Ozone
Day
On 19
December 1994, the United Nations General Assembly proclaimed 16
September the International Day for the Preservation of the Ozone Layer,
commemorating the date, in 1987, on which the Montreal Protocol on
Substances that Deplete the Ozone Layer was signed.
Ozone is very rare in our atmosphere,
averaging about 3 molecules of ozone for every 10 million air molecules.
In spite of this small amount, ozone plays vital roles in the
atmosphere. Ozone is mainly found in two regions of the Earth's
atmosphere. Most ozone (about 90%) resides in a layer that begins
between 8 to 18 kilometers above the Earth's surface and extends up to
about 50 kilometers, called the stratosphere. The ozone in this region
is commonly known as the ozone layer. The remaining ozone is in the
lower region of the atmosphere, which is commonly called the
troposphere. If we collect all the ozone in the atmosphere, the ozone
layer will be as thick as a one-rupee coin.
Ozone thus plays a key role in the temperature structure of the Earth's
atmosphere. Without the filtering action of the ozone layer, more of the
Sun's UV-B radiation would penetrate the atmosphere and would reach the
Earth's surface. The discovery of the ozone 'hole' in 1985 shocked the
world. It is regarded as one of this century's major environmental
disasters. Many experimental studies of plants and animals and clinical
studies of humans have shown the harmful effects of excessive exposure
to UV-B radiation. It is estimated that, for every 2.5% depletion in
ozone layer results around five-lakh skin cancer patient on earth.
Our country signed in the Montreal Protocol on 17.09.1992. India's per
capita consumption of Ozone Depleting Substances is at present less than
3 grams as against 300 gms permitted under the Protocol. Our country is
taking strict measures to phase out the ozone depleting substances
within the schedule period.
IN THE NEWS - IN
GUJARAT
Science City Organize World Ozone Day Workshop - 16TH SEPTEMBER,
OZONE DAY
To
mark the celebrations for World Ozone Day, Gujarat Science City
(GSC) has organized a day long Workshop with the theme 'Protect
the Ozone Layer : Save Life on Earth' with initiatives for Ozone
Layer protection: Governance and compliances at their best with
exhibition, slide and film show and popular science talk on the
ozone theme. The aim is to spread awareness and sensitize the
students and the general visitors about the ozone layer and its
importance to save life on earth. Participants from over 150
schools are expected to join the workshop on Thursday, 16th
September 2010 - World Ozone Day. A sit and draw and Ozone Quiz
competitions are held at the Science City where children of
class VI to X will participate.
EARTH TALK Q
& A BY EDITOR DOUG MOSS ON OZONE
Dear EarthTalk: I know of
issues associated with the Earth’s ozone layer, but what is
“ground level ozone” and why is that a problem?
Ozone (O3) is a colorless gas formed when three atoms
of oxygen bond together. About 90 percent of the Earth’s ozone
forms naturally in the stratosphere, dozens of miles above
ground. It forms the protective layer that shields us from
overexposure to the sun’s radiation, and is therefore considered
“good” ozone.
The rest of the ozone found on Earth occurs at ground level, and
forms when nitrous oxides and various “volatile organic
compounds’ (VOCs)—originating with car exhaust, industrial
emissions, chemicals and gasoline vapors, as well as some
natural sources—bond together in the presence of sunlight.
Ground level ozone, or “bad” ozone, is a key component of smog,
which wreaks havoc on human health and the environment,
especially in urban areas. The U.S. Environmental Protection
Agency (EPA) reports that exposure to even relatively low
concentrations of ground-level ozone for extended periods
(several hours) can significantly reduce lung function and cause
respiratory inflammation in normal, healthy people. Symptoms can
include chest pain, coughing, nausea and congestion. For people
with asthma and other respiratory illnesses, exercising in
ozone-rich air can be deadly. Repeated exposure to high levels
of ozone for several months or more can produce permanent
structural damage in the lungs.
Beyond its effects on our health, the EPA estimates that
pollution from ground-level ozone is responsible for nearly $2
billion in agricultural crop yield losses in the U.S. alone each
year. The pervasive gas has also been shown to damage forests in
California and the eastern U.S. and to contribute to global
warming.
Under the mandate of the Clean Air Act, the EPA is charged with
monitoring and limiting the amount of ground-level ozone in
urban areas, and issuing warnings when smog levels are above its
standard of 0.12 parts per million. But new studies indicate
that ground-level ozone causes adverse health effects at even
lower concentrations. And, according to the EPA,
even rural areas suffer
increased ozone levels, because wind carries ozone and the
pollutants that form it hundreds of miles away from their
original sources. As a
result, the EPA is reviewing whether revisions to ozone
standards and policies are warranted.
High concentrations of ground-level ozone are not as common in
Canada, but three urban regions—British Columbia’s Lower Fraser
Valley, the Windsor-Québec City Corridor and the Southern
Atlantic Region that includes New Brunswick and Nova Scotia—do
suffer several “bad air days” each year. The Canadian
government, through its own Clean Air Act, has even stricter
standards for exposure to ground-level ozone than in the U.S.,
though enforcement is not as big a priority given the smaller
scope of the problem there.
To help
minimize ground-level ozone, avoid car trips and the use of
power lawn equipment during especially hot or windless days.
Paints and solvents, most which off-gas VOCs that create ozone
and form smog, are also best to steer clear of with hot summer
temperatures coming on strong. Those concerned about their
respiratory health should follow local weather sources, most
which post smog alerts.
CONTACTS: U.S. EPA
Ground-Level Ozone Information,
www.epa.gov/air/ozonepollution;
Canada’s Clean Air Act,
www.ec.gc.ca/cleanair-airpur/Home-WS8C3F7D55-1_En.htm.
- ilaxi patel
