# How Can Smog in Metropolitan Cities like Delhi & Beijing Be Reduced?

These two cities are facing the worst smog in Asia and I think in the world and people of these cities have no choice other than to wear masks when going outside. So what Advance technology that can be used by these two state government so that smog can be reduced to a minimum or can be eliminated?

these 2 counties can't avoid smog due to large no. of factories and farmer burning residual so what Technology that can be used to reduce/eliminate smog.

• I downvoted this question because it shows you have not down research on this subject. If farmers in Punjab and Haryana stop burning their crop stubble the pollution would be reduced by half. If this is wrong then please display data that shows the city of Delhi itself produces this smog on it's own. – gansub Nov 11 '17 at 8:59
• scroll.in/roving/1588/… – gansub Nov 11 '17 at 9:07
• @gansub: News articles (e.g. newsweek.com/united-cancel-flights-delhi-air-pollution-708961 ) put Delhi smog levels at 40 times safe levels. If half of it comes from the farmers burning stubble, then if that's stopped levels would still be 20 times safe levels. – jamesqf Nov 12 '17 at 6:36
• @gansub i know the farmer reason but that's there best bet(economical) and Punjab and haryana govt doing nothing (not giving any incentive to stop them burning).Delhi minister is fighting this Smog battle all alone even the centre govt has refused the Helicopter facility for sprinkling. u have downvoted for this not cool man !! – Deepak Jain Nov 12 '17 at 12:21
• @jamesqf - it is a holistic thing. If farmers stop burning stubble other good thing follows. What they need is a revolution in thinking and in living. – gansub Nov 13 '17 at 9:58

The first thing to do is to stop putting pollution in the air, particularly very small particulate matter that are produced by combustion.

For the Beijing Olympic Games of 2008, the Chinese government forced the polluting plants and factories in the vicinity of Beijing and nearby areas to stop operating for weeks prior to the games and during the games to ensure the air in Beijing was clear and had minimal pollution during the duration of the games. The measure was successful.

Burning wood, animal dung, coal, petroleum products (particularly diesel and heavy oil) produce soot and other small particulate matter which leads to poor air quality and smog.

This is an easy solution that results in clean air. The difficulty with this is that it is detrimental to the economy in the short term. For a longer term solution, energy sources need to be changed to ones that do not cause air pollution.

• very difficult for Poor country like India(Delhi) to not use coal as India is still developing – Deepak Jain Nov 10 '17 at 15:41
• @Deepak Jain: But "still developing" should mean that India could learn from other countries, and not slavishly follow their bad examples of such things as coal burning. Or indeed, creating mega-cities where pollution becomes a major problem. – jamesqf Nov 11 '17 at 5:43
• @jamesqf ppl are poor in India and Govt does not help them (too much corruptionin Centre govt #Modi). – Deepak Jain Nov 12 '17 at 12:25
• @Deepak Jain: But the advanced methods of power production are often cheaper than more primitive ones. For instance, cars with advanced pollution controls use less fuel, – jamesqf Nov 12 '17 at 19:08

Stop burning fossil fuels. Run vehicles on electricity. Produce electricity using solar/wind/nuclear methods. Develop new methods. Sell methods to other countries. Profit!

• in this question i am asking abt the methods/technology that could be used to reduce smog – Deepak Jain Nov 12 '17 at 11:12
• @DeepakJain are you talking about ways to capture existing smog, or ways to prevent it? – Gimelist Nov 12 '17 at 11:43
• Capture the existing smog over the city – Deepak Jain Nov 12 '17 at 11:44
• India can't avoid smog due to large no. of factories and farmer burning residual so what Technology that can be used to reduce/eliminate smog. when it happens basically a Smog Sucker !! – Deepak Jain Nov 12 '17 at 12:37
• @Deepak Jain: There's no such technology. Even if it were possible, the producing the energy required from coal plants & other dirty sources would most likely create more pollution than would be removed. The solution to air pollution is to eliminate the sources, or perhaps not concentrate 26 million people in an urban area. – jamesqf Nov 12 '17 at 19:12

I add some information here to present the control strategies which have been done by China government.

A series of paper have reported that coal combustion is the main cause of the air pollution in China. This issue usually gets worse in the winter months due to the fact that coal is used for domestic heating.

In the winter of 2017, China government decided to transform the fuel types for each of the residents even in rural areas within north Chian as fast as possible. Here is a figure I captured near my campus, the giant pipes convey the natural gas to each of the residents for heating and other uses.

Although the heating fee might increase, the consumption of coal, especially for those bulk coal (known as cheap with high amount of emissions) was cut significantly. The effects of energy structure adjustment has been observed clearly. As shown in this figure presenting the monthly variations of PM2.5 in 2015, 2016 and 2017, the improvement of air quality is an obvious one. Especially in December when the strict control strategies were implemented, the concentration decreased sharply compared to 2015/2016.

By sharing the example of Beijing, I make a point that the improvement of air quality is possible by applying the current technology. What's more, the movement from traditional fuels to clean fuels seems to be a more efficient approach compared to the end-of-pipe control with advanced technology.

• Good example. Could you translate the text in the figure and provide a link that directs to that figure. I can't find the figure from this link. – Communisty Sep 21 '18 at 13:24
• I'll re-write the figure by myself. – Han Zhengzu Sep 22 '18 at 1:15

There is no technology that makes air pollution disappear on such a large scale after it has already been emitted into the atmosphere. However, timing burns so that air quality impacts are minimized is possible if meteorology is considered. If there is a meteorological forecast that mixing heights will be low, a "burn ban" should be put in place. If mixing heights are expected to be high and/or the wind direction is expected to blow away from the city, then burning could be allowed with minimized effects on air quality in the densely populated areas. This type of practice is used in the USA in various states.

Often the cheapest solution is to prevent pollution (not burn leaves, add filters to factories, etc.), but in many cases pollution can be natural, e.g. fine sand from a desert.
Solar updraft towers are a promising technology that can reduce the pollution near the cities, by creating fast wind which moves the particles to the higher layers of atmosphere. When using the tower only to improve the quality of the air, the greenhouse can be much smaller than the one needed to generate electricity. A small prototype in china have shown sizable improvement in air quality. And here's a link to a more detailed study.