5. GLOBAL ENVIRONMENTAL PROBLEMS
95
Outbreaks of legionellosis have occurred in 1981, 1985, 1988,
1992 in the USA as well as other countries, and, having regard to
the high fatality rate from this disease,
it has been studied quite
extensively. Legionellosis is a lung disease caused by environ-
mental pollution (it does not spread from person to person) with the
bacteria. These bacteria thrive in water, particularly in closed water
circulation systems, ponds, also in air conditioning systems, and they
can be inhaled in the form of aerosols when water is disseminated,
for example, by showers, garden sprinklers, humidifiers and other
equipment. As aerosols bacteria can be transmitted to relatively
long distances.
To prevent legionellosis, it is important to set up and
operate water circulation systems properly. Practically, it means
preventing the reproduction and growth possibilities for bacteria.
Allergic alveolitis can also be caused by micro-organisms in the
air. Alveolitis in its acute form begins six to eight hours after exposure,
and it has the symptoms of an acute respiratory illness, such as fever,
shortness of breath, cough and muscle pain. The sickness may last just
a few days if exposure to the provoking antigen ceases. The chronic
form of the disease is more common in the presence of a constant low-
level
pollution source, for example, domestic animals. This disease
is caused by the fungi, which, for that matter, also cause an allergic
reaction to hay, especially if it is mouldy. The same micro-organisms
can also thrive in air-conditioning and ventilation systems.
The
presence of fungi, bacteria and other micro-organisms in the
indoor air can also cause such diseases as asthma, allergic rhinitis
and the sick building syndrome. The latter has a number of different
symptoms that people may experience while they are living or working
at particular premises and that cease when they leave these premises.
Typical symptoms of this syndrome are irritated and watering eyes,
running nose, headache and sometimes asthma. Air conditioning and
humidification systems can also cause infectious diseases.
Air pollution with asbestos typically occurs only in the human
working and living environ ment. Asbestos is a generic term for
fibrous silicate minerals. The environ ment can be contaminated
by using asbestos cement, asbestos fabrics and asbestos as a heat
insulation material. The hazardous effects of exposure to asbestos
are caused by its mechanical action on the living tissue with which
it comes into contact. In the case of inhaling the air contaminated
with asbestos, a relatively large part of its fine fibres is lodged in the
lungs. Prolonged exposure to asbestos dust may cause asbestosis – a
pulmonary fibrosis caused by asbestos inhalation, associated with
pleural calcification and a possibility of developing into lung cancer.
Asbestosis has a very long latency period – 14 to 35 years.
Another pollutant affecting, first of all, indoors and working
environ ment is radioactive radon (Rn). Radon
is a colourless noble
Since people in deve‑
loped countries spend
indoors approximately
70% of their time,
the indoor air quality
should be given special
attention. The living
environment air pollution
with
asbestos has been
widely studied, proving
its adverse effects on the
human health. However,
the artificially produced
fibrous materials (glass
wool, glass fibre, rock
wool), especially when
they have deteriorated,
may cause similar pollu‑
tion.
Air contamination
in living rooms with the
chemicals typical of out‑
door air pollution – such
as sulphur oxides, heavy
metals, aerosols – also is a
matter of great concern.
96
ENVIRONMENT, POLLUTION, DEVELOPMENT: THE CASE OF UZBEKISTAN
gas, denser than air, formed naturally as an intermediary product in
the decay process of such radioactive elements as uranium (
238
U) or
thorium (
232
Th). Condensed radon has a blue glow. As gas radon is
an inert substance, which is not retained in the human body.
Radon
is hazardous due to the action of atoms separated in its breakdown
process while the gas is in the lungs. Radon decay products are
reactive metals that form oxides and other compounds that are
deposited in the human body. Since these compounds are unstable
and disintegrate further, in this way the human body becomes
exposed to internal ionising radiation. In most cases, the effect of
this radiation is the development of malignant tumours (primarily
lung cancer). Swedish scientists estimate that in Sweden up to 25%
of death occurrences from lung cancer are caused by radon. Indoor
radon contamination is a typical human living environ ment pollution
problem, because high concentrations of radon can occur only in
confined spaces with limited air circulation. Up to 80% of radon
emission comes from soil and the rock weathering process. Since
radon
as gas is very penetrating, it enters into the human living
environ ment through cracks and openings in building foundations.
Drinking water can also be a major source of radon.
In conclusion, considering the substantial effect of indoor air
quality on the human health, the range of issues associated with air
pollution in human living environ ment deserves special attention.
Do'stlaringiz bilan baham: 
