02-02-2013, 12:08 PM
AIR POLLUTION
AIR POLLUTION.pdf (Size: 1.77 MB / Downloads: 382)
HEALTH ,ENVIRONMENTAL and
climate IMPACTS
Air pollution can affect our health in many ways.
Numerous scientific studies have linked air pollution to
a variety of health problems including: (1) aggravation
of respiratory and cardiovascular disease; (2) decreased
lung function; (3) increased frequency and severity of
respiratory symptoms such as difficulty breathing and
coughing; (4) increased susceptibility to respiratory
infections; (5) effects on the nervous system, including
the brain, such as IQ loss and impacts on learning,
memory, and behavior; (6) cancer; and (7) premature
death. Some sensitive individuals appear to be at
greater risk for air pollution-related health effects, for
example, those with pre-existing heart and lung diseases
(e.g., heart failure/ischemic heart disease, asthma,
emphysema, and chronic bronchitis), diabetics, older
adults, and children. In 2008, approximately 127 million
people lived in counties that exceeded national air
quality standards.
SOURCES OF AIR POLLUTION
Air pollution consists of gas and particle contaminants
that are present in the atmosphere. Gaseous pollutants
include SO2 , NOx , ozone, carbon monoxide (CO),
volatile organic compounds (VOCs), certain toxic air
pollutants, and some gaseous forms of metals. Particle
pollution (PM2.5 and PM10) includes a mixture of
compounds. The majority of these compounds can be
grouped into five categories: sulfate, nitrate, elemental
(black) carbon, organic carbon, and crustal material.
Some pollutants are released directly into the
atmosphere. These include gases, such as SO2 , and
some particles, such as crustal material and elemental
carbon. Other pollutants are formed in the air.
Ground-level ozone forms when emissions of NOx
and VOCs react in the presence of sunlight. Similarly,
some particles are formed from other directly emitted
pollutants.