PM2.5 Data Available for 29% of the Time in Delhi

The backbone of Delhi’s air quality monitoring network is its set of 21 ambient air monitoring stations, 11 of which have data that are accessible to the public. The city’s main air pollution concern is PM2.5, suspended particles small enough to be trapped in the lungs. PM2.5 has been shown to cause lung cancer, cardiovascular and respiratory diseases, asthma, and a host of other health problems.

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Data obtained from the Central Pollution Control Board (CPCB) website for the 11 monitors run by the CPCB and Delhi Pollution Control Committee (DPCC) show that PM2.5 was being recorded only 29% of the time at these sites last winter–the season associated with the most severe levels of particulate pollution. Coverage since March 2015 has increased to 46%, but these gaps in the data make it difficult to reliably characterise the actual air quality situation in the city. Continuing the trend of improvement in coverage should be a high priority.

Coverage patterns show that monitor downtime tends to be concentrated in long stretches, when PM2.5 is not being collected for several months. This could be due to maintenance issues that are not detected or acted upon in a timely manner, pointing to problems with information flows and management within the organisations running the monitors. Paradoxically, these large gaps in data collection may be easier for the CPCB and DPCC to address than if monitors went down more frequently and for shorter periods. Making air pollution monitoring data easier for the public to access would be a good step toward creating the accountability that could help these organisations keep the city’s monitors functioning.

For the quality of air to improve, the quality of information must first rise. With even a rough idea of source apportionment, the government can take actions like shutting down dirty power plants and pushing neighbouring states to better regulate crop-burning. Once the low-hanging fruit is picked, policymakers will need increasingly detailed information on location, source, and type of air pollution to design a smart policy response. Now is the time to get the information systems in place that will inform the next decade of environmental policy in the city, and beyond.