Reducing Air Pollution Exposure May Lower Overall Premature, Natural Deaths

According to new data, lowering air pollution concentrations below World Health Organization (WHO) guidelines can lead to a considerable reduction of premature deaths.

Currently, air pollution is considered a major environmental cause of global morbidity and death.

“Long-term exposure to ambient particulate matter (PM) with diameter less than or equal to 2·5 μm (PM_2·5) was estimated to cause between 4 and 9 million premature deaths in 2015 globally, ranking PM_2·5 as the fifth greatest risk factor for global mortality in the Global Burden of Disease, Injuries, and Risk Factors Study (GBD) 2015,” wrote the study investigators.

The team, led by Sasha Khomenko, Institute for Global Health, Barcelona, Spain, conducted a quantitative health impact study that evaluated health effects of air pollution across 969 cities and 47 greater cities in Europe.

Looking at the year 2015, they estimated the effect of air pollution exposure on natural-cause death in adult residents aged ≥20 years.

Assessing Air Pollution and Mortality

In conducting their analysis, Khomenko and colleagues used the Urban Audit 2018 dataset to retrieve data on all cities and greater cities. Analysis was done on at a 250 m grid cell level and based on the global human settlement layer residential population.

The team then estimated the annual premature mortality burden that could be prevented if WHO recommended values (10 μg/m³ for PM_2·5 and 40 μg/m³ for NO₂) were achieved.

Similarly, they estimated burden if air pollution concentrations were reduced to the lowest values measured in 2015 in European cities (3·7 μg/m³ for PM_2·5 and 3·5 μg/m³ for NO₂).

In their findings, they noted that compliance with WHO air pollution guidelines could prevent 51,213 (95% CI, 34,036–68,682) deaths per year for PM_2·5 exposure and 900 (95% CI, 0–2476) deaths per year for NO₂ exposure.

Furthermore, they reported that the reduction of air pollution to the lowest measured concentrations could prevent 124,729 (95% CI, 83,332–166,535) deaths per year for PM_2·5 exposure and 79,435 (95% CI, 0–215,165) deaths per year for NO₂ exposure.

Nonetheless, there was a great variability in these findings among cities—which ranged from 0-202 deaths per 100,000 population for PM_2·5 and from 0-73 deaths for NO₂ per 100,000 population for the lowest measured concentrations.

The investigators estimated that the highest PM_2·5 mortality burden was for cities in the Po Valley, Poland, and Czech Republic. The highest NO₂ burden was estimated for large and capital cities in western and southern Europe.

Study Implications

This was the first known study to estimate local mortality burden due to air pollution for a large range of European cities.

“Research supports the association between air pollution and mortality at concentrations below WHO recommendations with no evidence of a safe exposure threshold,” Khomenko and team wrote.

They acknowledged that variability of mortality burden by cities may indicate where policy actions are more urgently needed so that governments can help communities achieve sustainability and livability.

Furthermore, they recommended that current guidelines should be revised. Cities should also move to lower air pollution concentrations under these guidelines.

Nevertheless, they addressed the potential future directions for their research, which includes investigating at the city level to estimate the effects of other environmental and lifestyle exposure on individuals (i.e., air pollution, noise, shortage of green spaces, heat, and sedentary behavior).

The study, “Premature mortality due to air pollution in European cities: a health impact assessment,” was published online in The Lancet Planetary Health.