Severe Air Pollution Takes Delhi by Surprise
Health & Environment 03/11/2023 •
Same place two months apart. Above: AQI 78, 8th of September, 2023, below: AQI 479, 3rd November, 2023

Within hours, the Delhi government closed schools and announced traffic and construction curbs, but experts are questioning whether the government is tackling the right causes. Meanwhile, a database reporting the contribution of pollution from farm fires has been discontinued by the national government. The air quality forecast remains bleak.

Delhi’s air pollution suddenly got a whole lot worse on the 2nd of November, hitting the government’s own defined ‘severe’ levels of 379.2 micrograms/m3 of PM2.5 for the 24-hour period. 

Despite rising levels of awareness and preparedness for air pollution emergencies, the deterioration in air quality was not anticipated by the Air Quality Early Warning System run by the Central government. 

Unlike in years past,  officials both at the national and Delhi state level were quick to respond – reflecting the growing awareness of air pollution’s health harms over the past few years. 

Within hours, Delhi’s Chief Minister Arvind Kejriwal closed primary schools, and the national government launched an 8-point plan to curb pollution emissions, including a system of ‘differential’ fares for public transit to encourage off-peak bus travel. 

But despite the measures the latest forecast shows the next few days may continue to see severe air pollution or at best ‘very poor.’ This translates into pollution levels that are roughly eight times the WHO 24-hour average guideline standard for PM2.5 levels, widely regarded as the best indicator of health-harmful pollutants. 

And the immediate outlook remains bleak. ‘Severe or Very Poor’ air quality is forecast for six days starting on the 3rd of November. 

Stubble burning may, or may not, be the leading factor 

Delhi’s haze of 2nd November, 2023: The barely visible building is about 700 metres away, when the hourly PM 2.5 level in this location was a little over 450 micrograms/cubic metre (µg/m3). The WHO’s safe limit for a day is 15 µg/m3.

While many have cited the stubble burning by farmers in rural states north of Delhi, as a key driver for seasonally high levels of pollution in the late fall and early winter, local sources may also be playing a larger role in the leading factor in the current emergency, experts said. 

The fact is that this year, the number of stubble fires burning in Punjab, the state that produces the lion’s share, had declined by about half their seasonal rate, as of the 1st of November. 

In their quest for sources, some experts were now pointing squarely at Delhi and surrounding cities – where cooking from biomass, traffic and industrial emissions may now be the leading factors. 

Additionally, there are the classic weather conditions faced by Delhi at this time of year, when falling temperatures, low wind speeds and a lack of rainfall all trap pollutants closer to the ground. Confounding the issues, one leading government data source on air pollution sources, maintained by the System of Air Quality and Weather Forecasting and Research (SAFAR), has been discontinued, making it more difficult to attribute the sources of pollution at all.

Living in a Haze

On Thursday, the usual morning haze lingered on and appeared to get worse as the day wore on. Visibility fell, and many people complained of sore throats, running noses and fever. Social media was buzzing with pictures and complaints demanding to know how this is allowed to happen year after year. 

Preliminary data shows that levels of PM 2.5, fine particulates that are the most common indicator for health risks, shot up beyond 250 micrograms/cubic metre (µg/m3) on average across India’s capital around 2-3 p.m. Thursday afternoon. That’s 17 times greater than WHO’s 24-hour standard of just 15 (µg/m3) . 

The mid-afternoon spike was also unusual. As it’s the hottest part of the day, pollutants tend to rise with the heat thereby reducing ground-level pollution. 

The pollution emergency was not forecast although satellites and at least one supercomputer are now being used in India to track air quality.

Eight-point graded response plan announced 

The main body in charge of controlling pollution in and around Delhi, the Commission for Air Quality Management (CAQM) blamed meteorological and climate conditions as “highly unfavourable.” The air quality index (AQI) was only expected to worsen in the coming days, it also warned.

As the AQI hit ‘severe’ it triggered multiple responses. Government officials gave the go-ahead for an 8-point action plan – under a programme called Graded Response Action Plan (GRAP). 

Topping the list is more vacuuming and mechanised sweeping of roads and sprinkling water to suppress dust. 

The government also introduced differential rates on Delhi’s public transport system to encourage off-peak travel to reduce traffic congestion.

Bus frequency has also been increased and special shuttles are being started for central government employees, a senior official of the Government of Delhi, Mr Ashish Kundra told Health Policy Watch. 

The Committee also announced a  ban on all construction and demolition projects except for essential hospitals, defence, metro and other infrastructure. 

They announced restrictions on the movement of older vehicles that fail to meet the latest pollution standards within Delhi and four bordering cities (Gurgugram, Faridabad, Ghaziabad and Gautam Budh Nagar a.k.a. Noida.)

Officials Divided: To Walk Or Not To Walk

But there appear to be cracks in the air pollution control system. It goes beyond the well-publicised discussion around a basic shortage of staff. 

In the first 24 hours of the crisis, there’s been contradictory health advice to residents from two top agencies. 

Notably, the CAQM, controlled by the Central government, says those in Delhi and its neighbourhood should “walk or use cycles for short distances.” SAFAR, also controlled by the Central government (they have the said supercomputer), says “everyone” should avoid all physical activity outdoors and “give a miss to walk today.”

Scientists have documented how even short-term exposure to hazardous levels of PM 2.5 are linked to premature mortality, increased emergency room visits and hospital admissions for acute and chronic cardiovascular and respiratory conditions.  As a result they have generally recommended restricting outdoor physical activity on high-pollution days.

Focusing on the wrong pollutants? 

A look at the curbs announced by the CAQM also shows that there is an emphasis on controlling construction and road dust. 

However, the contribution of these sources to Delhi’s current air pollution problem is very marginal, according to daily source attribution data generated by the Ministry of Earth Sciences. 

Known as the Decision Support System for Air Quality Management in Delhi (DSS). This is the one India-based reference point remaining for unraveling air pollution sources following the discontinuation of the SAFAR database.

For 2 November, the DSS showed Delhi’s construction as contributing  2% of ambient air pollution, while road dust and waste burning contributed just 1% each. 

In contrast, the largest proportion of pollution currently was from biomass burning – 25% according to the DSS database. This latter presumably includes the thousands of crop stubble farm fires burning up north in the states of Punjab and Haryana – but it also could include local household sources of heating and cooking. 

Delhi-area transport accounted for about 14%. Meanwhile, another 30% of emissions are transported into the city from 19 nearby towns. 

Another 16% of emissions originate from areas beyond the Delhi region – although there is no further detail on the types of sources here, as well. 

Notably, more precise data on the source apportionment of farm fires used to be provided by the SAFAR database, operated by the Centre’s Ministry of Earth Science, until only a year ago and cancelled for reasons that no one has managed to explain. 

Given a dearth of information about sources, then, major questions remain about how effective are the measures being taken in Delhi in the current air pollution crisis. 

Farm Fires vs Delhi’s Own Pollution

Satellite data shows that the number of farm fires in the north Indian state of Punjab has sharply declined compared to a year ago, but have begun to rise now. Source: CEEW.

Many farmers burn the residual stubble from the paddy harvest in order to sow the next crop, largely wheat, by mid-November. It’s the most economical way specially for marginal farmers to do so given how expensive manual labour or machines are. 

The governing party of Punjab, Aam Aadmi Party (AAP) is also in power in Delhi. It had promised to reduce the number of farm fires by half this year; last year there were almost 50,000. The data so far shows that that seems to be on track. The fire count till the 1st of November, i.e. a day before the air quality turned ‘severe’, was under 9,000 compared to over 17,000 a year ago at the same time.

However, the fires are rising daily. The four-day average till 1st November was 2,200 compared to under 900 a week earlier. The number of fires is expected to rise till mid-November when the wheat must be sowed. 

The smoke appears to be smothering Delhi. While the DSS data showed it was contributing a quarter of the pollution, the EU space programme posted that a “thick smoke blanket (from the stubble fires in the northwestern states) is engulfing” the capital.

Additionally, the CAQM stated that there was a sudden increase in the number of farm fires, combined with unfavourable meteorological conditions (low wind speed) moving pollution to Delhi. 

However, some experts point out that the lower number of farm fires underscores a greater truth. 

“The contribution from fires or any sources will continue to remain debated as there is not a clear consensus on the emissions inventory being used to develop these models” for source attribution. 

“Despite lower levels of burning in the same period this year (vis-à-vis) last year, we see that the AQ is as bad, if not worse than last year, and this points to the other sources that exist within the NCR that need better coordination to address. 

“In two weeks’ time, we will have to shift focus to those more persistent sources that pollute our air throughout the year. The role of meteorology must be discounted at all times- what we cannot control, we cannot obsess over and blame. We can only bring down our emissions,” says Karthik Ganesan, Fellow, Council on Energy, Environment and Water (CEEW.)

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