Over the past decades, outdoor Air Pollution has become a leading cause of concern globally. In South Asia, it has been identified as the primary cause for millions of premature deaths in 2015. Air pollution levels (PM2.5, particulate matter with a size less than 2.5 micrometres) in most of the Indian cities are far beyond the World Health Organization’s guidelines of 10 micrograms per cubic metre (µg/m3). In 2016, 18 of 25 most polluted cities in the world were in India.

Air pollution affects everyone and can be linked to several adverse health effects. Sources like on-road vehicles, biomass burning for cooking, solid-waste burning, crop burning and industrial emissions have been identified as major contributors. Mitigating these pollutants at source may not always be within individual capacity and would require action from various stakeholders and policymakers.

The centre’s recently launched National Clean Air Programme (NCAP) attempts to achieve this by calling for a collaborative and participatory approach to focus on all sources of pollution, with a time-bound national-level strategy. NCAP sets a target of 20-30% reduction of PM2.5 and PM10 by 2024, with 2017 as the base year for comparison. To achieve such comprehensive actions for prevention, control, and abatement of air pollution, NCAP requires detailed knowledge of data, research findings and time-to-time policy impact analysis.

Urging participation from relevant central ministries, states, local bodies and other stakeholders to understand source contribution, NCAP identifies the need to implement control strategies at local and regional level. However, currently available knowledge on the sources of air pollution is inadequate to inform such contributions, particularly at local scale, which is a crucial input for developing city-centric strategies.

In today’s scenario, newer studies are being released at regular intervals on various platforms, analysing and discussing source contribution towards air pollution in Indian cities. It is not unusual for these reports to contradict each other—citing different data for the same location in almost similar timelines and drawing different inferences. Gaps in input data and data access constraints to the scientific community are common, and could play a major role in delivering dissimilarities in studies. For better implementation of NCAP, there is a need for researchers and policymakers to access robust, open-source data. India needs to develop a platform for reliable and timely data sharing, to understand source contribution and evaluate policy impacts at local and regional scale.

Emissions inventory, air pollution modelling, ambient air quality monitoring, chemical characterization of pollutants and source apportionment studies are some of the conventional measures to understand source contribution and evaluate policy impacts. Today, except for Delhi, most Indian cities and regions lack such measures. There is minimal knowledge available for rural areas.

The government needs to focus on collating a local and regional database for different sectoral activities (like vehicle kilometre travel, biomass use, industrial energy use) as primary inputs for developing an ‘emission inventory’. To develop an accurate emissions inventory, there is a need to calculate the emissions rate of various activities. Emissions rate or emissions factor is a representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an associated activity. For example, a 20-year-old Indian diesel passenger car emits 0.145 gm of PM every kilometre travelled. Currently, most of the activity-based emissions factor used by India is developed outside the country, which may give erroneous results. India needs to develop its own emissions factor database relevant to local air pollution sources and activities.

Air pollution monitoring network plays a crucial role in identifying problem and evaluating policy impacts. Today, monitoring stations are far below the numbers required, and many existing ones are under stress due to external issues in the process of collecting data, like lack of electricity supply, inadequate workforce to handle and calibrate the monitoring instrument, etc.

For monitoring air quality, ample workforce and proper training for handling equipment, installation, time-to-time calibration and data analysis, are mandatory. There is minimal knowledge of source apportionment studies in Indian cities, thanks to limited expertise and resources. For effective implementation of NCAP, this is as an immediate focus area to improve.

Finally, a majority of monitoring stations in India are in cities, and there is limited or no information available for rural areas. At the policy and scientific front, air pollution has so far been perceived as a problem of urban India and hence no rural-focused policy has been developed. According to the Global Burden of Diseases report, air pollution levels in urban and rural India are unsafe, with 75% of indoor air pollution-related deaths being reported from villages.

It is crucial to perceive this as a rural and urban crisis while studying, monitoring and developing mitigation measures. Geographic locations, location-wise sources of pollution, dispersal of pollutants across regions and other factors should be considered. These steps will help build a systematic mitigation plan by setting up priorities at different scales and as per different regional requirements.

Ajay Singh Nagpure is head of the air pollution programme at WRI India Ross Center for Sustainable Cities