This claim is true, and here are a few reasons as to why it holds truth. According to CNBC, air pollution actually takes an average of 2.2 years off the global life expectancy average, which its information was taken from the Energy Policy Institute at the University of Chicago. Furthermore, the Air Quality Life Index found that air pollution takes a total of 17 billion years of life, but by reducing it, an additional 2.2 years could be added to the life expectancy (so 72 to 74.2 years).
Another news site, The Wall Street Journal, stated that air pollution is the world's top threat to the United States public health, and it shortens human lifespans more than even the product of tobacco.
Lastly, the problem of air pollution is not only one here but in other areas beyond the United States. According to Aljazeera, the life expectancy in South Asia was cut by 5 years due to heavily air polluted countries, such as India, Bangladesh, Nepal, and Pakistan. Pollution levels are now 50% higher than they were at the start of the century.