The following is accurate according to an [scientific report][1] published in Nature:

> Nature 525, 367–371 (17 September 2015) The contribution of **outdoor air pollution** sources to premature mortality on a global scale doi:10.1038/nature15371
Received 10 May 2014 Accepted 27 July 2015 Published online 16 September 2015. http://www.nature.com/nature/journal/v525/n7569/full/nature15371.html


Scientists from Harvard University and other countries such as Cyprus and Germany measured the most detailed estimates yet of the toll of air pollution, in a quest to find the cause. The study found that outdoor air pollution is killing **3.3 million people a year worldwide**, that is divided as such:

 - China: **1,400,00 deaths/year.** <br>
 - India: **645,000 deaths/year.** <br> 
 - European Union: **180,000 deaths/year.** <br>
 - Pakistan: **110,000 deaths/year.**  <br />
 - United States: **54,905 deaths/year.** <br />

The Guardian also [reported][2] that study:

> **is the first study to single out different outdoor air pollution sources** and estimate the number of premature deaths they each cause, considering road traffic, fossil fuel power stations and other sources. 

Furthermore, **[global WHO estimates suggest][3]** that the result of the scientific report published in Nature is accurate:

> Regionally, low- and middle-income countries in the WHO South-East Asia and Western Pacific Regions had the largest air pollution-related burden in 2012, with a total of:  <br />
    - **3.3 million deaths** linked to indoor air pollution. <br />
    - **2.6 million deaths** related to outdoor air pollution.

As you see:

 - WHO estimated in **2012 that 2.6 million** **deaths** are related to outdoor air pollution.  

 - Nature study estimated in **2015 that 3.3 million deaths** are related to outdoor air pollution. 

Note that the The Nature study did not measure **indoor air pollution**, which obviously mean, according to the WHO estimate, that more deaths/year could result from **indoor air pollution**. Here is a list of caused/deaths published in [WHO][3]:

> **Outdoor air pollution-caused deaths:** <br>
> 40% – ischaemic heart disease;  <br>
> 40% – stroke;  <br>
> 11% – chronic obstructive pulmonary disease (COPD);  <br>
> 6% –  lung cancer;  <br>
> 3% –  acute lower respiratory infections in children.  <br>

> **Indoor air pollution-caused deaths:** <br>
> 34% - stroke;  <br>
> 26% - ischaemic heart disease; <br>
> 22% - COPD;   <br>
> 12% - acute lower respiratory infections in children;  <br>
> 6% - lung cancer.  <br>

The Nature study also predicted that the yearly death total will double to about 6.6 million a year by 2050. 

**To sum up:** 1.4 million Chinese people die yearly due to outdoor air pollution. WHO suggests that a *large number* of Chinese people die from indoor air pollution too. 


  [1]: http://www.nature.com/nature/journal/v525/n7569/full/nature15371.html
  [2]: http://www.theguardian.com/environment/2015/sep/16/more-people-die-from-air-pollution-than-malaria-and-hivaids-new-study-shows
  [3]: http://www.who.int/mediacentre/news/releases/2014/air-pollution/en/