The
rapid urbanization of many cities in developing countries with its associated
industrial and transportation system expansion has led to serious levels of air
pollution. Air pollution has serious health risks and poses as a major
environmental health problem, causing death or disease to millions of people
each year. It is estimated that around three million people die of air pollution
annually, which represents 5% of the annual deaths occurring around the world.
Diseases
associated with air pollution are mainly respiratory diseases, asthma, chronic
obstructive pulmonary disease, cardiovascular disease and cancer of the lung.
According to the World Health Organisation (WHO), “Around 30-40% of
cases of asthma and 20-30% of all respiratory diseases may be linked to air
pollution in some populations. Studies in São Paulo, Brazil, have shown
that a 75 µg/mł increase in concentrations of nitrogen dioxide (NO2) was
related to a 30% increase in deaths from respiratory illness in children under
five years of age. In adult non-smokers, chronic exposure to environmental
tobacco smoke increases mortality from lung cancer by between 20% and 30%.”
Persons
most at risk are those suffering from respiratory diseases, extremes of age and
the poor. Air pollutants enter the body either directly through the respiratory
tract and lungs or can be taken up by the blood stream and distributed
throughout the body. Pollutants can also contaminate food and water and become
ingested. It has been shown in various studies that life expectancy can be
reduced significantly in communities with high levels of particulate matter in
the air they breathe.
Indoor
Air Pollution
Not
only are cities affected by dangerous levels of air pollution, but rural areas
may suffer even more due to high levels of indoor air pollution. In fact, indoor
air pollution poses a greater risk in developing countries than ambient air
pollution.
Over
2000 million people around the world use coal and biomass fuels such as wood,
cow dung, charcoal and grass for cooking and heating. The pollutants that result
from the burning of these fuels in inefficient stoves together with poor
ventilation have severe and sometimes fatal consequences. Those most affected
are children. The Global Burden of Disease study conducted by WHO in 1990 showed
that 30% of the estimated number of deaths from all diseases occur before the
age of 15, but for acute respiratory diseases, the figure is twice as high.
Indoor
pollutants are 1000 times more likely to reach people’s lungs than outdoor
pollutants. In India, 80% of households use bio fuels and the estimated child
mortality rate from indoor air pollution is half a million children per year,
mainly from acute respiratory disease. In sub-Saharan Africa there is an
estimated 300,000-500,000 deaths. In Latin America, where one quarter of homes
use bio fuels, an estimated 30,000 people die each year from indoor air
pollution related to acute respiratory tract infections. In Asia there is an
estimated half to one million deaths each year.
Indoor
air pollution is also responsible for a third of all cases of occupational
illnesses. 50 million cases of occupational chronic respiratory disease are
primarily caused by this type of pollution.
The
main health hazards related to indoor air pollution are chronic obstructive lung
disease, lung cancers, adverse pregnancy outcomes in women, and respiratory
problems in children (RAPIDC).
Air
Pollution and Crops
Air
pollution has adverse effects on crops and forests especially in areas in close
proximity to the source of pollution. Negative impacts include:
*
Direct visible damage to the leaf surface which affects crop value.
*
Reduction of crop yield and forest decline. For example, in Pakistan one study
observed a 42% reduction in rice grain yield. In the 1970s and 1980s thousands
of hectares of forest were lost in the ‘Black Triangle’ of Central Europe.
*
Increased sensitivity to stress factors such as drought, frost and pests due to
subtle physiological, chemical or anatomical changes.
The
most damaging pollutants are sulphur dioxide (SO2), nitrogen dioxide (NO2) and
ozone (O3). Climate plays an important role in the uptake and production of
these pollutants. For example, high humidity favours stomatal uptake of
pollutant gases and tropical climates favour the production of ozone which is a
secondary pollutant formed by photochemical reactions involving nitrogen oxides
(NO) and volatile organic compounds (VOCs).
Effects
on Buildings and Cultural Heritage
High concentrations of SO2 and the ever-growing car traffic in several large
cities in developing countries compose an important risk to both buildings and
cultural heritage. Pollutants have several harmful effects including: loss of
mechanical strength, leakage, pipe corrosion, loss of protective coatings and
loss of details in carvings (RAPIDC).
Damage
can occur by direct effect especially to structures close to the source of
pollution. The fact that many developing countries have high relative humidity,
high temperature and a high frequency of precipitation increases the influence
of acidifying pollutants. The acidification of soil and water can also damage
structures indirectly.
Cultural
heritage is at great risk from air pollutants especially SO2. In countries such
as South-Western China where sulphur containing coal is used as the primary
source of energy, corrosion rates are significantly higher than the highest
levels in Europe. Items at risk include sculptures, paintings, textiles, rock
carvings and stained glass. In France it is estimated that 80,000 m2 of medieval
stained glass windows in churches are at risk of corrosion. In Egypt, a 550
pound chunk of limestone fell from the Sphinx in 1988, and while previously
protected by sand, its exposure in the early 20th century and its subsequent
exposure to modern-day pollutants have been causing serious physical
deterioration to it for years.
Types
of Pollutants
Industries
that produce particularly high levels of air pollutants include: chemical,
cement, paper and pulp, iron and steel, non-ferrous metals, glass and ceramics,
leather, refining and processing petroleum, and particularly from coal and oil
burning plants producing electric power.
In
developed countries, traffic is responsible for 30% of the emissions of nitrogen
oxides, 50% of hydrocarbons, 60% of lead and 60% of carbon monoxide in cities.
The percentage rises to as much as 95% for carbon monoxide and up to 70% of
nitrogen oxides in city centers (WHO).
The
most important air pollutant is particulate matter as it affects more people on
a regular basis than any other pollutant. It is made up of coarse particles such
as soil, ash, and engine exhausts. These particles, especially those with
diameters of less than 10 microns deposit on the pulmonary region of the
respiratory tract and cause irritation, and increase the rate of respiratory
tract infections. They also aggravate cases of asthma and bronchitis. Infants
and children are particularly susceptible.
Gaseous
pollutants include nitrogen oxides, sulphur dioxide (SO2), carbon monoxide (CO),
and ozone (O3), which impairs lung function and causes irritation to mucous
membranes, cough and headache.
Others
include ammonia (NH3), volatile organic compounds, chlorinated fluorocarbons
(CFCs), lead and other heavy metals and radon.
Sources:
-
Ashmore,
M.R. and Marshall, F.M, 2002: Corrosion
impacts of air pollution in developing countries. SEI.
-
Ezzati
M, Kammen D.M. 2002: The
health impacts of exposure to indoor air pollution from solid fuels in
developing countries: knowledge, gaps, and data needs. Environ Health
Perspect; 110(11):1057-68.
-
RAPIDC,
2002: Impacts
of Air Pollution on Crops and Forests. SEI.
-
RAPIDC,
2002: Impacts
of Air Pollution on Health. SEI.
-
RAPIDC,
2002: Corrosion
Impacts on Buildings and Materials. SEI.
-
WHO,
1998: Fact
Sheet N° 187, Air Pollution.
-
WHO,
2000: Press
Release, WHO/56, Danger in the Air.
Aisha
El-Awady is an IslamOnline.net staff-writer. She has a
bachelor’s degree in medicine from Cairo University and is currently working
as instructor of Parasitology in the Faculty of Medicine. She may be
contacted at aawady@islam-online.net
