Screen Shot 2015-12-14 at 1.02.43 PMDr. Sarath Guttikunda is Director of the independent research group and an adjunct associate professor of the Center for Climate Studies at the Indian Institute of Technology (Mumbai). His research interests are in studying the impact of emissions at urban, regional, and global scales, using model and survey tools at various complexities. For recent reports/papers, refer to

The following Q&A with Dr. Sarath Guttikunda is exclusive to                                                                                                                 __________________________________________________          

What causes the air pollution in Delhi?

The air pollution problem in Delhi is seasonal and complex. We have the wintertime highs and the summertime lows. This also goes hand in hand with the media coverage.

Major sources of air pollution, especially for the particulate matter, are vehicle exhaust, industrial combustion (including brick kilns and power plants), residential cooking and heating, diesel generator sets, open waste burning, and dust from various activities (natural and fugitive). Of these, emissions from residential heating, open waste burning, and brick kilns are notably higher in the winter months. Also, in the month of November, there is field residue burning for 1-2 weeks in the Northern states, which further increases the emissions and the consequent pollution levels in the city, during this period.

While the emissions scenario is known to worsen the pollution levels in the winter months, the meteorology also plays its part. The air is notably compressed with the mixing heights dropping down to less than 100 meters (as compared to more than 2000 meters in the summer months), which further exacerbates the pollution levels.

Has it always been this bad?

Anecdotally, what we are seeing today is the level of pollution observed in the city, before the compressed natural gas was introduced. Although, there is very little monitoring data from the late 90s to conclusively say it.

The PM2.5 concentrations in the last four years followed a similar trend, with the winter month averages of 250 micro-gm/m3 and overall annual averages of 150 micro-gm/m3. See the graph below, which shows the average of measurements from the four monitoring stations operated by the Delhi Pollution Control Committee. World Health Organization guideline for PM2.5 is 10 micro-gm/m3 for an annual mean.

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Will it get worse in the future?

Hopefully not if the pollution sources can be systematically addressed to control the emissions. For example, in the transport sector, periodic improvement in the fuel quality between 2000 and 2014 led to some reduction, besides the reductions from converting buses, autos, and taxis to run on compressed natural gas; in the residential sector, penetration of liquefied petroleum gas and electricity usage led to some reduction from cooking activities; in the industrial sector, relocation of the clusters led to some reduction

Will the Delhi Government’s new rule to allow only odd-numbered license plates to drive on the roads one day and even-numbered ones the next, help alleviate air pollution caused by traffic?

Data says not as much as we anticipate, for the following reasons:

  1. This rule is applicable for private vehicles – 4-wheeler vehicles with nearly 70% running on petrol and 2-wheeler vehicles which exclusively run on petrol. We know that most of the PM2.5 emissions in the transport sector come from diesel combustion and we are not addressing it here.
  2. The overall public and paratransit system is not at full capacity to absorb the likely shift of this rule. We estimate a need for more than 13,000 public transport buses for safe, comfortable, and reliable travel in Delhi – for operations under this rule and otherwise through the year.
  3. We are forgetting that the road transport is only a part of the air pollution problem in the city and of that, the private vehicles a small share. According to the central pollution control board study to apportion pollution sources, road transport accounts for 9-21% of the measured PM10 pollution in the city. We are waiting for results from a new study conducted by the Indian Institute of Technology, Kanpur, which is likely to put the shares in the same ballpark.
  4. Having said that, if we successfully cut the use of private vehicles during the daytime, we are anticipating a substantial decrease in the vehicle share of ambient PM2.5 during the day, partly due to the fact that there will be lesser private vehicles and partly due to reduced congestion on the roads. We are eagerly awaiting the test to start and how the implementation will be between Jan 1-15, 2016.

What measures could make a big difference?

As pilots or experiments, these one-off measures like odd/even rule for private vehicles, truck banning, and age limits, are helpful. However, air pollution needs to be tackled at the policy level first. One-off measures that place the burden on the consumers alone will not have as wide-reaching impacts as a concerted effort at the top (the management) and the bottom (the public). We need solutions where decisions can be taken and implemented in a decent time frame, and not depend on the consumer or enforcement for its success. For example

(a) Supplying clean fuel for all vehicles and all India (from 2Ws to heavy-duty trucks), in which we don’t need to worry about who is driving and when. Currently, Bharat-IV fuel is available in Delhi and Bharat-III outside. Almost all the trucks delivering goods in the city or just passing through are likely to use the lower quality fuel available outside the city and pollute the city. A unified and expedited “one nation, one fuel” strategy and a better standard fuel will help reduce the emission burden from the road transport sector.

(b) Supplying clean and reliable power for all (from households to shops to industries), will cut down any need for diesel generator sets or any other fuel for combustion in the industries. This can also include promotion of renewable energy, especially small scale at the residential sector or in the telecom sector (the telecom towers are the largest consumer of diesel outside the road transport, catering to nearly 1 billion people across the country).

(c) Pick up and manage every kilo of waste generated; knowing that any kilo of waste not picked up, has the potential to burn. Data says that the city produces nearly 11,000 tons of waste per day, with a landfill catering facilities for 7,000 tons of waste per day. This can include educational programs to not generate waste, segregation of waste at the source and at the landfills to recycle and reuse, and stricter regulations to control burning of waste.

(d) Dust free and pothole-free roads. Though dust control has limited benefits to the PM2.5 fraction, it is a major component (and still harmful) of the PM10 fraction. The programs to vacuum clean all the roads, pave all the roads, and wet sweep the dusty unpaved roads, will help to control this source.

(e) Improving service in public, para, and non-motorized transport (walking and cycling) sectors. This needs infrastructure support from the Government and public awareness campaigns to make a successful transition from dependent on private vehicles to sharing the road space.

(f) Most of the power generation in the city is based on natural gas. The city grid also draws from power plants 200 km away, all of which operate on coal. These plants are close enough to occasionally influence the air quality in the city. This can be reduced by implementing stricter norms to control particulate matter, sulfur dioxide, and nitrogen oxide emissions at these plants, which currently lags behind the international practices.

(g) Of the seasonal problems, the brick kiln technologies can be refurbished, with minimal infrastructure changes, from the current fixed chimney bull trench kilns to fixed chimney zigzag kilns, with better heat transfer rates. This requires an intervention from the city and central authorities to mandate a technology change and likely support to the kiln operators to aide the transition.

 What next steps are needed to help policy-makers make the best-informed decisions?

Most importantly two things:

(a) Dramatically improve the monitoring capability in the city and in the satellite cities (Gurgaon, Noida, Greater Noida, Ghaziabad, Faridabad), so that we know exactly how much is the pollution, where is the pollution, and where it could be coming from; and disseminate the monitoring data in real time, as both absolute numbers and as health alerts for everybody to see and take precautions, if necessary. This could go hand in hand with the practice of emergency measures, in case of serious health alert situations.

(b) We all are in agreement that the pollution crisis is real and present, and needs immediate attention. So, make the pollution control plan at the sectoral level, by understanding the role of each contributing sector to the problem.

Thank you, Dr. Guttikunda, for sharing your insights and time with and our friends and followers.