Ozone levels increase in Delhi, pose health risk

This could lead to a public health crisis as ozone is extremely hazardous to human health

By Shambhavi Shukla
Published: Friday 12 April 2019
Photo: iStock

Delhi is witnessing a rise in average ozone levels, which ups the public health risk in the Capital.

Several densely populated areas have shown high frequency of days violating the ozone standards, reveals an analysis of the past 12 days’ data by Centre for Science and Environment, a New Delhi-based think tank.

With high pollution and temperature levels and growing heat stress, formation of ozone has accelerated and is frequently exceeding the standards, shows the analysis. These locations include Ashok Vihar, Bawana, Dwarka Sector-8, Jahangirpuri, Najafgarh, Narela, Nehru Nagar, Rohini, Siri Fort, Sri Aurobindo Marg and Vivek Vihar.

This year, 38 per cent of the 36 locations monitored are exceeding the eight-hour average ozone standard. On some days, this number has gone up to 61 per cent. In 2018, out of the 32 locations monitored, 28 per cent exceeded the standard during the same time. The highest it went was 44 per cent on April 2 and 4, 2018.

This is happening even before the health risk from particulate matter could be addressed. A comprehensive action plan will be needed to avert a public health crisis. Heat waves and stronger sunshine increases the frequency of days during summer when ozone begins to cross the standards.

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 to human health. All neighbourhoods of Delhi – rich and poor – and even open spaces, are at risk. Delhi and NCR need 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 diseases. 

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