(CNN)More than 95% of the world's population is breathing unhealthy air and the poorest nations are the hardest hit, a new report has found.
According to the annual State of Global Air Report, published Tuesday by the Health Effects Institute (HEI), long-term exposure to air pollution contributed to an estimated 6.1 million deaths across the globe in 2016.
The report says exposure to air pollution led to strokes, heart attacks, lung cancer and chronic lung disease, causing many of those premature deaths.
It also says that air pollution is the fourth-highest cause of death among all health risks globally, coming in below high blood pressure, diet and smoking.
"Air pollution takes a huge personal toll worldwide, making it difficult to breathe for those with respiratory disease, sending the young and old to hospital, missing school and work, and contributing to early death," Bob O'Keefe, vice president of HEI, said in a statement.
"The trends we report show real progress in some parts of the world -- but serious challenges remain to eliminate this avoidable affliction," he added.
According to the report, China and India were found to be jointly responsible for over 50% of global deaths attributable to pollution.
It also found that India now rivals China for early deaths from outdoor air pollution with 1.1 million being recorded in 2016.
While the report found that China had made some progress in declining air pollution, it states that Pakistan, Bangladesh and India have experienced the steepest increases in air pollution levels since 2010.
The report also took into account those exposed to the burning of solid fuels in their homes,