Air pollution drop leads to reduction in suicides: study

By Isobel Williams via SWNS

Air pollution may be linked to suicide as cutting emissions led to a drop in people taking their own lives, according to a new study.

American scientists found that China's suicide rate fell by 46,000 over five years following efforts to reduce air pollution.

Issues like air pollution are often framed as a physical health problem leading to a spectrum of acute and chronic illnesses such as asthma, cardiovascular disease and lung cancer.

Now, a new study from the University of California has suggested that these environmental factors can take a toll on mental health as well.

The researchers were inspired to conduct their study, published in the journal Nature Sustainability, when they saw that the suicide rate in China was dropping much faster than the rest of the world.

In 2000, the country’s per-capita suicide rate was higher than the global average, and two decades later it has fallen below that average.

With air pollution levels also plummeting, the team decided to investigate if there was a link.

Assistant Professor Tamma Carleton from UC Santa Barbara’s Bren School of Environmental Science & Management said: “It’s very clear that the war on pollution in the last seven to eight years has led to unprecedented declines in pollution at a speed that we really haven’t seen anywhere else.

“Thirty years of warming in India led to about the same magnitude of suicide effects as about five years of air pollution control in China.”

They gathered demographic data from 2013 through 2017 from the Chinese Center for Disease Control and Prevention and meteorological data from the China Meteorological Data Service Center.

To isolate the effects of air pollution the researchers took advantage of an atmospheric condition called an inversion, where warm air traps a layer of cold air beneath it like a lid on a pot.

This can concentrate air pollution near the surface, leading to days with higher pollution levels that aren’t correlated with human activity.

Dr. Carleton said: “One of the bigger challenges with prior work on this problem is that air pollution is correlated with a lot of things.

“Our goal was to isolate just the role of pollution on suicide as opposed to all the other things that might be correlated with air pollution.”

They then compared suicide numbers across 600 counties between weeks with inversions and those with more typical weather, running the data through a statistical model.

The authors found that suicide rates increase substantially when air pollution rises.

This effect was particularly strong for elderly people, with older women 2.5 times more vulnerable than other groups.

They also discovered that this phenomenon happens quickly, with rates increasing in the first week of exposure and abruptly declining once conditions improve.

The team say this suggests that pollution may have a direct neurologic effect, rather than creating chronic health issues that drive suicide rates up later on.

The researchers hope that their findings will encourage society to change the way that they think about suicide prevention.

Dr. Carleton added: “We often think about suicide and mental health as a problem to be understood and solved at an individual level.

“This result points to the important role of public policy, of environmental policy, in mitigating mental health and suicide crises outside of individual-level intervention.

“Public policy about air pollution — something you can’t control, what’s outside your window — is affecting the likelihood that you take your own life. And I think that puts a different lens on the solutions we should be thinking about.

“It’s important that public health officials also know this as our climate gets warmer, and as pollution increases in many developing countries.”

Dr. Carleton hopes to further study suicide rates in the future, noting that pollution is not the only factor that can lead a person to end their life.

She concluded: “About 10 percent of the overall decline over these past five years can be attributed to particulate pollution. That’s important, but it also leaves 90 percent unexplained by pollution.”