Besides the measures taken and their effectiveness in countering Delhi’s air pollution, the air quality index (AQI) monitoring system has also come under scrutiny due to significant discrepancies between the figures reported by the Central Pollution Control Board (CPCB) and those from the international sources, like Swiss air technology company, IQAir.
According to CPCB data, Delhi’s AQI has typically remained below 500. However, IQAir reports AQI values consistently above 1000, with some readings reaching as high as 1500.
Gufran Beig, founder and project director of the SAFAR (System of Air Quality and Weather Forecasting and Research) under the Union government, clarified that both sets of data are based on the same underlying data set of particulate matter (PM) concentrations, but the methodologies for calculating AQI differ significantly.
The primary difference lies in the guidelines followed for AQI conversion. While CPCB follows Indian standards, IQAir adheres to WHO guidelines, which are stricter. For instance, under Indian standards, PM 2.5 levels of 60 micrograms per cubic meter correspond to an AQI of 100, while WHO guidelines would categorise 50 micrograms per cubic meter as 100 AQI.
Furthermore, CPCB’s calculations are based on 24-hour average concentrations, while IQAir reports AQI more frequently, which can lead to significantly higher readings.
Beig also highlighted a glitch in CPCB’s software.
“CPCB puts a cap on the AQI, limiting it to 500. This means that even when concentrations exceed 500 micrograms per cubic meter, the AQI cannot go higher,” he explained.
In contrast, the average AQI, based on 24-hour data, may still reflect more severe pollution levels than the hourly calculations show. As a result, CPCB’s data often underrepresents the true air quality during times of extreme pollution.
The discrepancies have sparked confusion. While IQAir’s figures have been questioned for being exaggerated, Beig clarified that these numbers, which often exceed India’s AQI limit of 500, do not follow Indian guidelines. “Indian AQI will never go above 500,” he said, adding that while the glitch in CPCB’s software may affect the final outcome, it does not significantly impact the overall system.
On November 11, for instance, the AQI was recorded in the ‘severe plus’ category. However, the official declaration of a ‘severe’ category by evening was delayed, which Beig noted could have further delayed the implementation of measures under the Graded Response Action Plan (GRAP).
The placement of Monitoring Stations
Akash Vashishtha, a Delhi NCR-based environmental expert, says that for real-time figures AQI monitoring stations across the region need to be upgraded and revamped.
Monitoring devices installed by private bodies/institutions provide accurate figures while government-installed devices provide AQI figures up to a certain limit due to their older version. If upgraded and advanced devices are set up, the AQI of the entire area will be quite high in comparison to the current figures shown at various stations.
Secondly, the majority of stations have been set up in residential areas while they should be located in industrial, commercial, market places, crowded places, major traffic junctions etc. AQI in residential areas always becomes low in comparison to industrial and commercial belts.
Besides this, AQI stations should be placed in villages so the authorities can know the reason for low and high AQI. It will be easy to compare the cause of low AQI and access to the infrastructure required in urban areas by comparing them with rural areas.
Apart from this, the need of the hour is to set up more and more AQI stations, increase green cover and use water sprinklers/guns. Usually, we see the use of water sprinklers in the vicinity of AQI stations and no such arrangement in busiest and vulnerable places.
The agencies wanted to bring down the AQI figure but the entire practice does not provide relief to the people. The responsibility of authorities should be fixed as they do not use environmental cess/compensation considering the requirement.
Delhi has a total of 40 air quality monitoring stations spread across the city that are used to calculate the average AQI of the capital. However, these are not evenly spread, with many densely populated areas off the radar and several stations located in inhabited areas.
For instance, the Shri Aurobindo Marg station is located inside the premises of the National Institute of Tuberculosis and Respiratory Diseases situated in the Mehrauli reserve forest range. This is despite the fact that there are several densely populated localities like Lado Sarai and Saidulajaib in close proximity.
Another monitoring station, Dr Karni Singh Shooting Range is located within the Asola Bhatti Forest Range despite the proximity of densely populated Sangam Vihar and Deoli. Yet another monitoring station in South Delhi is located at Siri Fort, next to the Hauz Khas forest.
Nehru Nagar station is situated on the grounds of Delhi University’s PGDAV College. The neighbourhood comprises slums and builder flats which make it a decently populated area.
The busy ring road that connects South East Delhi to Delhi Noida Direct Flyway and Ghaziabad via Sarai Kale Khan is hardly a few meters away from the monitoring station, which explains the high concentration of PM 10 and 2.5 in its readings with the source being vehicles.
However, according to the experts, the exact placement of the AQI station is questionable since it has been situated in the open ground of the college that is surrounded by a decent vegetation cover.
“It’s like a park. It’s unlikely that the monitoring station would reflect a true picture of the concentration of pollutants in the vicinity. The vegetation cover would absorb PM 2.5 and PM 10 suspended in the air as well as sulphur and other emissions emanated from combustion,” said Vashishtha.
Is cloud seeding a viable solution?
Even as the government has taken some desperate measures in the past few years, one such step which is much talk about is ‘artificial rain’. The Delhi government has been contemplating cloud seeding as a potential solution to the city’s air pollution problem.
Delhi Environment Minister Gopal Rai has urged the Centre to convene an urgent meeting with stakeholders to evaluate the feasibility of cloud seeding technology. However, it is pertinent to mention here that the implementation of the cloud seeding technology requires clearance from various Central government agencies.
So what is cloud seeding? In theory, the concept involves using artificial rain to wash pollution particles from the air, a method that could help during the winter months when air quality worsens.
But can it be a solution for Delhi? The first obstacle that any government would have to face is that cloud seeding technology is not a cost-effective method. Moreover, the pollution levels remain high in the capital for almost 4-5 months and tackling the problem through artificial rain can be very expensive.
Let’s understand it through an example: the city residents must have always seen the air quality improving after a brief spell of rain. Developed countries that use this technology to control air or dust pollution have got the same results. The problem is the episodic effect of artificial rain.
The pollution levels again rise within a few days of the rain. But the results seen at other places cannot define the success rate of artificial rain in Delhi, until and unless it is not fully implemented.
Although the Delhi government has considered using artificial rain (cloud seeding) as a potential solution, experts are raising concerns about its feasibility. Gufran Beig explained why this plan may not be practical.
He believes that cloud seeding, while theoretically possible, is costly and complex. “You need clouds to seed. Without clouds, there is no possibility of rain,” he explained.
Moreover, cloud seeding works only with certain types of clouds, which are not typically present during the current season. He also pointed out that the technique is highly localized - rain may occur in a small area, but water molecules can drift to nearby regions, leaving the initial area dry.
“Artificial rain is not magic. It requires careful consideration before execution,” Beig concluded.
Dr Ravindra Khaiwal, a top environmental health scientist in the country working as a professor with PGI Chandigarh said the suggestion of cloud seeding or artificial rain as a “quick fix” for Delhi’s air pollution crisis needs to be scientifically explored as it has the potential to pose long-term environmental risks.
He cautioned that the silver iodide, used in cloud seeding may trigger another environmental and health hazard for the targeted population.
“The idea of washing away pollutants with artificial rain seems appealing, but it may fail to address the root causes of air pollution and could inadvertently introduce new ecological challenges. For instance, silver iodide, a key agent used in cloud seeding, has the potential to accumulate in water bodies, soil, and sewage systems. The long-term ecological and health implications of this accumulation are not fully understood. Furthermore, current research on the bioaccumulation of these compounds within the food chain, as well as their potential impact on human health through drinking water, remains limited,” Khaiwal said.
He pointed out that cloud seeding requires specific meteorological conditions to be effective, which is inconsistent in Delhi’s case, making it an “unreliable and inconsistent solution” to the city’s persistent pollution problem.
Way forward
Khailwal stressed that rather than pursuing temporary and potentially harmful interventions, the focus should shift to sustainable and long-term strategies.
According to Khaiwal, Delhi’s pollution crisis is regional so solutions must come from addressing the root causes of pollution in the city which majorly are transport, construction activities and industries.
“The success of the Delhi Metro shows that people will embrace clean alternatives when they’re efficient and accessible. But more needs to be done in the transportation sector, because other global cities battle primarily with vehicular emissions, Delhi’s million vehicles compete with multiple pollution sources for the position of number one polluter in the city. With a push toward electric vehicles being accelerated, we importantly, need to put a cap on the number of vehicles a city can cater to and need to reimagine urban mobility,” he explained.
“The current system of environmental compensation charges, ranging from a few thousand to a few lakh rupees, has become merely a cost of doing business for polluters. Instead, penalties should be linked to a percentage of annual turnover, making non-compliance financially unsustainable.
Personal liability must extend to company directors and senior government officials who fail to enforce pollution control measures,” he added.
For construction and industrial pollution, Khailwal suggested that real-time pollution monitoring data from industrial units and construction sites should be mandatorily linked to their operating licenses, with automatic suspension triggered by consistent violations.
“Government officials failing to act on documented violations should face departmental inquiries and suspension,” he added.
Khaiwal said that even though Delhi’s air crisis is a regional issue, it requires regional cooperation.
“The recent implementation of the Graded Response Action Plan (GRAP) has utilized an airshed approach, considering the entire NCR and adjoining areas as one unit, but its success depends on coordinated action across state boundaries. The Commission for Air Quality Management’s powers under Section 12 of the CAQM Act must be wielded with stringency,” he added.
The message is clear. Delhi’s pollution crisis needs more than quick fixes.
Sustainable solutions and regional cooperation, backed by strict accountability, are the only way forward.
Long story short
The primary difference lies in the guidelines followed for AQI conversion.
CPCB follows Indian standards, whereas IQAir adheres to WHO guidelines
Similarly, CPCB’s calculations are based on 24-hr average concentrations
However, IQAir reports AQI more frequently
Also, CPCB puts a cap on the AQI, limiting it to 500.
This means even if concentrations exceed 500, the AQI cannot go higher
Cloud seeding, no magic Pill
Cloud seeding is not a cost-effective method.
It can become very expensive if the process has to be repeated multiple times
Cloud seeding works only with certain types of clouds
And, they are not typically present during the current season.
Further, the technique is highly localised - rain may occur in a small area
Also, the long-term ecological and health implications of key agents used in cloud seeding are not fully understood