When it rains in Pune and Nagpur, the raindrops may not taste unusual. But weathermen who recently studied the composition of rainwater from 10 cities are worried that it’s raining ‘acid rain’ caused by vehicular, industrial pollution and frenetic urbanisation.
"In Pune and Nagpur, the amount of acid in rainwater has gone up five times since 1995," said VK Soni, a senior meteorologist with the India Meteorological Department (IMD) who conducted the study with colleague Jayant Sarkar, former director of the IMD’s air pollution unit. The researchers also collaborated with the World Meteorological Organisation.
<b1>Samples of rainwater from this year’s first showers and last year's monsoon from Pune, Nagpur, Vishakhapatnam, Srinagar, Allahabad, Jodhpur, Kodaikanal, Minicoy (Lakshadweep) Mohanbari and Port Blair were tested at the IMD, Pune. The results indicated high amounts of sulphur dioxide and nitrogen oxide — major contents of acid rain — emitted into the atmosphere from vehicles, coal-fired power plants and industries.
The US Environmental Protection Agency (EPA) website says pollutants in acid rain interact in the atmosphere to form fine sulphate and nitrate particles that can be ‘transported long distances by winds and inhaled deep into people’s lungs. Fine particles can also penetrate indoors.’
Some medical practitioners say acid rain is linked to the neuro-degenerative Alzhei-mer’s Disease. "Drinking acidic rainwater directly or consuming vegetables grown on water containing acidic or metallic elements can cause Alzheimer’s," maintained Nagpur-based neurologist Rajeev Deshpande.
Acidic elements in rain are measured on a scale called pH that ranges from 0 to 14. "When there is a decline of 1 pH, it means acidity has gone up by 10 times," said Soni. "In Nagpur, acidic elements in rainwater were 4.7 pH during 2005-06 as against 5.6 in 1995."
At the National Environmental and Engineering Research Institute, Director Sukumar Devotta also blamed acid rain on pollution. "Its sulphur content can damage plants and aquatic life too," he said. Samples of rain from this year are now being collected.