This summer, the safe standard was violated on 64% of days during April and May as opposed to 50% of days in t... Read More

NEW DELHI: The summer sky may not look smoggy but the air continues to be extremely polluted. An analysis by the Centre for Science and Environment ( CSE ) in the run up to the World Environment Day shows there was significant ozone (03) build up this summer — April and May.

In fact the number of days in April and May, 2017 violating the eight-hour O3 standard is higher this year compared to the previous year.

This summer, the safe standard was violated on 64% of days during April and May as opposed to 50% of days in the same period last year. This year, 8% of the days were in ‘very poor’ category – up to 4.2 times the safe standard, as opposed to 4% during the time in 2016. However, 2016 had a higher share of “poor” category days.

In a statement released on Saturday, CSE has red-flagged this trend because O3 is a highly hazardous gas. Only a few hours of exposure to high levels of O3 can trigger severe asthma attacks and other health problems. It is particularly harmful for outdoor activities. It can have immediate health impact especially among those who are already suffering from respiratory and asthmatic problems even for short duration exposure, CSE researchers said.

Quoting a study by the University of Southern California reported in Lancet, which found that in high-ozone areas the relative risk of developing asthma in children playing three or more sports was more compared to children playing no sports, researchers said ozone worsens 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.

Researchers recommended Delhi and NCR implement a long term action plan that addresses each source of pollution as directed by the Supreme Court recently. They also suggested timely implementation of BS VI standards, discouraging diesel vehicles and scaling up public transport rapidly.

O3 is created due to chemical reactions between oxides of nitrogen (NOX), volatile organic compounds (VOC) and carbon monoxide (CO) in the presence of sunlight and heat.

Sources of NOX and VOCs are usually industrial facilities, motor vehicle exhausts, power plants and others. CSE also analysed how with the increase in temperature in Delhi, O3 levels peaked.

“Due to higher temperature and solar radiation, O3 concentration has also increased. For example, in April 2017, as the temperature increased from 27 degrees Celsius on April 9 to 32 degrees on April 14, the daytime ozone levels increased by 134% — rising from 90 to 211 microgramme per cubic metre. In May when the temperature rose from 32 degrees on May 3 to 36 degrees on May 8, the daytime ozone concentration increased by 130%, spiking from 100 to 230 microgramme per cubic metre,” the analysis said.

An area wise assessment revealed O3 breached the safe standard in 83% of days in April and 100% of days in May at RK Puram. Punjabi Bagh recorded the highest eight-hour average concentration at 416 micrograms per cubic metres. O3 levels violated the safe standard on 78% of days in April at Punjabi Bagh but data for May was unavailable. At Anand Vihar , which is a transport hub, O3 exc eeded the standard on 17% of days in April and 68% of days in May.

While O3 monitoring in other Indian cities is sparse, O3 is included in the daily smog and health alert programmes in countries such as Mexico, the US, China among others.



In Video: Ozone turned Delhi into gas chamber