Over the Diwali weekend of 2016, India’s air quality was among the world’s worst and between 40% and 100% worse in five north Indian cities than at the same time the preceding year, according to global air pollution data and an IndiaSpend analysis of national data and our #Breathe network of sensors.
On October 30 and 31, 2016, from 9 pm to the wee hours of the next morning, North India–especially parts of Delhi, Uttar Pradesh and Bihar–recorded PM 2.5 levels of over 500 µg/m³–exhibiting “beyond scale” pollution values, according to the database run by Berkeley Earth, an independent US research organisation. Represented through heat maps, the database typically records the world’s worst air quality–at the top of the scale, most between “very unhealthy” to “hazardous”–in dust-blown Xinjiang province in northwest China and parts of North India.
PM 2.5 is fine particulate matter about 30 times finer than a human hair. These particles can be inhaled deep into the lungs, causing heart attacks, strokes, lung cancer and respiratory diseases, and are known to pose the greatest risk to human health. Their measurement is considered to be the best indicator of the level of health risks from air pollution, according to the World Health Organization (WHO).
For this analysis, IndiaSpend compared 2016 Diwali air-quality data (October 23 to November 1) from our #Breathe monitors–in Lucknow, Agra and Varanasi in Uttar Pradesh, Patna in Bihar, and two locations in Delhi–with air-pollution data recorded by the Central Pollution Control Board (CPCB) in similar locations over the same Diwali period (November 4 to 13) in 2015.
South Delhi’s 24-hour average PM 2.5 levels in 2016 were 38% higher than on Diwali night 2015. The next day, these levels were twice as high as the day after Diwali in 2015, crossing 650 µg/m³, 26 times above the WHO’s guideline levels, or levels considered safe. On the morning of November 1, 2016, citizens in Delhi woke up to an average PM 2.5 level of over 700 µg/m³–some of the highest levels recorded the world over and 29 times above WHO standards.
The WHO guideline for 24-hour average PM 2.5 levels is 25 µg/m³. With an annual average PM 2.5 level of 122 µg/m³, Delhi’s air is the worst among global megacities with dense populations, as IndiaSpend reported in October 2016 based on WHO data.
The CPCB sensors were located within a 5-km radius of our #Breathe. We observed that for the week ending October 30, 2016, PM 2.5 levels recorded by the CPCB monitors were lower than those recorded by #Breathe sensors in many instances. This variance could be attributed to the difference in location and other local climatic factors. However, the trends of variation in PM 2.5 levels over the week are similar, as the graph below indicates.
