fWHAT
IS OZONE?
Ozone is a thin layer in
the upper atmosphere, which protects life on Earth from
ultraviolet rays, a cause of skin cancer. At lower atmospheric
levels it is an air pollutant. Ground-level ozone can cause
asthma attacks, stunted growth in plants, and corrosion of
certain materials. It is produced by the action of sunlight on
air pollutants, including car exhaust fumes. Conservationists
are now worried over the ozone hole, a continent-size hole in
the ozone layer that has formed over Antarctica. It is believed
that the ozone layer is depleting at a rate of about 5% every
ten years over Northern Europe, with depletion extending south
to the Mediterranean and southern USA. The best known ozone
depeleters are chlorofluorocarbons (CFCs), halons (used in some
fire extinguishers), methyle chloroform and carbon
tetrachloride, and the pesticide methyl bromide.
fWHAT
IS MEANT BY THE TERM, 'JET LAG'?
Air travellers get
exhausted when they cross several time zones in a comparatively
short time as when they fly from India to USA. This phenomenon
is the result of disturbances in the body�s habitual rhythms of
�internal clock� that the body to adapt to a strange new 24-hour
time-scale. This phenomenon is known as jet lag. Time zones are
imaginary lines running from north to south of the map. These
help standardize time throughout the world since it is only
possible to cross them by travelling from east to west or west
to east. Jet lag is thus felt only when long distances are
covered along the east-west axis.
Jet lag involves a feeling of fatigue, hunger at odd intervals
and irregular bowel and bladder movements. One can tackle jet
lag only by relaxing at the end of the journey.
