With densely-populated areas in the city, especially Punjabi Bagh and R.K. Puram, showing high levels of ozone, environmentalists and doctors have expressed their concern over their adverse effect on children, dengue patients, and those with compromised respiratory function.
“In the dengue season, stressed respiratory function with high levels of ozone can work as a fatal combination. This season has seen a large number of deaths in children. Also those with underlying medical condition are at risk. Stressed respiratory system is definitely a concern,” said Dr. Anil Bansal of the Delhi Medical Association.
Ozone exposure unlike other polluting gases is harmful even for a short period of time. “Ozone is the only pollutant that has a one-hour notified average safe limit of 180 micrograms per cubic metre. Along with carbon monoxide, it has an eight-hour average safe limit of 100 micrograms per cubic metre. All other pollutants have 24-hour averages. So even inhaling ozone for one hour can be harmful for asthmatics,” said Dr. T. K. Joshi, director of the Centre for Occupational and Environmental Health at Maulana Azad Medical College.
Environmental scientists say ozone, which is a critical pollutant, has emerged as a concern in Delhi in the last few years. The prevailing high temperatures have contributed to a spike in ozone levels in some parts of the city in the last 24 hours.
Ozone levels vary greatly between areasand areas like Anand Vihar, Civil Lines are at a disadvantage, said Anumita Roychowdhury, executive director, Centre for Science and Environment.
Ozone reduces lung function by inflaming and scarring the lining of the lungs. It can also cause chest pain, cough, and exacerbate existing respiratory diseases like asthma and bronchitis.
“We have been monitoring ozone levels since March and the levels were high during summer. Ozone is formed due to a photochemical reaction between gaseous pollutants like nitrogen dioxide and hydrocarbon gases. So heat and sunlight is a factor, which triggers this reaction,’’ she said. The Centre for Science and Environment is now demanding that alerts be issued to the general public about the spike. “The government should reduce the number of vehicles, especially diesel ones. Our study shows that frequency of days violating ozone standards has increased with the onset of summer,” said Ms. Roychowdhury.
