According to the latest guidelines from the World Health Organization (WHO), the annual average outdoor concentration standard for fine particulate pollutants (PM2.5) has been lowered to 5 micrograms per cubic meter from the previous standard of 10 micrograms per cubic meter.
Numerous studies have been conducted to show that long-term exposure to high PM2.5 concentrations can increase the risk of premature death.
A recent study published in Science Advances suggests that low concentrations of PM2.5 can increase the risk of premature death, even when air quality standards are met.
The researchers tallied data on 7 million Canadian deaths over 25 years with outdoor PM2.5 concentrations in Canada to precisely characterize the response of air pollutant concentrations to non-accidental mortality, and extended the results to a global scale.
The results show that average annual exposure to lower PM2.5 pollution levels (2.5 to 5 micrograms per cubic meter) also leads to at least 1.5 million premature deaths globally.
For comparison, the World Health Organization estimated in 2016 that 4.6 million people die prematurely each year due to chronic exposure to high levels of outdoor PM2.5.