Indoor air
quality
Relatively little attention is
given to the quality of the air inside our own homes when compared
with the public concern about the health effects of outdoor air
pollutants.
In most buildings the level of indoor air
pollution will be low, but as we spend a large part of our lives
indoors, keeping the indoor air that we breathe free from potential
asthma triggers is important. There are various situations that can
lead to reduced indoor air quality and lead to increasing levels of
adverse health effects.
Fungal Growth:
The growth of fungi or moulds is dependent upon the humidity of
the indoor environment. Mould growth in homes typically occurs
during the winter, when there is often less ventilation, more
moisture generation and cooler surfaces, thus a greater potential
for condensation.
House Dust Mites: Levels of dust mite infestations
depend on the temperature and humidity of their surroundings or
habitat (usually: carpets, cushions, mattress etc). Mites feed on
human skin scales. Infestations can be reduced by more intensive
cleaning regimes and improved ventilation.
Combustion Products:
As well as a fire other sources of combustion products to indoor
air quality are water heating, cooling and space heaters
(especially un-vented gas heaters and paraffin heaters). The
products of combustion are:
-
Carbon Monoxide - A highly toxic gas, which can
build up to dangerous levels when combustion appliances are not
installed and maintained correctly or have insufficient
ventilation. There is a wide range of regulations governing
installation and operation combustion appliances due to the concern
over carbon monoxide poisoning.
-
Oxides of Nitrogen - The key factor affecting
indoor levels and personal exposure to oxides of nitrogen in the UK
is probably the use of gas cookers. Exposure indoor at home was
estimated to represent over 70% of total exposure to Nitrogen
dioxide in the UK.
Environmental Tobacco Smoke:
Tobacco smoke contains over 3,800 different chemical constituents,
both gases and particulates. The lung cancer risk, among
non-smokers passively exposed to tobacco smoke, is estimated to be
24% greater than the risk to non-smokers not exposed at home.
Tobacco smoke is also strongly linked to cardiovascular disease and
respiratory illness both among adults and children.
Volatile Organic Compounds:
The sources in indoor air quality are, cleaning agents, paints,
glues, solvents, cosmetics, building materials and most
manufactured consumer products. Levels of volatile organic
compounds are influenced by: temperature, ventilation, relative
humidity, ventilation rates and age of materials. Generally levels
of volatile organic compounds are highest after manufacture,
reducing within a few months. Health effects include short-term
irritation of the eyes, nose, skin, respiratory tract and annoying
odours. Acute neurotic consequences (e.g. headaches) can occur at
higher concentrations.
Hygrothermal Conditions:
Cold environmental conditions have been associated with increased
deaths from heart attacks, strokes and respiratory illnesses. A
proportion of the excess winter deaths, particularly those due to
respiratory disease, can be attributed to cold indoor conditions.
Controlling Indoor Air Quality:
It is normal for there to be a wide range of gases,
vapours and particles in the indoor air. Control should aim to
reduce levels of pollutants to ensure that adverse health effects
are not experienced. Control measures should be appropriate to the
people in the home, aiming for reductions of allergens where
inhabitants have known alergic reactions. Generally good measures
include ensuring ventilation is sufficient for the size and use of
each room and reducing relative humidity by controlling moisture
sources where possible.
For more information please visit the
air quality pages on the Greater London Authority
website.