According to the World Health Organization (WHO), 9 out of 10 people are currently breathing in toxic air. Shown to contribute to dangerous magnetites in the brain which could potentially cause Alzheimer’s disease, this toxic air can also cause lung cancer, heart disease, and stroke. What’s more, the report states that more than 6 million people died from diseases related to air pollution in 2012. This is a grand total of 11.2% of all global deaths. 
Researchers at the University of Bath found that 90% of people living in the United Kingdom live with poor air quality, and the worst affected are those that live in Bristol, London, Glasgow, Manchester, and South Wales. This is largely due to the fact that many wealthier countries are using diesel fuel in their trucks, which creates more pollution within the cities themselves. 
It’s Worse in Poor Countries
However, with poorer countries, it is found to be getting much worse.
Poorer countries also deal with escalated “indoor pollution,” which is usually affected by wood smoke and wood fires, which are used for cooking and heating in low-income regions. These pollutants contribute to 1 out of every 9 deaths worldwide.
It’s important to note that we also deal with indoor air pollution, so much so that even with all of the outside air pollution, it is the indoor air pollution that is causing roughly 50% of illnesses globally. Think about all of the chemicals that are within the pain we use, on the carpet in our homes, and coatings on furniture; these may be causing more issue than we realize.
Flavia Bustreo, WHO assistant director general, said in a statement:
“Air pollution continues take a toll on the health of the most vulnerable populations—women, children and the older adults. For people to be healthy, they must breathe clean air from their first breath to their last.” 
While experts say that wealthier countries are making efforts to clean up their air, it isn’t enough. China, for example, has the 6th highest death rate linked to pollution due to its large industrial complexes.
The reports from WHO are based on sources from 2012, which are the most recent available to the public.