Ground level ozone rises alarmingly in Delhi

New Delhi June 15 (UNI) Delhiites have to take extra care of their health this summer as uncommonly high level of ground ozone have been recorded, according to a Centre for Science and Environment study based on the data released by the Central Pollution Control Board.

Ozone is very harmful as even short term exposure can trigger serious health problems. It worsens the symptoms of asthma, leads to lung function impairment and damages lung tissues. Chest pain, coughing, nausea, headaches and chest congestion are common symptoms.

It can even worsen heart disease, bronchitis, and emphysema.

The increase in the ozone level is the result of the deadly combination of high pollution levels and the soaring mercury during this unusually hot summer.

Ozone is not emitted directly from any source. But other pollutants, primarily nitrogen oxides (NOx) and hydrocarbons that are spewed by the growing number of vehicles and other sources in the city react in the atmosphere under the influence of sunlight and high temperature to form ozone.

High dose of NOx, volatile organic compounds, heat and sunlight are its deadly recipe. When ambient temperatures and sunlight remain high for several days as it has happened this summer and the air is relatively stagnant, ozone builds up fast in the air. The CSE said it has assessed ozone data that is generated by the Central Pollution Control Board in its automatic monitoring stations in Sirifort in South Delhi, and Delhi College of Engineering in Bawana at the outskirts of city.

The CSE analysis shows the following: More frequent violation of ozone standards as the temperature rises: While ozone levels in Siri Fort did not exceed the WHO guidelines of 100 microgramme per cum (for daily maximum eight hourly average) for a single day during the winter month of January, the trend changed in the subsequent months.

The number of days violating the WHO guidelines began to increase from February onwards when the climate warmed up --- around 11.5 per cent of days in February, and 35.7 per cent in April. This peaked in May when 43.3 per cent of days reported violation of the WHO guidelines.

The levels remained particularly elevated from May 20 to June 10, 2007. This clearly coincides with the trend in the ambient temperature that increased to uncommonly high levels this summer - touching the range of 38 to 47 degree Celsius.

The CSE urged the government to put in place control strategies for ozone forming gases, especially NOx which is an important catalyst for ozone formation.

It said the Government should introduce daily health alert system to inform the sensitive population (children, elderly, and those suffering from respiratory and cardiac problems) about the high daily levels and enforce emergency pollution control measures such as restricting traffic, allowing only clean fuel and vehicles and public transport in affected areas till the time the high levels dissipate.

UNI