Half of the World's Population will be Exposed to Frequent Still Air Events by End of 21st Century

Climate change might worsen air pollution, researchers at Stanford said. The team estimates that by the end of this century around 55 percent of the world's population will witness frequent air stagnation events.

Climate models show that rising air pollution could lead to an increase in days when air with high levels of particle pollution lingers over cities. Poor quality air could lead to cardiovascular and respiratory illnesses.

According to scientists at the Stanford University, air stagnation is the condition under which pollutants can accumulate in the atmosphere.

"Air stagnation by itself is not necessarily a bad thing for public health, for us," said Daniel Horton, a research fellow in earth system science at the Stanford University in California and the study's lead author, according to nbcnews.com. "You still need the pollutant component in there."

Those components are fine particles that can lodge in lungs and lead to several health problems.

Researchers used data from the National Climatic Data Center's air stagnation index and applied it to collection of global climate models. These models simulate earth's climate and environmental conditions in the present century.

A day with stagnant air is when there is no rain, light winds near the surface and lighter winds in the atmosphere. The three conditions together create a system where the polluted air has nowhere to go and lingers in a given area.

"All three conditions have to occur simultaneously," Horton said in a news release. "If it doesn't rain on a particular day, but the winds are very strong, a stagnation event is not likely to occur."

Researchers found that by the end of this century, areas covering about 55 percent of the Earth's population will experience frequent air stagnation. Some of these areas can see over 40 stagnation days per year. Researchers said that countries such as India, China, Mexico and parts of the United States are at an increased risk of suffering from frequent air stagnation.

The team also said that climate change will lead to longer periods of air stagnation, affecting millions of people around the world.

The study is published in the journal Nature Climate Change.