ACTIVATED CARBON or AC

Activated carbon is the generic term used to describe a family of carbonaceous adsorbents with a highly crystalline form and extensively developed internal pore structure. Activation creates a fast internal pore network and imparts certain surface chemistries (functional groups) inside each particle. Thus activation gives carbon its unique filtering characteristics.

ASBESTOS

While asbestos products have been banned in Australia, pre-existing use of these materials can result in asbestos fibre in indoor air. Asbestos building materials were widely used in commercial and industrial buildings in Australia. The main indoor sources are exposed and deteriorating insulation materials and unsealed or fraying building wall and ceiling asbestos cement surfaces. Asbestos fibres, when respired, can cause asbestosis (a lung disease) and mesothelioma (tumours in the lungs, heart or abdomen). There is no indoor health goal for asbestos.

Studies have shown that levels in buildings in Australia are well below levels at which health effects could be expected. Provided existing surfaces are not subject to severe deterioration, indoor levels will remain low. Codes to minimise the risk of exposure to fibres during the removal or renovation of these products in existing buildings are in place.

BACTERIA

Bacteria also occur in damp humid conditions. Outbreaks of the Legionella bacteria, for example, have most commonly been associated with contaminated drift from air-conditioning cooling towers entering the building via the air conditioning system. Legionella has also been associated with spa pools, composted animal manures, composted vegetable and plant material and commercial potting mixes. The bacteria are commonly found in low numbers in soil and water, but can multiply rapidly in warm, moist environments (SoEAC 1996). Infection with the Legionella bacteria can result in a pneumonia-like lung infection and impaired kidney function. The fatality rate from Legionella is approximately 15%. Between 1991 and 1994 there were 251 notifications of legionnaire’s disease in NSW, an incidence rate of 4.2 per 100,000 people (SoEAC 1996).

Although there are no goals for bacteria concentrations in indoor environments, some controls do exist. Australian Standards (AS3666-1989 and ASNZ3666-1995) which address the maintenance of air conditioning systems have been developed in an effort to control the incidence of Legionella. State legislation such as the NSW Public Health Act (No.10, 1991, Part 4-Microbial control) and associated regulation (Part 6, Microbial control) also address this issue.

CADR

Although there is no universally accepted method for comparing air-cleaning devices, several investigators of portable air-cleaning units have expressed their results as a ”Clean Air Delivery Rate” or CADR. The CADR is the product of the unit efficiency and the airflow rate, and is a measure of the number of CFM of air it cleans of a specific material.

CARBON

Carbon, the sixth most abundant element in the universe, has been known since ancient times. Many natural substances of base materials are used to make carbon. The most common of these are wood, coal, lignite, and coconut shell. Amorphous carbon is formed when a material containing carbon is burned without enough oxygen for it to burn completely.

PRE FILTER

A pre filter is the primary layer of filtration that collects large particles before they reach the HEPA filter. Eliminating these larger particles, dust and hair extends the life of your HEPA filter. Occasional vacuuming of the exterior of the unit will help extend life of the filters. Frequent pre filter changes will also prolong the HEPA filter life.

PRECIPATATOR

There are many simple electronic devices that claim to clean the air in your home by making negative ions and ozone. The claim is accurate–they do make both ozone and negative ions, and they do clean the air in your home. However, that’s not the whole story. First, ozone may have the “fresh” smell that occurs after a thunderstorm (a potent producer of ozone), but ozone is a powerful oxidizing agent and chemical irritant that’s considered an environmental pollutant rather than a charming scent. The manufacturers are taking a nuisance effect and touting it as a “valuable feature.” Second, the negative charges emitted by these electronic devices attach themselves to dust, ash, pollen, and smoke particles and cause those particles to bind themselves to your walls and furniture. The air really does become cleaner, but every surface in your home becomes dirtier as a result.

MICRONS

A micron is a unit of length equal to 1 millionth of a meter or .000039th (39 millionth) of an inch. Another name for micron is micrometer.

MOULD SPORES

Moulds produce tiny spores to reproduce, just as plants produce seeds. Mould spores waft through the indoor and outdoor air continually. When mould spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. There are moulds that can grow on wood, paper, carpet, and foods. When excessive moisture or water accumulates indoors, mould growth will often occur, particularly if the moisture problem remains undiscovered or unaddressed. Moulds can trigger asthma episodes in individuals with an allergic reaction to mould. High performance air filters can easily remove these dangerous pathogens

OZONE

Ozone, a lung irritant, is produced indirectly by ion generators and some other electronic air cleaners and directly by ozone generators. While indirect ozone production is of concern, there is even greater concern with the direct, and purposeful introduction of a lung irritant into indoor air. There is no difference, despite some marketers’ claims, between ozone in smog outdoors and ozone produced by these devices. Repeated exposure to ozone pollution may cause permanent damage to the lungs. Even when ozone is present in low levels, inhaling it triggers a variety of health problems including chest pains, coughing, nausea, throat irritation, and congestion. It also can worsen bronchitis, heart disease, emphysema, and asthma, and reduce lung capacity.

PARTICLE COUNT

A standard developed for measuring particulate matter in a pre defined area.

PM10

Particulate Matter Up to 10 Microns in Diameter (PM10)
The number 10 refers to the particle size measured in microns.
PM 10’s are widely considered the most dangerous to human health. Efficient air filtration systems can remove over 99% of particles down to PM 0.3

FORMALDEHYDE

The most common sources of formaldehyde are building and furnishing materials including insulating materials, pressed wood products such as chipboard and plywood, and some fabrics and carpets. Emissions from these products are generally greater when new. If not well cured, these products can continue to emit formaldehyde for long periods. Levels of emissions in existing houses can become elevated after renovation. The introduction of new production techniques has substantially reduced emissions by Australian made products, however this may not be the case with some imported materials. Formaldehyde is also emitted by gas stoves and tobacco smoke. Formaldehyde can cause irritation of the respiratory tract, wheezing and coughing, fatigue, skin rash and severe allergic reactions, and is a suspected carcinogen.

Formaldehyde levels seldom exceed the NHMRC goal of 0.1 ppm in conventional dwellings and other buildings. However, in new dwellings, mobile homes, mobile offices and caravans, where use of source materials is often extensive, levels above the NHMRC goal can occur frequently. In new mobile buildings and caravans the concentrations of formaldehyde can exceed the NHMRC goal for several years. In buildings insulated with urea-formaldehyde foam insulation, (seldom used in Australia) levels of up to ten times the goal have been recorded soon after installation although after several months these generally declined to below the goal (Brown 1991).

FUNGI

Fungi such as moulds and yeast are common in damp humid conditions within buildings particularly in bathrooms, laundries and air conditioning systems. Modern building construction and design make new houses more airtight and there is a tendency for an increased number of bathrooms and internal laundries. It is increasingly common for houses to be left closed up for long periods of the day. These trends have resulted in the increasing prevalence of the humid conditions suitable for the growth of these organisms.

There has been very little research into the impact of fungi on indoor air quality although it is known that they can cause inflammation and trigger allergic reactions. There is no goal for fungi concentrations in indoor environments. A study of 40 dwellings in Victoria found 75% had indoor mould growth and a third of those had viable mould concentrations above 2,000 colony forming units (CFU)/m3 (Godish et al. 1993). Around 13% had levels above 10,000 CFU/m3. Other studies found much lower levels with median levels ranging from 500-1,150 CFU/m3 while concentrations in office buildings have been found to reach 2,500 CFU/m3 but mainly range between 200-1,500 CFU/m3 (Brown 1997).

GAS ADSORPTION

When a gas or vapor is brought into contact with a solid, the solid takes up part of it. The molecules that disappear from the gas either enter the inside of the solid, or remain on the outside attached to the surface. The former phenomenon is termed absorption (or dissolution) and the latter adsorption.

HEPA Filter

HEPA stands for High Efficiency Particulate Arrested Filter, and like the name says, these filters are designed to remove 99.97% of all airborne pollutants 0.3 microns or larger from the air that passes through the filter (these include tobacco smoke, household dust and pollen).

IONISER

Ion generators act by charging the particles in a room so that they are attracted to walls, floors, tabletops, draperies, occupants, etc. Abrasion can result in these particles being re-suspended into the air. In some cases these devices contain a collector to attract the charged particles back to the unit. While ion generators may remove small particles (e.g., those in tobacco smoke) from the indoor air, they do not remove gases or odors, and may be relatively ineffective in removing large particles such as pollen and house dust allergens. Although some have suggested that these devices provide a benefit by rectifying a hypothesized ion imbalance, no controlled studies have confirmed this effect.

HOUSE DUST MITES

House dust mites live in carpets, bedclothes and furnishings, consuming shed human skin. Mites, or more specifically their faeces, are a major source of the allergens found in house dust.

Dust mites can cause respiratory impairment, especially in those suffering from asthma or hay fever. There is no goal for dust mites, but mean allergen levels above 2 µg/g in fine dust (equivalent to 100 mites per gram) may increase the risk of sensitisation and of symptoms while levels exceeding 10 µg/g (500 mites per gram) increase the risk of acute or severe asthma attacks (SoEAC 1996).

House dust mites are prevalent in Australia, with levels, particularly in warm humid areas such as coastal NSW, believed to be among the highest in the world. Mean allergen levels in the range of 10-40 µg/g are commonly found in dwellings in coastal areas of Australia (Tovey 1992). The high incidence of asthma in Australia, with approximately 5% of adults and 15% of children suffering from the condition, make the incidence of house dust mites an important environmental concern.

LEAD

Lead levels in indoor air are generally low, with the main source being flaking of paints with high lead content. These paints were in extensive use prior to 1970 and pose a particular risk during the renovation of older houses. Flakes from deteriorating painted surfaces can be ingested, particularly by young children, and dust generated by sanding operations or from disturbance of dust in roof cavities can be respired. Lead can also be introduced into indoor air by infiltration of air contaminated by lead from motor vehicle emissions and in areas close to some lead-based industries (see Illawarra Case Study).

Exposure to lead is associated with a decrease in IQ levels in preschool children which can result in learning and behavioural difficulties. Elevated blood lead levels are also associated with a range of health problems in adults, including hypertension. The NHMRC goal for lead in air is a 3-month average of 1.5 µg/m3. There is insufficient data to determine typical lead levels in indoor air in NSW (see also section 2.13).

MICRONS

A micron is a unit of length equal to 1 millionth of a meter or .000039th (39 millionth) of an inch. Another name for micron is micrometer.

MOULD SPORES

Moulds produce tiny spores to reproduce, just as plants produce seeds. Mould spores waft through the indoor and outdoor air continually. When mould spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. There are moulds that can grow on wood, paper, carpet, and foods. When excessive moisture or water accumulates indoors, mould growth will often occur, particularly if the moisture problem remains undiscovered or unaddressed. Moulds can trigger asthma episodes in individuals with an allergic reaction to mould. High performance air filters can easily remove these dangerous pathogens.

NITROGEN DIOXIDE

Combustion appliances such as unflued gas or kerosene space heaters and gas cooking appliances are the major indoor source of NO2. Tobacco smoking and infiltration of outdoor air contaminated by NO2 from sources such as motor vehicles can also contribute to indoor levels.

NO2 causes lung irritation, impaired pulmonary function and has been linked to increased susceptibility to infection. It has been suggested that asthma patients are particularly susceptible to the effect of NO2 on lung function. The NHMRC has not yet introduced an indoor goal for NO2, instead establishing a level of concern of 0.3 ppm. The NHMRC 1-hour ambient goal is 0.16 ppm. The WHO 1-hour goal for both indoor and ambient air is 0.11 ppm.

Indoor hourly average levels of NO2 have been measured to be as high as 1.2 ppm in schools (SPCC 1989), over 0.7 ppm in a hospital (Ferrari et al. 1988) and over 0.8 ppm in dwellings. Figure 1.33 compares indoor and outdoor 1-hour levels of NO2 measured in a number of locations in Australia and New Zealand over the last 10 years. Clearly NO2 levels measured indoors can be significantly higher than those outdoors. Twenty percent of Sydney dwellings using unflued gas space heaters were found to have NO2 levels exceeding the NHMRC level of concern (0.3 ppm), with 58% exceeding the NHMRC ambient goal (0.16 ppm) (McPhail et al. 1988). By comparison, in Adelaide and Perth levels exceeded the level of concern in 4-5% of dwellings (Lyall 1993).

OZONE

Ozone, a lung irritant, is produced indirectly by ion generators and some other electronic air cleaners and directly by ozone generators. While indirect ozone production is of concern, there is even greater concern with the direct, and purposeful introduction of a lung irritant into indoor air. There is no difference, despite some marketers’ claims, between ozone in smog outdoors and ozone produced by these devices. Repeated exposure to ozone pollution may cause permanent damage to the lungs. Even when ozone is present in low levels, inhaling it triggers a variety of health problems including chest pains, coughing, nausea, throat irritation, and congestion. It also can worsen bronchitis, heart disease, emphysema, and asthma, and reduce lung capacity.

Indoor sources of ozone include photocopying machines, laser printers, ionisers and electrostatic precipitators for air cleaning.
Ozone is an irritant and affects the mucous membranes, lung tissue and lung function. At ozone levels above 0.1 ppm sensitive individuals, particularly during exercise, can experience impaired lung function accompanied by respiratory symptoms.

The NHMRC goals for ozone in indoor air are 0.1 ppm for a one hour average and 0.08 ppm for a four hour average, equivalent to the goals for ambient air. While quantitative study has been limited, ozone concentrations in indoor air are generally expected to be lower than ambient levels except in situations where photocopiers are operated in areas with insufficient ventilation.

PARTICLE COUNT

A standard developed for measuring particulate matter in a pre defined area.

PARTICLES

Sources of particles within buildings include combustion appliances (e.g. cookers, heaters), tobacco smoking, deterioration of building materials particularly carpet, dust mite faeces, human skin and the intrusion of outdoor dust. The health problems associated with particles depend on particle size. Smaller particles, less than PM10, are of most concern. Recent health studies indicate an association between mortality and elevated particle levels in ambient air (Morgan et al. in prep a), and elevated PM10 levels have also been linked to impaired lung function and respiratory symptoms.

The NHMRC indoor goal for TSP is an annual mean of 90 µg/m3. The US EPA goals for PM10 are 50 µg/m3 for an annual mean and 150 µg/m3 for 24 hours. Most buildings are affected to some extent but the particulate levels are generally most severe in public buildings where smoking is prevalent. In a Sydney study of 18 clubs and 10 hotels where people were smoking, peak particulate levels reached over 1,300 µg/m3 in clubs and almost 1,000 µg/m3 in hotels (figure 1.34). Cooking can result in high particle levels in kitchens particularly when ventilation is inadequate. In a study of seven kitchens in Sydney, the short-term mean TSP level exceeded 400 µg/m3 with levels over 1,370 µg/m3 measured at one premises (Ferrari et al. 1988). A study of RSP levels in Sydney homes (Ferrari et al. 1988) found an average RSP concentration of 86 µg/m3 in homes with wood fires compared to 28 µg/m3 in homes without. Source: Cummins et al. 1990

PESTICIDES

Pesticides used to control insects have been associated with a variety of health effects ranging from irritation to carcinogenic effects. Indoor levels of pesticides can be elevated as a result of intrusion of termaticides through foundations, use of consumer products or contamination of house dust (Brown 1997). There is no guideline for indoor pesticide concentrations in Australia.
Data on indoor pesticide levels is scarce, but houses treated with termaticides have had levels of 10-50 µg/m3 of termaticide in the first few months after treatment degrading to less than 2 µg/m3 after several years (Meaklin 1992). New termaticides which decay more rapidly and new application techniques may reduce these levels. However the new termaticides have to be reapplied more frequently and the opportunity for high doses persists.

PM10

Particulate Matter Up to 10 Microns in Diameter (PM10)
The number 10 refers to the particle size measured in microns.
PM 10’s are widely considered the most dangerous to human health. Efficient air filtration systems can remove over 99% of particles down to PM 0.3

POLYCYCLIC AROMATIC HYDROCARBONS

Polycyclic aromatic hydrocarbons (PAHs) is the collective name for a number of organic compounds some of which are known carcinogens. Sources of PAHs include combustion appliances such as unflued gas space heaters and stoves, poorly vented slow combustion heaters and open fires, and tobacco smoke. Infiltration of contaminated air from busy streets can be a source of indoor air pollution in some situations. There are no NHMRC or WHO goals for PAHs.
Measurements taken in eight clubs and five hotels in Sydney, where people were smoking, found PAH levels of 19-131 µg/m3 in clubs and 22-75 µg/m3 in hotels (Cummings 1991). These levels are significantly higher than levels measured in ambient air in Sydney.

PRE FILTER

A pre filter is the primary layer of filtration that collects large particles before they reach the HEPA filter or 3M filter. Eliminating these larger particles, dust and hair extends the life of your HEPA filter or 3M filter. Occasional vacuuming of the exterior of the unit will help extend life of the filters. Frequent pre filter changes will also prolong the HEPA filter or 3M filter life.

PRECIPATATOR

There are many simple electronic devices that claim to clean the air in your home by making negative ions and ozone. The claim is accurate–they do make both ozone and negative ions, and they do clean the air in your home. However, that’s not the whole story. First, ozone may have the “fresh” smell that occurs after a thunderstorm (a potent producer of ozone), but ozone is a powerful oxidizing agent and chemical irritant that’s considered an environmental pollutant rather than a charming scent. The manufacturers are taking a nuisance effect and touting it as a “valuable feature.” Second, the negative charges emitted by these electronic devices attach themselves to dust, ash, pollen, and smoke particles and cause those particles to bind themselves to your walls and furniture. The air really does become cleaner, but every surface in your home becomes dirtier as a result.

RADON

Radon, an inert radioactive gas, is emitted from soil and rocks and from rock-based building materials. Underground buildings and dwellings or those constructed with affected material or in areas where emissions from the soil are high can experience elevated levels. Radon gives off alpha particles, a very damaging form of radiation which is a known carcinogen and can cause lung cancer at elevated concentrations. The recommended NHMRC goal is an annual mean of 200 becquerels/m3.

A nationwide survey of 3,413 home conducted by the Australian Radiation Laboratory found an annual average radon concentration of 12 becquerels/m3 (Langroo et al. 1990). Three of the homes exceeded the NHMRC goal and the survey estimated that nationwide 2,000-3,000 homes may exceed the goal (SoEAC 1996).

SICK BUILDING SYNDROME

Sick building syndrome refers to a number of symptoms among occupants which are believed to be building related. The effects associated with sick building syndrome are often non-specific, making assessment difficult, but include allergy sensitivity, irritated eyes, nose or throat, tiredness, headaches and poor concentration. These symptoms are generally thought to occur as a result of indoor emission of VOCs and poor building ventilation.

The type of environments where sick building syndrome is diagnosed include generally poorly maintained air conditioning, new commercial or office buildings fitted with modern materials, or older domestic buildings with damp conditions and mould growth. Temperatures above 21°C, poor lighting, flicker from fluorescent tubes and the absence of windows may also contribute to the problem (SoEAC 1996).

Assessment of building-related illnesses in Australia has been very limited but research so far suggests a dissatisfaction with office air environments (SoEAC 1996).

VOLATILE ORGANIC COMPOUNDS

In indoor environments the term volatile organic compounds (VOCs) refers to a range of organic compounds that are emitted from many materials, equipment and products used in buildings. Outdoors VOCs are also emitted by fuel combustion and industrial and commercial activities (see section 1.4.2). Widespread use of modern materials and furnishing products mean that virtually all buildings are subject to VOCs emissions. Most VOCs at elevated levels can irritate the respiratory tract, eyes and nose. Others, such as benzene, are known or potential carcinogens.

The NHMRC goal for 1-hour average concentrations of total VOCs in indoor air is 500 µg/m3 and for individual VOCs, it is 250 µg/m3. When source materials are used extensively in confined areas such as caravans and mobile homes high levels can result. Limited measurements in Australian dwellings and offices have shown average concentrations of total VOCs of 100-500 µg/m3, with peak concentrations in offices up to 2,700/µg m3 (Brown 1997).