The Times of India 21.12.2009
Pollution increases ground-level ozone in city
PUNE: Industrial and vehicular pollution has led to an increase in the tropospheric (ground-level) ozone in Pune's environment at the rate of 1 to 2% per year. And, for the last five years, on some days, it has been crossing permissible limits at noon.
Gufran Beig, programme director and scientist at the Indian Institute of Tropical Meteorology
Gufran Beig, programme director and scientist at the Indian Institute of Tropical Meteorology
(IITM), Pune, told TOI that measurements taken at IITM have shown that ozone concentration has crossed 90 ppb (1 ppb = one ozone molecule per billion of air molecules) over Pune, whereas the WHO limit of ozone in the environment is 80 ppb hourly average. For 40 to 50 days a year in Pune, particularly in the afternoon, this threshold is crossed.
"The concern lies in the fact that ozone is a pollutant and a greenhouse gas. Being toxic it makes it directly related to health effects and causes damage to lung tissue and plants," said Beig.
In addition, Beig warns that this increasing tropospheric ozone (the level between zero to 15 km above the earth's surface) at the rate of 1-2 % per year means that after 36 years, the ozone level will double over Pune.
Ozone shows a maximum concentration around noon and minimum concentration at sunrise. In summer, it is maximum while in the monsoon it is minimum. Ozone concentration increases during a clear sky day and is less so on cloudy and rainy days. Ozone formation processes take place in the presence of sunlight only and around noon ozone formation reaches its peak, he said.
At present, Pune usually experiences ozone concentration of 20 to 80 ppb depending upon the time and season. During the late 19th century it was approximately 10 ppb.
Beig said that this increase in ozone is due to the high level of pollution in Pune. It is directly related to pollution from industries, vehicles, bio-fuel and thermal power emission. It is mainly contributed by industries and vehicles.
The pollutants (from different sources) responsible for ozone formation are oxides of nitrogen, carbon monoxide and volatile organic compounds through chemical reaction.
Explains Beig, "Stratospheric ozone (ozone at the altitude about 25 km from the earth), which acts as protective shield to protect the earth's surface from the sun's harmful ultraviolet (UV) radiation, is decreasing. On the other hand the ozone in the air we breathe, which is harmful, is increasing."
Meanwhile, satellite observational data has shown that during the last 25 years, there has been a 7-8%, per decade, increase in the tropospheric ozone level over India. "So there has been about 20% increase during this 25 years. The maximum trend was seen in China, followed by Thailand, Malaysia and India (in Asian countries)," said Beig.
All over the world, mega-cities are facing the ozone problem in the environment, he said. The Indian region has a high ozone forming potential as this region is getting moderately polluted. It will become more serious if proper steps are not taken, he said.
IMPACT : Ozone is a greenhouse gas, therefore it helps to warm the earth's surface. Its global warming potential is 2000 times more than that of carbon dioxide. It indicates that enhancement of ozone can have large climatic consequences in future.
The recent international CHINAMAP research project (1999) shows that wheat production decreases by 10% or more if ozone concentration is more than 60 ppb in the ambient environment. It indicates that in the near future, it will be difficult to meet the food demands of growing populations like in China and India.
It can produce acute foliar injuries, reduced crops yield and bio-mass production. Ozone disturbs the photosynthesis process, resulting in reduction in crop growth and ultimately reduced crop yield.
HEALTH ASPECT : Ozone is a highly oxidizing agent. It reacts with almost all compounds and living species. Small amounts of ozone, about 40 ppb at ground level, can cause chest pain, coughing, nausea, throat irritation and congestion in healthy people. It may also worsen bronchitis, heart disease, emphysema and asthma.
WAY AHEAD : According to scientists, it's time to take steps. There is a need to come up with improved technology in transport, converting non-conventional sources of energy and replacement of domestic cooking fuel.
Indian region is nitrogen oxides-limited', hence it is easier to control ozone in the environment by taking efficient suitable precautionary measures to control the transport sector by reducing nitrogen oxides, say scientists.
IN OTHER COUNTRIES:
* In Los Angeles the windows of schools are closed due to the high ozone concentration during noon as the developing lungs of children are more susceptible.
* Ozone warning is issued in Japan if its concentration exceeds 120 ppb.
* Mexico city is a unique example of a topographical influence where ozone concentration reaches up to 500 ppb.
"The concern lies in the fact that ozone is a pollutant and a greenhouse gas. Being toxic it makes it directly related to health effects and causes damage to lung tissue and plants," said Beig.
In addition, Beig warns that this increasing tropospheric ozone (the level between zero to 15 km above the earth's surface) at the rate of 1-2 % per year means that after 36 years, the ozone level will double over Pune.
Ozone shows a maximum concentration around noon and minimum concentration at sunrise. In summer, it is maximum while in the monsoon it is minimum. Ozone concentration increases during a clear sky day and is less so on cloudy and rainy days. Ozone formation processes take place in the presence of sunlight only and around noon ozone formation reaches its peak, he said.
At present, Pune usually experiences ozone concentration of 20 to 80 ppb depending upon the time and season. During the late 19th century it was approximately 10 ppb.
Beig said that this increase in ozone is due to the high level of pollution in Pune. It is directly related to pollution from industries, vehicles, bio-fuel and thermal power emission. It is mainly contributed by industries and vehicles.
The pollutants (from different sources) responsible for ozone formation are oxides of nitrogen, carbon monoxide and volatile organic compounds through chemical reaction.
Explains Beig, "Stratospheric ozone (ozone at the altitude about 25 km from the earth), which acts as protective shield to protect the earth's surface from the sun's harmful ultraviolet (UV) radiation, is decreasing. On the other hand the ozone in the air we breathe, which is harmful, is increasing."
Meanwhile, satellite observational data has shown that during the last 25 years, there has been a 7-8%, per decade, increase in the tropospheric ozone level over India. "So there has been about 20% increase during this 25 years. The maximum trend was seen in China, followed by Thailand, Malaysia and India (in Asian countries)," said Beig.
All over the world, mega-cities are facing the ozone problem in the environment, he said. The Indian region has a high ozone forming potential as this region is getting moderately polluted. It will become more serious if proper steps are not taken, he said.
IMPACT : Ozone is a greenhouse gas, therefore it helps to warm the earth's surface. Its global warming potential is 2000 times more than that of carbon dioxide. It indicates that enhancement of ozone can have large climatic consequences in future.
The recent international CHINAMAP research project (1999) shows that wheat production decreases by 10% or more if ozone concentration is more than 60 ppb in the ambient environment. It indicates that in the near future, it will be difficult to meet the food demands of growing populations like in China and India.
It can produce acute foliar injuries, reduced crops yield and bio-mass production. Ozone disturbs the photosynthesis process, resulting in reduction in crop growth and ultimately reduced crop yield.
HEALTH ASPECT : Ozone is a highly oxidizing agent. It reacts with almost all compounds and living species. Small amounts of ozone, about 40 ppb at ground level, can cause chest pain, coughing, nausea, throat irritation and congestion in healthy people. It may also worsen bronchitis, heart disease, emphysema and asthma.
WAY AHEAD : According to scientists, it's time to take steps. There is a need to come up with improved technology in transport, converting non-conventional sources of energy and replacement of domestic cooking fuel.
Indian region is nitrogen oxides-limited', hence it is easier to control ozone in the environment by taking efficient suitable precautionary measures to control the transport sector by reducing nitrogen oxides, say scientists.
IN OTHER COUNTRIES:
* In Los Angeles the windows of schools are closed due to the high ozone concentration during noon as the developing lungs of children are more susceptible.
* Ozone warning is issued in Japan if its concentration exceeds 120 ppb.
* Mexico city is a unique example of a topographical influence where ozone concentration reaches up to 500 ppb.
