According to the State of Global Air, this statement is true. According to the article, in 2019, "air pollution shortened life expectancy by 1 year and 8 months".
This statement is based off of research done during this year. However, areas with less development will have a larger affect.
According to the article, air pollution "life expectancy losses were greatest in Oceania, South Asia, and sub-Saharan Africa". These losses can get up to almost 3 years life expectancy loss.