China: The terrible condition of the air in its cities is just one example of how this country, growing at breakneck speed, does not exercise sufficient control over its emissions. Development of this kind must take account of environmental risks, given that in just a few years it has overtaken the United States in terms of tons of CO₂ emitted into the atmosphere.

Top 5 worst countries: http://www.activesustainability.com/top-5-most-polluting-countries

Air Pollution:

• Air pollution is the combination of Carbon dioxide and Methane increasing and so increasing the earth’s temperature.
• It is the most dangerous of all the environmental problems, it kills around 7 million people each year or 1/8 deaths globally.
• Indoor air pollution is the equivalent to smoking two packets of cigarettes a day if you cook and heat your homes using open fires.

What causes it:

• Most of our air pollution is from energy use and the production of it, burning fossil fuels releases gases and chemicals into the air.
• Passenger vehicles is one of the major contributors to our air pollution, they contribute to 75% of our carbon monoxide emissions. In urban areas, it can be up to 50% to 90% of our carbon monoxide emissions.

The effect of Air pollution:

• Carbon monoxide is a odorless, colourless and is poisonous. It is responsible for over 430 deaths a year and the annual death from carbon monoxide for males is 0.22 per 100,000 and for females it is 0.7 per 100,000. 
• Air pollution can induce headaches, nausea and allergic reactions. IT can also aggravate other medical conditions such as Asthma and Emphysema.  
• There are long term effects such as Chronic Respiratory disease, Lung Cancer, Heart disease, and even brain damage. 
• Apart from health effects, Air Pollution can also lead to a variety of environmental effects such as Acid Rain which precipitation containing harmful amounts of nitric and sulfuric acids. 

Smog and Soot:

• Emissions from fossil fuels react with sunlight to produce Smog which is similar to Fog but it thick and stays for days, months or for 365 days a year in places like China.
• Soot, is made up of tine particles of chemicals, soil, smoke, dust or allergens. 

Air Pollution in China in Real Time: http://aqicn.org/city/shenzhen/

December 21 2016: http://learningenglish.voanews.com/a/china-battles-smog-as-worst-air-pollution-of-the-year-hits-beijing-and-other-cities/3645519.html