Since 2013, Delhi's NO2 levels have exceeded the CPCB's annual average limit
Nitrogen Dioxide (NO2) levels that have recently been recorded in Delhi, Uttar Pradesh and Rajasthan, point towards the deteriorating air quality and the need to take immediate measures to improve the situation. As per reports, the three territories have breached the Central Pollution Control Board safety limits in November 2021, sounding an alarm over the air quality and consequently, people's health. Notably, NO2 is one of the primary causes of acid rain, detrimental to nature, property as well as human health.
Monitoring sites in Delhi exceed CPCBs prescribed NO2 mark
Despite switching to renewable sources of energy and the implementation of several EC policies, pollution control strategies, the NO2 component of air has risen significantly to hazardous levels in Delhi, UP and Rajasthan. As per reports, the National Capital has not been able to meet the CPCB's annual NO2 average even once since 2013.
This means, that Delhi has exceeded the CPCB 40 micrograms per metre cube mark for seven consecutive years. The term also includes the COVID lockdown era in 2020 when Delhi's annual NO2 average remain at 61 micrograms per meter cube.
As of November 2021, about 15 out of 40 monitoring sites in Delhi recorded the daily average for NO2 over 80 micrograms per metre cube, while the other 18 sites recorded annual averages above the 40 micrograms per metre cube safety limit for NO2 set by the CPCB, through the month. To put things into perspective, WHO limits the annual NO2 average at 10 micrograms per metre cube and daily at 25 micrograms per metre cube.
Rising NO2 levels in Uttar Pradesh & Rajasthan
The NO2 spike has been diffused over to the adjoining Uttar Pradesh as well. Of the 17 cities in India's most populous states, about 11 have breached the annual NO2 average set by CPCB, read reports. These include the districts of Varanasi (41), Noida (57), Muzaffarnagar (52), Meerut (59), Lucknow (58), Kanpur (62), Greater Noida (65), Ghaziabad (70), Firozabad (47), Bulandshahr (59), and Baghpat (60).
A similar threat looms over Rajasthan as well. As per reports, the desert state has just 10 monitoring sites, across 8 cities. About 50% of these have experienced days where NO2 levels crossed daily averages. These include RIICO Industrial Area in Bhiwadi, Collectorate in Jodhpur and Ashok Nagar in Udaipur. Notably, the capital city Jaipur has three monitoring sites, two of which - Police Commissionerate and Adarsh Nagar are included in the aforementioned index.
Impact of NO2 on the environment and human health
Director, National Institute for Implementation Research for Non-Communicable Diseases (under the ICMR), Dr Arun Sharma, said: "NO2 as gas has not so serious effects on the health of the people, but it's secondary effects through an increase in PM2.5 concentrations and augmentation of Ozone formation are a matter of concern. The average NO2 concentration is higher than the CPCB prescribed limit for all these cities in November 2021. The only way that the NO2 levels can be controlled is by reduction at source, as fixation of NO2 in the air along with SO2 is cause for acid rain."
Medical experts have also pointed out that breathing air that has a high concentration of NO2 can cause irritation and spike the fear of respiratory problems. Such exposures over short periods can aggravate respiratory diseases, particularly asthma and cause inconvenience such as coughing, wheezing or difficulty breathing among people. Long term exposure can develop vulnerability to respiratory problems, leading to new medical conditions.