evidence has shown that the air within homes and buildings can be much more polluted than the outdoor air. This is true even in the largest and most industrialized cities. So, when most people spend approximately 90 percent of their time indoors, the risks to health becomes much greater than we would expect.

People who are exposed to indoor air pollutants for long periods of time are very much susceptible to the effects of indoor air pollution. Such groups include the young, the elderly, and the chronically ill. And this is especially true for those with respiratory or cardiovascular problems.

The primary cause of indoor air quality is from sources that release gases or particles into the air constantly. The secondary cause would be the lack of adequate ventilation. Without proper and sufficient ventilation, indoor pollutant levels will rise. There is just not enough outdoor air brought in to dilute emissions from indoor sources and not enough indoor air pollutants is brought out of the home.

There are 3 key pollutant categories:

• Biological contaminants
  Under this category, there are bacteria, viruses, fungi, moulds, dust mites, animal dander, pollen, inadequate humidity control, water spills, stagnant water, etc.


• Chemical contaminants
  Tobacco smoke, emission from building materials and products like furniture, wall coverings, carpets, cleaning and maintenance products like detergent, insecticides and air fresheners, personal care products like hair spray and shower gel, solvents used in hobbies, air conditioning systems, humidification equipment, and other gases from combustion.


• Particles
  Particles would be substances that are suspended in the air. Particles can be solid or liquid. The size of the largest particles can be easily seen by the naked eyes. However, the more harmful particles are usually those that cannot be seen. Particles of dust, dirt or other substances can be from outside, or it could be from activities like smoking, printing and using equipment like the vacuum cleaner.

Ventilation can simply be described as admitting fresh air to replace stale or noxious air. In a particular house or office, there are 3 ways in which this can be achieved: infiltration, natural ventilation and mechanical ventilation.

Infiltration is a process when outdoor air flows into the house or office through openings, joints and cracks in the walls, floors, ceilings and around windows and doors. For natural ventilation, air moves through windows and doors that are opened. Both infiltration and natural ventilation can arise due to the difference in temperature and wind. And of course, mechanical ventilation is when devices like exhaust fans, air conditioner and electric fans are used to allow the exchange of indoor and outdoor air.

When discussing about indoor air quality, one of the most important factors is ventilation. When there is insufficient infiltration, natural ventilation or mechanical ventilation, pollutants can accumulate to levels that may cause serious health problems.

Indoor air quality affects the health of the occupants. The harmful health effects caused by indoor air pollutants may be experienced immediately, soon after or years after exposure.

Immediate effects would include headaches, dizziness, eyes, nose and throat irritation, and fatigue. Such effects are most often treatable and are usually short-termed. Other symptoms of diseases, like asthma, can also be noticeable soon after the initial exposure to indoor air pollutants. The problem with these immediate effects is that they are similar to symptoms of colds, influenza or other viral diseases. So it could be a challenge to identify if the effects are due to poor indoor air quality. The best solution is to monitor when and where the symptoms appear. If the symptoms stop or diminish when the affected person is away from the home (or office), and returns when the person comes back, it is most likely that some indoor pollutants are causing the effects.

Long term health effects could show up years after exposure or only after long and repeated periods of exposure. These effects include some respiratory diseases, heart disease, and cancer and they can be fatal. For this reason, it is very important to improve the indoor air quality in your home or office even if there are no noticeable symptoms.

People have varied health conditions at any point in time and would react very differently when exposed to the same indoor air pollutants. In addition, there is no concrete evidence indicating what concentrations of pollutants or periods of exposure will produce certain harmful effects. So, before further research could yield some definite answers, taking steps to improve the indoor air quality is probably the best solution.

There are industrial equipments that can give indication of the indoor air quality. However, a simpler way to assess indoor air quality is to take note of health effects, identify potential pollutant sources, be aware of the indoor lifestyle and activities, and to look out for ventilation problems.

When health symptoms appear after refurnishing or renovating the home or office, or spraying of insecticides, it could mean that there are some problems with the indoor air quality. Identifying potential pollutant sources is another important part in identifying indoor air quality problems. Knowing the sources of pollutants will help in assessing the indoor air quality, even though the presence of such sources may not mean there is an air quality problem. The lifestyle and activities indoor can also indicate the quality of indoor air. Activities like using hairspray, solvents for hobbies, etc. are major sources for pollutants. Ventilation problems are another area to take note of in identifying indoor air quality issues. Look out for condensation on walls, dirty air-conditioning systems, moldy shoes, stuffy air, etc. These are signs that may indicate poor ventilation.

There are 3 main strategies to tackle the indoor air quality problems we face. We should control the sources of indoor air pollutants, improve ventilation and deploy some methods to clean air.

• Source control
Eliminating, individual pollutant sources, is probably one of the most effective way to improve indoor air quality. Some sources, like those that contain asbestos, can be sealed or enclosed; others, like gas stoves, can be adjusted to decrease the amount of emissions. In many cases, source control is also a more cost-efficient approach to protecting indoor air quality than increasing ventilation because increasing ventilation can increase energy costs. Specific sources of indoor air pollution in your home are listed later in this section.
• Ventilation improvement
Another approach to lowering the concentrations of indoor air pollutants in your home or office is to increase the amount of outdoor air coming indoors. Most cooling systems do not mechanically bring fresh air indoors. Opening windows and doors, operating window or attic fans, when the weather permits, or running a window air conditioner with the vent control open increases the outdoor ventilation rate. Local exhaust fans remove contaminants directly from the room where the fan is located and also increase the outdoor air ventilation rate.

It is particularly important to take as many of these steps as possible while you are involved in short-term activities that can generate high levels of pollutants--for example, painting, paint stripping, heating with kerosene heaters, cooking, or engaging in maintenance and hobby activities such as welding, soldering, or sanding. You might also choose to do some of these activities outdoors, if you can and if weather permits.

Advanced designs of new homes and offices are starting to feature mechanical systems that bring outdoor air into the home. Some of these designs include energy-efficient heat recovery ventilators (also known as air-to-air heat exchangers).

• Methods in cleaning air
Air can be cleaned in many ways. One way is to deploy electric air cleaners. Air cleaners come in various types and sizes, and their prices range from relatively low-priced desktop models to highly complicated and expensive systems. The effectiveness of any air cleaner is dependent on how well it can collect pollutants. But we need to bear in mind that air cleaners are generally not designed and do not have the capabilities to remove gaseous pollutants. Proper maintenance of these equipments is also required to ensure performance is a long run.

Another way to clean indoor air, with today's advancement in technology, is to treat the interior of the house or office with Titanium Dioxide photocatalyst. Titanium dioxide, being a very strong oxidizing agent in the presence of light, can quickly break down any organic pollutants (gaseous or otherwise) to harmless carbon dioxide and water vapour. Using photocatalyst, it means there is no maintenance to be done. Once the photocatalyst is coated on the walls and ceilings, it will start working immediately in the presence of light.

For most indoor air quality problems in the home or office, source control is the most effective solution. However, we understand that some sources are inherent in the furniture, furnishings, and indoor activities that need to be carried out. So, a good ventilation system will help improve the indoor air quality. To complement any good ventilation system, we can use different methods available to clean the air. When all these steps are diligently carried out, we will minimize the risk of bad health effects in any indoor environment.