3.0 INDOOR AIR QUALITY AND ITS CONTAMINANTS

          Types of contaminants, Where does it come from, Why is it harmful.

As explained earlier, the indoor air quality could be worse than the outdoor air quality, especially when the ventilation is poor. There are few factors that affect the quality of indoor air; such as the design and orientation of the space itself, as mentioned in the previous chapter. In the indoor spaces, contaminants are present as well. They are categorized into 3 main types- chemical, biological and physical. Contaminants enter our body through ingestion, inhalation or touch but in our case, we are discussing the main indoor pollutants which are mostly air-bone contaminants that affect humans through inhalation.

3.1     CHEMICAL CONTAMINANTS

Chemicals from furnishings and surface finishes in the interior could be the source of bad indoor air quality. These chemicals, otherwise known as Volatile Organic Compounds (VOCs); are released into the air at room temperature and can harm our health. VOCs are found in some of the most common materials such as composite wood; which includes particle board, plywood, hardwood and medium density fiberboard (MDF). All these wood are categorized as engineered wood panels or simply, “pressed wood”; made by binding together fibers of woods together with adhesives. These man-made woods are custom made which comes with specific measurements and sizes in order to match with certain international standards. Formaldehyde, commonly present in adhesives in these composite woods have been classified as carcinogens (cancer causing agents). It irritates the eyes and can cause respiratory problems such as stuffy nose, coughing and wheezing. In some cases it even can cause nausea and fatigue.

Solid wood is a good alternative for composite wood products, as it does not contain formaldehyde. A cheaper alternative is to use construction-grade plywood, which uses more stable formaldehyde glue. More stable formaldehyde glue means the formaldehyde particles present in the wood will not react to the room temperature easily because it forms a tighter bond between the particles; it is tightly bound and that prevents it to be released into the air. According to studies, the indoor air concentrations of formaldehyde are often higher than the legal tolerance value of 100 Nl l^-1 (0.1 PPM, 120 µg m^-3) formaldehyde².

Benzene, another type of VOCs can enter the indoors in the form of motor vehicle exhaust. Houses built near the main roads or highways might face problem with benzene entering the living spaces, other than noise pollution. An attached garage will increase the risk of benzene entering the home through opened doors and windows.

Having indoor plants, especially the spider plant (Chlorophytumn comosum) could help remove chemical vapor from the air, formaldehyde in particular. The plant leaves metabolize and convert formaldehyde into tissue products such as sugars, amino acids and organic acids; a process called “metabolic breakdown”.  When plants transpire water vapor (lose water) from their leaves, they pull the air around their roots which supplies their root microbes (microorganisms present on the roots) with oxygen. Besides oxygen, the root microbes also use other substances present in the surrounding air, such as toxic chemicals as source of food and energy. The microbes can rapidly adapt to chemical contaminants by producing new colonies that are resistant to the chemical. As a result, the longer they are exposed to the chemical, the more effective they are at breaking down that particular chemical.

3.2     BIOLOGICAL CONTAMINANTS

Biological contaminants are living organisms that can be hazardous to human health, such as molds, fungi, bacteria and viruses. It is concerned that having indoor plants will increase dust and mold spores in living spaces, due to the soil exposed. In fact, foliage plants (plants cultivated specifically for their ornamental leaves) will help reduce air bone microorganisms in the air provided that the soil is not exposed. At least two inches of gravel or other porous material such as stones on top of the soil will prevent mold growth. Scientific research had proven that plant-filled rooms have 50 to 60 percent less airbone microbes then similar rooms without plants. However, some allergy physicans argued that patients should remove all plants from their homes; due to the concerns that but there is no scientific basis for this recommendation. On the contrary, plants should be beneficial to all allergy patients provided the plants are grown in a manner to prevent mold growth on the soil surface as mentioned previously.

Molds generally grow in dark areas with sufficient nutrients and high moisture. High moisture levels can result from water that comes in from the outside through the floor, walls or roof; from plumbing leaks; or from moisture produced by the people living in the home through daily activities such as bathing, washing and cooking. Areas such as kitchen, bathroom, basement, garage and storerooms should be constantly checked for the presence of molds.

It is also encouraged to measure the moisture level in the air to prevent mold growth and other health problems. A hygrometer, available from hardware stores is needed to find the relative humidity in living homes. Recommended indoor relative humidity is 30 % to 50 %.  It is not difficult to detect mold: the discolouration and the smell. Often, a musty or earthy smell indicates the presence of molds. But even if we do not notice discolourations or smells, dampness are indications of moisture problems that will probably cause mold growth.

In addition to the damage mold can do to our walls, and fabrics, molds growing inside the home can cause health problems because they release spores and chemicals that can be toxic and irritating. The health effects of mold can range from being insignificant to causing allergic reactions and even chronic illness, such as environmental sensitivities; depending on the type of mold present, the amount and degree of exposure, and the health condition of the occupants. Therefore any sign of mold in the home should be taken seriously and the mold should be removed as soon as possible.

Besides mold, bacteria and viruses in homes can cause serious health problems to human beings. One of the carrier of bacteria and viruses is pets in homes. Pets are living organisms and therefore will shed dead skin flakes and hair; produce urine, faeces and saliva. The particles or microorganisms from their waste products linger on carpets, furniture, floors and walls at home. In the case of individuals with allergies like asthma and skin diseases, having pet in homes is actually a very serious offence. Therefore it is advisable to keep indoor living area a pet-free zone to avoid allergy responses and also for hygiene purposes.

3.2     PHYSICAL CONTAMINANTS

Radon is a naturally occurring radioactive gas which is produced from the decay of radium. It Is generally found in rocks, soils, and underground water. Traces of radon could enter a building through foundation cracks, floor drains, joints between basement walls and floors and so on.  Although there are no immediate health effects, long-term exposure to radon could cause lung cancer; It is the number one cause of lung cancer among non-smokers. The Environmental Protection Agency and the Surgeon General recommend that all homes should test their radon levels below the third floor, due to its fatal consequences. The average radon level is 1.3 picocuries per liter (pCi/L); it is suggested that action to be taken if the radon level is above 4 picocuries per liter.