As the intense heat wave conditions continue unabated, Delhi has witnessed significant ozone build-up this summer. The Centre for Science and Environment (CSE) study based on the real-time air quality data available from the key monitoring locations of the Delhi Pollution Control Committee for the period January to early June 2014 shows rapid build-up of ozone, exceeding the standards proposed by the Union ministry of environment and forests.

CSE experts say the ozone build-up is the result of a deadly combination of high pollution levels and an unusually hot summer. Ozone is known to be extremely hazardous for human health.

According to Anumita Roychowdhury, executive director, research and advocacy and head of CSE’s air pollution programme: “Ozone is the new generation public health threat and a difficult challenge. It must be checked at the early stages with stringent controls on nitrogen oxide and toxic and volatile gases, the major ingredients of ozone recipe.”

The CSE has analysed ozone data from the automatic monitoring stations of the DPCC located in R.K. Puram, Civil Lines, Mandir Marg and Punjabi Bagh all residential areas as well as the IGI Airport. “Delhi needs to act immediately to protect public health,” says Roychowd-hury. “Explosive increase in vehicle numbers, especially diesel vehicles that spew much higher levels of nitrogen oxide and volatile organic compounds, can only worsen the deadly recipe needed for formation of ozone in the city with hot and extreme climate.”

Ozone is an extremely harmful gas, particularly for those involved in outdoor activities. Just a few hours of exposure to it can trigger serious health problems, especially among those who are already suffering from respiratory and asthmatic problems. Ozone worsens symptoms of asthma, leads to lung function impairment and damages lung tissues. Chest pain, coughing, nausea, headac-hes and chest congestion are common symptoms.

It can even worsen heart disease, bronchitis and emphysema. It increases emergency hospital visits and admissions related to respiratory diseases.