Kolkata has witnessed a significant rise in ground-level ozone pollution despite a notable reduction in fine particulate matter (PM) pollution, according to an analysis conducted by Climate Trends. The city recorded the second-highest levels of ground-level ozone among Indian capital cities, surpassed only by Mumbai. The study evaluated air quality in seven major Indian cities — Delhi, Chandigarh, Lucknow, Varanasi, Patna, Kolkata, and Mumbai — focusing on the concentrations of key air pollutants including PM2.5, PM10, NO2, SO2, CO, and ozone from January 1 to February 29, 2024.
Ground-level ozone is formed through complex chemical reactions involving nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. Major sources of VOCs include vehicle emissions, industrial processes, and vegetation. Ozone exposure can irritate the respiratory system, cause coughing, throat irritation, and exacerbate asthma and other respiratory conditions. Prolonged exposure may lead to lung inflammation and reduced lung function. Ozone also poses a threat to vegetation, reducing crop yield and forest productivity, and contributes to the degradation of materials like rubber and plastic.
Monitoring ozone levels is crucial to understanding the photochemical processes driving its formation and identifying sources of precursor pollutants such as NOx and VOCs. This monitoring is also essential for assessing the effectiveness of emission control strategies in reducing ozone concentrations.
A professor at Venkateshwara College, University of Delhi, emphasised the need for a comprehensive approach to improving air quality. “Improving air quality requires addressing a variety of pollutants and their origins to effectively protect public health and the environment. This approach also aids in understanding sources within the region,” he said.
A multipollutant analysis is essential for comprehending the complexities of air pollution and its impact on public health and the environment. Air pollution consists of a mixture of pollutants from various sources, including vehicles, industries, and natural origins. A multipollutant analysis examines the interactions and synergistic effects among different pollutants, providing a more comprehensive picture of air quality.
Despite the drop in particulate matter, Kolkata’s surge in ground-level ozone underscores the challenges of tackling air pollution. The rise in ozone levels indicates that while efforts to control PM levels may be effective, other pollutants continue to pose significant risks. The findings highlight the necessity for holistic air quality management strategies that address all major pollutants and their sources.
The Climate Trends analysis reveals that tackling air pollution requires multifaceted strategies and a deeper understanding of regional pollution sources. As cities like Kolkata strive to improve air quality, comprehensive and integrated approaches are vital to ensure effective mitigation of all harmful pollutants, thereby safeguarding public health and the environment.
