1) Air pollution is referred to any contamination of the indoor or outdoor environment that modifies the characteristics of the atmosphere. Although more research is required to further understand the role poor air quality and multi-pollutant exposure plays in health. According to the World Health Organization (WHO) in 2012, an estimated 6.5 million deaths were associated with indoor and outdoor air pollution together, this r4epresents 11.6% of all global deaths.
Major sources of air pollution vary from country to country and in every city, depending on their infrastructure and industrial activities, but in general, common sources include motor vehicles, household combustion devices and waste burning, coal-fired power plants, and industrial activities.
Pollutants of major public health concern include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide. (EPA)
The most relevant issue in this problem is that once the pollution has been produced it is very difficult to clean because of dispersion, and while reducing the pollution production is a relatively simple solution ( through filters and catalytic combustion, etc) once the pollution is diffused in the environment, it becomes a very complex problem to solve, mainly because of the dimension of it. In other words, it is impossible to clean all the air in the atmosphere.
2)Nonetheless, China is investing a large quantity of money to fix this difficult problem, and many innovative solutions are being implemented, such as air purifiers the size of buildings, or mist cannons that nebulizer liquids to trap harmful particles, but still, these solutions face the great challenge of diluted pollution and large dimensions.
A novel solution that is being tried is the smog-busting drones, the idea is to use drones to spray chemicals [liquid nitrogen], to solidify pollutants in the air and fall to the ground.
“When liquid nitrogen is dispersed in air, it readily absorbs heat from the surrounding atmosphere, causing water vapor to instantly condense. The condensate would drag down particulate matter along with it as it falls to earth” Emily Carino-postdoctoral researcher in chemical engineering with a PhD from the University of Texas
The chief executive of the company, Ma Yongsheng, he explained that drones have a reach of 5km and can carry 700 kg of smog-clearing chemicals, and have conducted over 100 hours of testing flight. [South China Morning Post]
Nonetheless, there is a big international opposition to this approach of geoengineering, mainly because of two postures, exposed by Emily Carino, from the University of Texas.
The first one is the effect that this chemical rain can have on citizens. “Used improperly, liquid nitrogen is dangerous: It can cause severe cold burns if it comes in contact with skin, and items cooled by liquid nitrogen can stick fast to human skin when touched.”
And the second is the risk of the unintended consequences of such chemical reaction, not only because the reaction occurs so quickly, but also because nitrogen outperforms all other agents during the reaction.
3) This technology is mainly to be deployed by the government since air pollution or air quality is a public good.
4) The steps to deploy this technology are to run a pilot and have an important and solid baseline to compare the improvements as well as the unintended consequences.
Nonetheless, I am very skeptical about the impact of this technology application due to the unintended consequences, and most importantly it is important to point out the irrational thinking of creating rain from pollutants, instead of deploying filters and air pollution control systems in the industry and combustion vehicles.