There are several days this summer when ozone has emerged as the dominant pollutant of the day along with particulate matter in daily Air Quality Index
Growing gaseous pollution and increased heat wave and rising summer temperature will worsen this trend.
New Delhi, June 7, 2018: Delhi and the National Capital Region has witnessed substantial ozone build-up this summer, adding to the public health risk, shows a latest analysis done by Centre for Science and Environment (CSE). CSE has analysed the real time air quality data available from close to 31 monitoring locations and reported by the Central Pollution Control Board (CPCB) for the summer months – tracking from February to May 2018.
This shows progressive increase in ozone pollution with the onset of summer. Several densely populated areas have shown high frequency of days violating the ozone standards. With high pollution and temperature levels and growing heat stress, formation of ozone has accelerated and is frequently exceeding the standards.
According to Anumita Roychowdhury, executive director, research and advocacy and head of CSE’s air pollution programme, “While we know that the problem of ozone escalates during summer, the surprise this year is the number of days when the daily Air Quality Index has shown ozone also as a dominant pollutant along with the particulate matter. These are the early signs of a grave trend. Even before the health risk from particulate matter could be addressed, ozone has raised its ugly head in Delhi and NCR. The comprehensive action plan will require stringent and time-bound action to avert public health crisis.”
Heat waves and stronger sunshine increase the frequency of days during summer when ozone begins to cross the standards posing public health risk. Ground level ozone is not directly emitted by any source. This is formed when oxides of nitrogen (NOX) and a range of volatile gases primarily from vehicles and other sources are exposed to each other in sunlight.
Warm and stagnant air increases the formation of ozone. This is also the reason why we see high variability across the region depending on the local and meteorological conditions. Ozone is extremely hazardous for human health. All neighbourhoods in Delhi – rich and poor – and even open spaces, are at risk.
What has CSE found?
CSE has analysed ozone data from February to May 2018, to understand the ozone build-up this summer. It has considered ozone data from 31 automatic monitoring stations of Delhi Pollution Control Committee, Central Pollution Control Board and India Meteorological Department. Continuous data is available for 29 stations for this period. Data from the other two stations is sporadic. This has exposed worrying trends in the city.
Ozone spikes as summer progresses: Consistent with the earlier trends, as summer progressed from February to May this year, the number and frequency of days exceeding the ozone standard has also increased. While frequency and number of days with levels exceeding the standards vary widely across monitoring stations and locations, at least 90 per cent of the stations have recorded levels that exceeded the eight-hour ozone standard on some days at least. Most of the days the level of exceedence is at moderate level with only a few days in some locations like R K Puram, Pusa etc hitting the poor or very poor level.
On multiple days, ozone has showed up as the dominant pollutant along with particulate matter in the daily Air Quality Index: Daily Air Quality Index that depicts the leading and most dominant pollutant of the day, and is largely led by particulate matter in Delhi and NCR, showed surprisingly that there were at least 23 days during this period from February to May, when ozone also emerged as the major pollutant along with particulate matter in the daily air quality index. It may be noted that National Air Quality Index classifies daily air quality based on degree of severity. Based on ambient concentrations of a pollutant, sub-index is calculated for each criteria pollutant. The worst sub-index determines the overall AQI for the day. Thus, on 23 days the sub index of ozone has shown it to be a dominant pollutant this summer along with the particulate matter. This can be due to the fact that particulate pollution was comparatively lower due to meteorological conditions in the city. But this also indicates ozone is the next and close threat.
Densely populated areas vulnerable to frequent exceedence of ozone standards: With large number of air quality monitors in the region this year, it has been possible to do micro mapping of ozone levels across the city to understand the vulnerable areas. This shows that there are some locations where more than 50 per cent of the days during the entire period (February to May), ozone levels have exceeded the standards. These vulnerable areas include the residential areas of Patparganj, RK Puram and Nehru Nagar; and industrial areas and low income areas of Najafgarh and Sonia Vihar.
Patparganj: 39% of days in February, 89% in March, 83% April and 74% in May
RK Puram: 21% in February, 53% in March, 65% in April, 58% in May
Nehru Nagar: 8% in February, 45% in March, 69% in April, 90% in May
Najafgarh: 29% in February, 58% in March, 73% in April, 87% in May
Sonia Vihar: 29% in February, 47% in March, 87% in April, 80% in May
In addition to this, the highest eight-hour ozone levels have been recorded in Najafgarh, Patparganj, Punjabi Bagh and Pusa where on certain days the levels have gone up close to two times the standard.
Green areas more vulnerable: It is very starkly evident that green areas on the outskirts of the city like Dr. Karni Singh Shooting Range near Asola sanctuary are most vulnerable. In Dr Karni Singh Shooting Range, ozone levels have exceeded the 8 hour average standards on 54 per cent of days in February, 87 per cent in March, 90 per cent in April, and 90 per cent in May. This is very consistent from what we know from science. Ozone is formed in polluted areas and some of this that escapes with the wind to cleaner environments at the outskirts and build up there as it has no opportunity to further react with other pollutant to dissipate as it happens in the polluted areas in a cyclical process.
Lutyen’s and Central Delhi are also affected: Air quality monitoring in Jawaharlal Nehru Stadium (JLN) near Lodi Road CGO Complex and Major Dhyan Chand National Stadium near Delhi High Court have shown that the number of days with levels exceeding the standards are 47 per cent and 22 per cent of all days during the entire period, respectively. In JLN stadium, only 4 per cent of days in February had exceeded the standards, but it increased to 74 per cent in May. In Major Dhyan Chand station it increased from zero days in February to 61 per cent of days in May. However, Lodhi Road station shows low level of exceedence.
Ozone is becoming an NCR-wide problem – Gurugram in dubious lead: Among the key NCR towns Gurugram has experienced highest number of days with ozone levels exceeding the 8 hour standard during April and May of 2018. On 57 per cent of days during this period, ozone has recorded levels higher than the standards; during May alone, 71 per cent of the days have recorded exceedence. In Faridabad, 34 per cent of days, and in Noida 26 per cent of days, have recorded exceedence. Ghaziabad, however shows much lower number of days that have been impacted – 3 per cent.
Why should we worry about ozone?
Global experience has shown that as the pollution from combustion sources grow that are the emitters of nitrogen oxide and other volatile compounds, ozone formation increases and remains obstinate. India is also falling in that trap and needs early preventive action.
Already the earlier burden of disease study from Health Effect Institute in 2017 had shown that early deaths due to ozone have jumped by 148 per cent in India. Ozone aggravates respiratory problems, especially chronic obstructive pulmonary disease (COPD). According to scientists, formation of ozone is expected to be higher in countries in tropics and sub-tropics and near the equator. To some extent, rising temperature is also aggravating this trend.
India will be well advised to take early and stringent steps to control ozone precursors which are very difficult to control. This means stringent control of gaseous emissions from combustion sources including vehicles. Ozone precursors like nitrogen oxides, carbon monoxides and volatile organic compounds also have serious local public health impacts.
Ozone is an extremely harmful gas: just a few hours of exposure to it can trigger serious health problems. Ozone is particularly harmful for outdoor activities. This can have immediate health impact especially among those who are already suffering from respiratory and asthmatic problems even for short duration exposure. 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. It increases emergency hospital visits and admissions related to respiratory diseases.
A study by the University of Southern California and reported in Lancet, has 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. Outdoor heavy exercise is not recommended as with every breath, and athletes particularly take in 10 to 20 times as much air, and thus pollutants, as sedentary people do.
Scientists inform that ozone is a powerful oxidizer, which means it can damage cells in a process akin to rusting. Children and the elderly are at special risk. There is a strong association between ozone and daily premature death counts. Those with pre-existing diseases and lung diseases are at serious risk. Growing concentrations of nitrogen oxide and volatile organic compounds from combustion sources especially from the explosive increase in diesel vehicles is adding to the deadly recipe of ozone in hot and extreme climate. Also ozone that gets created in the polluted environ of the city can also drift depending on the wind direction towards cleaner environs in rural periphery and begins to accumulate as it has less chances of reacting with other pollutants in cleaner environment. Hence it builds up fast at the outskirts. It is known to damage crop.
Need urgent and preventive action
Delhi and NCR needs much high degree of health protection for all and especially the high risk groups including the elderly, children, outdoor workers and people with asthma and lung disease.
The recently finalized Comprehensive Action Plan must kick off immediately and should be implemented with absolute stringency and disciplined monitoring in a time bound manner. This is needed for targeted reduction of gaseous emissions from vehicles, industry and power plants.
For more details or interviews, please contact Souparno Banerjee of The CSE Media Resource Centre, firstname.lastname@example.org / 9910864339.