Delhi set this month a dubious record one of having one the highest air quality index (AQI) of above 500 that put the quality of air its citizens breathe in the  'hazardous' category.  The major reason was said to be stubble burning by farmers in nearby states.  This was exacerbated by dust from construction activities in the National Capital Region, vehicular pollution and temperature inversion.  Temperature inversion together with wind direction flow did not allow the smoke and dust to disperse into the higher atmosphere, thereby creating death-chamber like conditions on the ground. This yearly pollution phenomenon takes place in November after Diwali. 
 
There are enough existing solutions to alleviate air pollution which is a result of a waste-disposal problem.  However, there is a need to have political and administrative will to implement them.  India produces anywhere from 600-800 million tonnes of agricultural residues per year after harvesting of crops.  As the farmer wants his land to be ready for the next crop he has to dispose of these residues;  the fastest way to do this is to burn them in the fields leading to air pollution.
 
In the early 1990s the Nimbkar Agricultural Research Institute (NARI) in Maharashtra had pioneered the concept of using these residues for power generation. Their work showed that every taluka/tehsil (an administrative sub-division in rural areas) had enough agricultural residues to meet all the electricity demands of that taluka.  This work led to a national policy on taluka energy self-sufficiency in 1996. Thus 600-800 million tonnes/year of agricultural residues can theoretically produce about 80,000 MW of electricity.  Besides producing power the selling of residues to power plants can provide extra income to the farmers.  Presently farmers do not make any money from the residues.  For the country as a whole, this extra income for farmers can amount to about Rs. 3 lakh crores and can create substantial wealth in rural areas.          
 
In 1995 NARI also developed the world’s first loose biomass gasifier running on agricultural residues like sugarcane trash, wheat straw and those from other crops.  The gas from 500 kW (thermal) gasifier was shown to be useful for producing excellent heat from community kitchens. The gasification process produces syngas (a mixture of carbon monoxide and hydrogen) which could be used for producing methanol, a useful liquid fuel for transportation. Both these technologies show that agricultural residues could easily be converted into useful products (electricity and liquid fuels) and in the process reduce air pollution.
 
However, for improving the soil so that agricultural productivity increases it is necessary that most of these residues should be plowed back into the field.  No-till agriculture (NTA) allows the incorporation of these residues into the soil while minimally disturbing it. For planting crops holes are drilled into the soil in which seed can be planted and then covered up. This is done by specially designed planters. This way the soil surface remains undisturbed along with the residues from the previous crop. NTA not only improves the soil but the soil erosion is reduced drastically. Since the stubble is not burned, NTA is also one of the best mechanisms to reduce air pollution.
 
NTA is practiced extensively in western countries and farmers are finding it very remunerative.  In India, only in the last 6-7 years NTA has caught up and is being practiced mostly in north India with estimates of about 1.5 million hectares under it.  The reasons for such low-level penetration are non-availability of economically priced planters, not enough publicity regarding the advantages of no-till and non-availability of low-cost weedicides. There are major industrial players producing agricultural machinery in India but somehow no-till machinery is not in their visual fields.  The government should encourage NTA by providing economic incentives to both farmers and agricultural machinery makers.
 
Another method of reducing air pollution in Delhi and other cities is to plant trees on a large scale. Researchers have discovered that if about 20-30% of city area is covered by trees then it can reduce particulate pollution by almost 24%.  In most Indian cities tree cover is between 7-15% and hence there is a need to increase it.  Besides reducing air pollution trees also make up the planet’s heat shield.  They keep the concrete and asphalt of cities and suburbs 4-5 degrees or more cooler and tremendously reduce the air-conditioning load of buildings.    
 
For vehicular pollution reduction, one of the best solutions is to have mobility based on electric vehicles. Electric cars and buses are becoming common in Western countries.  In fact, all major car companies in the world have electric cars in the pipeline.  Electric vehicles not only reduce air pollution but also noise pollution since they are silent.  There is no single solution to reduce air pollution in Indian cities.  What is really needed is the political will to identify innovative solutions and implement them. 
 
(The writer is Director, Nimbkar Agricultural Research Institute, Phaltan, Maharashtra. He can be contacted at anilrajvanshi@gmail.com)