Indoor air quality: heading towards ‘sick’ buildings

Specialists are not needed anymore to verify the fact that air pollution has become a major
problem. Much has been written about, many discussions held and many an initiative taken
to address this problem. However, all the attention and energy has largely, if not wholly,
focused on outdoor air pollution.
One of the greatest myths surrounding air pollution is that whatever dangers we face is
when one is outdoors, and are quite safe once we enter the safe confines of our homes and
offices. This sense of security is heightened when the homes and/or office are air-
However, recent findings by the scientists at the Tata Energy Research Institute (TERI) belie
this myth. A three-year long study, which covered several buildings in the city of Delhi, has
revealed that indoor air pollution can be as toxic and as much of a nuisance as the outdoor
air pollution. Says Dr Sumeet Saksena, Fellow, TERI, "Although relatively little is known
about the hazards of many substances found in indoor air, the need to understand this part
of our environment is obvious. On an average, one spends 80%− 90% of the time indoors".
Research indicates several detrimental effects of poor indoor environment on the
productivity of employees in office buildings, including those that are air-conditioned, and
on their general health. Hence, for a large number of people, poor indoor air quality may
pose more of a health problem than the air pollution outdoors. Also, people exposed to
indoor air pollutants over a long period of time may become more vulnerable to outdoor air
pollutants. Such groups include the young, the elderly and the chronically ill, especially
those suffering from respiratory and cardiovascular diseases.
The sources of indoor pollution are different for rural and urban areas. In the former, the
main pollutant sources are from human activities such as cooking, especially when using
bio-mass fuels such as wood and dung, smoking and certain types of building materials. Key
pollutants in urban buildings include nitrogen dioxide, carbon monoxide, radon (from
building materials, water and soil), formaldehyde (from insulation), asbestos, mercury,
man-made mineral fibers, volatile organic compounds, allergens and tobacco smoke – as
well as health damaging organisms like bacteria. Most of these health problems arise in
buildings made from materials that give off these pollutants, especially radon, asbestos
particles, formaldehyde, and volatile organic compounds. Claims R Uma, Research Associate
at TERI, "Given the thrust on energy-efficiency in air-conditioned buildings, the level of
ventilation with the external environment is rather low. These pollutants are often re-
circulated indefinitely in offices and homes and can achieve high concentration levels".
Getting detailed information on indoor air quality assumes importance as it affects human
health to varying degrees depending on the particular pollutant, the level of concentration in
the air and the and the sensitivity of the individual. The large proportion of time that most
people spend inside air-conditioned spaces increases the likelihood that poor indoor quality
may cause adverse reactions such as allergies, eye irritation, headaches, feeling of
confusion and drowsiness as well as more serious long term effects.
Components of indoor air pollution
Carbon dioxide
Carbon dioxide (CO2) is one of the most common gases found on the face of this planet. A
naturally occurring gas that is produced by combustion processes, CO2 is a byproduct of the
natural metabolism of living organisms. CO2 levels can be used as an indicator to evaluate
whether adequate ventilation is taking place in a building. A high concentration of CO2 may
indicate that other contaminants in the building may be concentrating. Problems associated
with high CO2 levels are drowsiness, fatigue, and the sick building syndrome.
Environmental tobacco smoke
Environmental tobacco smoke (ETS) is one of the major sources of indoor air contaminants.
Inhalation of ETS is commonly termed as "second hand smoking" or "passive smoking". The
ubiquitous nature of ETS in indoor environment indicates that some unintentional inhalation
of ETS by non-smokers is inevitable. Environmental tobacco smoke is a dynamic and
complex mixture of more than 4000 chemicals found in both vapour and particle phases.
Many of these chemicals are known toxic or carcinogenic agents. Non-smoker exposure to
ETS-related toxicants would occur in indoor spaces where there is smoking. The US
Environmental Protection Agency (EPA) has classified ETS as a known human carcinogen
and estimates that it is responsible for approximately 3000 lung cancer deaths every year in
the US. Children’s lungs are even more susceptible to harmful effects caused by ETS. There
is also strong evidence of increased middle ear effusion, reduced lung function and reduced
lung growth in children exposed to ETS.
Combustion in stoves, space heaters, furnaces and fireplaces
Apart from ETS, the major combustion pollutants that may be present at harmful levels in
the home or workplace stem chiefly from malfunctioning heating devices, or inappropriate,
inefficient use of such devices. Another source maybe motor vehicle emissions due to, for
example, proximity to a garage or a main road. A variety of particulates acting as additional
irritants or, in some cases, carcinogens may also be released n the course of combustion.
Among possible sources of contaminants: gas ranges that malfunction or are used as heat
sources, improperly ventilated fireplaces, furnaces, wood or coal stoves, gas water heaters
and gas clothes dryers and improperly used kerosene or gas space heaters. The gaseous
pollutants from these combustion sources include some identified as prominent atmospheric
pollutants – carbon monoxide (CO), nitrogen dioxide (NO2) and sulphur dioxide (SO2).
Carbon monoxide causes asphyxiation. An accumulation of this odourless, colourless gas
may result in a varied constellation of symptoms deriving from the compound’s for and
combination with hemoglobin, forming carboxyhemoglobin (COHb) and disrupting oxygen
transport. The elderly, the foetuses, and people with cardiovascular and pulmonary diseases
are particularly sensitive to elevated CO levels. Methylene chloride, found in some common
household products like paint strippers, can be metabolized to form carbon monoxide, which
combines with hemoglobin to form COHb. Studies involving controlled exposure have shown
that CO exposure shortens time to the onset of angina in individuals with ischemic heart
disease and decreases exercise tolerance in those with chronic obstructive pulmonary
disease. Since CO poisoning can mimic influenza, the health care provider should be
suspicious when an entire family exhibits symptoms such as fatigue, headache, dizziness,
nausea and vomiting. Nitrogen dioxide and sulfur dioxide act mainly as irritants, affecting
the mucosa of the eyes, nose, throat and respiratory tract. Continued exposure to high NO2
levels can contribute to the development of acute or chronic bronchitis.
Volatile organic compounds
At room temperature, volatile organic compounds (VOCs) are emitted as gases from certain
solids or liquids. These include formaldehyde, pesticides, solvents, solvents, and cleaning
agents. VOCs are consistently found at higher levels indoors than outdoors. Products used in
home, office, school, and arts/crafts and hobby activities emit a wide array of VOCs. These
products include scents, hair sprays, rug, oven cleaners, dry-cleaning fluids, home
furnishings, office material like copiers, certain printers, correction fluids, graphics and craft
materials etc. Formaldehyde has been classified as a probable human carcinogen. Pesticides
sold for household use are technically classified as semi-volatile organic compounds.
Symptoms like conjunctival irritation, nose and throat irritation, headache, allergic skin
reaction, and nausea may indicate the presence of these VOCs.
Heavy Metals: airborne lead and mercury vapour
Most health professionals are aware of the threat of lead toxicity particularly on children in
the form of cognitive and developmental deficits, which are often cumulative and subtle.
Lead toxicity may alternatively manifest itself as acute illness. Signs and symptoms in
children may include irritability, abdominal pain, emesis, marked ataxia and seizures or loss
of consciousness. Lead poisoning via ingestion has been the most widely publicized,
stressing the roles played by nibbling of flaking paint by toddlers and by the use of lead
containing foodware like glass and soldered metal-ceramic ware by adults. Lead levels in
paint for interior use has been increasingly restricted in countries like US, since the 1950’s
and many paints are now virtually lead-free. However, new paint too has emerged as a
source of worry in which mercury has replaced lead.
Sick building syndrome
The term Sick building syndrome (SBS), first employed in the 1970’s, describes a situation
in which reported symptoms among a population of building occupants can be temporarily
associated with their presence in that building. Generally, a spectrum of specific and non-
specific complaints is involved. Typical complaints include lethargy, headache, dizziness,
nausea, eye irritation, nasal congestion, and inability to concentrate. SBS should be
suspected when a substantial proportion of those spending extended times in a building
report or experience acute on-site discomfort. There has been extensive speculation about
the causes of SBS. Poor design, maintenance, and operation of the structure’s ventilation
system may be at fault. Another theory suggests that very low levels of specific pollutants
may act synergistically to cause health problems. Humidity may also be a factor. While high
relative humidity may contribute to biological pollutant problems, an unusually low level
(below 20 or 30 percent) may heighten the effects of mucosal irritants and may even prove
irritating itself. Other contributing elements may include poor lighting and adverse
ergonomic conditions, temperature extremes, noise and psychological stresses that may
have both individual and interpersonal impact. The prevalence of the problem is still
unknown. A 1984 World Health Organization report suggested that as many as 30 percent
of new and remodeled buildings worldwide might generate excessive complaints related to
indoor air quality. When SBS is suspected, the individual physician or other health care
provider may need to join forces with others to adequately investigate the problem and
develop appropriate solutions.
Results and recommendations
It was keeping these concerns in mind that TERI scientists began conducting research on
indoor air pollution in several buildings in Delhi, the notable ones being situated at ITO and
Nehru Place.
Most of the buildings have their nitrogen dioxide and sulfur dioxide levels to be higher in
outdoors than indoors. Similarly, formaldehyde and lead have been found to be higher
outdoors than indoors. Carbon dioxide levels are far higher indoors than outdoors. This is
due to inadequate ventilation.
Respirable suspended particulate (RSP) and suspended particulate matter (SPM) exceeded
the ASHRAE (American Society of Heating, Refrigeration and Air-conditioning Engineers)
standard respectively. Outdoor concentrations have been observed higher than those found
indoors. The methods applied to detect major indoor pollutants like asbestos, carbon
monoxide and ozone were NIOSH (National Institute for Occupational Safety) for asbestos,
electrochemical for carbon monoxide and colorimetric for ozone. These were normally found
below safe limits.
In most of the buildings that were monitored, the particulate pollution is a major problem
(both SPM and RSP). The CO2 levels are higher than outdoors. The particulate pollution
indoors may be due to infiltration as the particulate levels outdoors are very high. Most of
the air-handling units utilize synthetic filters, which can only remove particles of sizes larger
than 20 micron. The smaller-sized particles thus enter these buildings freely, and since
these are respirable, they are more dangerous.
ASHRAE recommends a minimum fresh airflow of 15 cubic feet per minute per person for
air-conditioned spaces to maintain the quality of indoor air. Given the highly polluted
outdoor air in Indian cities, fresh air intake without proper filtration may increase the
pollution level inside. A solution is to employ high-efficiency particulate air (HEPA) filters
with a fan to provide the required ventilation rate. However, these are expensive and
recurring costs in terms of energy used are high. Even the air-conditioning unit would have
to upgraded as the rate of outside air intake is increased.
Thus, a trade-off has to made between the need for fresh air and need to increase energy
efficiency levels.

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