most of us spend most of our time indoors, indoor air quality is paramount to
our health and comfort. In the last decade, increasing scientific evidence has
show the air within buildings can be more seriously polluted than the outdoor
show that the more people spend time indoor the concentration of contaminants
may build up in an enclosed space, the risks to health may be greater due to
exposure to air pollution indoors than outdoors.
air quality (IAQ) is a result of complex relationship between the contaminant
sources in a building and the ventilation rate which can affects the health and
well-being of occupants. Some of the main factors affecting IAQ in buildings
Emission from indoor contamination source
b) Thermal Acceptability
c) Maintenance of normal concentrations of respiratory gases; and
d) Dilution and removal of contaminants to levels below health or odour
contamination source in a building are the primary determinants of IAQ. They
include building materials, consumer products, cleaners, furnishing, combustion
appliance and processes, biological growth, building occupants, etc. The
physiological reaction to air coupled with the wide range of human
susceptibility to indoor air contaminant, have lead to acute building
sicknesses such as sick building syndrome (SBS), building-related illness (BRI)
and multiple chemical sensitivity.
Indoor Air pollutions and their source
Formaldehyde, is one
of the most important indoor air contaminants, it is highly reactive and
soluble. It is irritable to moist body surfaces. It has been identified as a
“carcinogen” and linked particularly to nasal cancer. Mobile homes have been
found to have higher concentration of formaldehyde because of the extensive use
of particleboards and plywood in construction, tight sealing, and increased use
of recalculated air.
source of indoor air is radon gas, it is a decay product of radium-226, it’s
odourless, colourless radioactive gas and it is a chemical inert. Most people
who get exposed to radon is because or the radioactive elements contained in
the bedrock and soils. Exposure to high concentration of radon has serious health
Soil is the main
source of indoor radon. It enters the building through crawl spaces, hollow
concrete block walls and crack concrete slabs. The main health effect due to
exposure to radon is the increased possibility of cancer of internal organs
such as lung cancer.
into the lungs may cause various health problems. Asbestos, used for insulation
and fireproofing mostly in old buildings is a significant IAQ problem. Asbestos
contaminants occur when the fibres become friable and released into indoor air.
Asbestos is carcinogen and has been linked to stomach and lung cancers.
Fiberglas and Rockwool are also insulation materials that can cause indoor air
We are all exposed to
microorganisms everyday. These include viruses, bacteria, and fungal spores to
pollen grains and dust mites. These sometimes cause sneezing and wheezing and
others may cause severe diseases. Also, a contaminated heating, ventilating and
air-conditioning (HVAC) system can distribute millions of microorganisms.
are of great concern to us, because they can cause diseases. Some
microorganisms can cause allergic reactions, irritation and weaken immunity so
that the body can become susceptible to other diseases. High humidity and
condensation also increase the number of airborne fungal spores and bacterial
Carbon monoxide (CO),
Sulfur dioxide (SO2), Nitrogen Dioxide (NO2) and carbon dioxide (CO2) are among
some of the major byproducts of combustion of indoor air contaminant. CO is an
odourless, tasteless and colorless gas. It combines with haemoglobin in the
blood to form carboxyhemoglobin (COHb) which interferes with the ability of
blood to carry oxygen to the blood tissue. High level exposure of CO may cause dizziness,
headaches, nausea, vomiting, coma, and even death.
SO2 is produced during
the combustion of sulfur-containing material. It is soluble is water and
absorbs easily by the mucous membranes of the respiratory system. Exposure to
SO2 primarily affects the respiratory system.
NO2 is a dark brown
gas, exposure will result in sever irritation to eyes and other membranes of
the body, and damage to the lungs.
CO2 is relatively
nontoxic and considered to be excellent surrogate for odour and indirect measure
of the adequacy of mixing outside and recirculated air.
VOCs are used in the
formulation of almost all materials and products such as construction material,
furnishing, fuels, consumer products and pesticides. Indoor VOC levels are
often much higher than outside concentrations outside. They are lipid soluble
compound and often absorbed through the lungs.
How indoor air pollution affect you
The effect of IAQ can
be categorised as;
● Chronic health
● Acute health effects
It is likely
contaminants in indoor environment can increase the risk of illness and affect
work productivity. Health effects linked with chronic low-level exposure to
common indoor air pollutants still remain unexplored. The effects could be
divided into six categories:
Chronic obstructive pulmonary disease,
Infectious disease and microbial toxins,
Irritation phenomena, and
Health effects from
indoor air pollutants may very from person to person and can be immediate or
years later. Effects may be experienced shortly after a single exposure or
several. Symptoms includes respiratory conditions, watering eyes, Itching eyes,
nose, and throat, Sneezing, conjunctivitis, allergic Reactions, asthma,
Humidifier Fever, Influenza, Infectious diseases, headaches, Breathing
difficulties, Skin irritation, allergic reactions, aggravation of asthma
symptoms, lung cancer, respiratory irritation, bronchitis, pneumonia in
children, emphysema, lung cancer, fatigue and Heart Disease. Some of these
health effects are usually short-term and treatable. The most effective
treatment in most cases is eliminating the source of the exposure.
Other health effects
which includes respiratory conditions, Heart Disease and cancer, can be fatal.
It is important to note that some minor indoor air quality problems can go
unnoticed, however even such low exposure can affect the productivity and
morale of the occupants. In a work environment this may manifest in the form of
lost in concentration and increased absenteeism leading to financial losses.
IAQ issues can have several economic impacts at both individual and
Sick building syndrome (SBS)
building Syndrome (SBS) is often associated with buildings in which a majority
of occupants experience a variety of health and comfort problems for which no
specific cause can be identified. Health related complaints from occupants
often include irritation of eyes, nose, throat and upper respiratory.
Lack of Circulation
Limited fresh Air
Toxic Cleaning chemicals
Natural Gas & CO2
Bacteria in toilet.
Carbon Monoxide (CO)
Oil & Gas Fumes
SBS is mainly based upon the exclusion of other disease and is determined
essentially by perception. The common symptoms associated with SBS include.