Interview/ Saurabh Mehrotra, associate director, neurology and neurosciences, Medanta, Gurugram
Given that mental health is a continuum, how do you isolate pollution as a contributor to mental health challenges?
The World Health Organization has ranked air pollution as one of the major environmental health risks accounting for about 4.2 million premature deaths. The WHO guidelines implicate PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide and carbon monoxide in poor air quality. The strongest evidence for adverse health is for PM2.5. These particles can reach the deepest parts of the lung, causing local and systemic inflammation and oxidative stress. They also find their way to the brain. All these are ultimately responsible for effects on physical and mental health.
What are the most common manifestations of mental health challenges caused by pollution?
Most of the world population breathes unsafe air. In our experience, we have seen how smog makes us feel depressed, anxious and irritable. This, although a superficial association, still conveys a point.
From research, there is emerging evidence that exposure to outdoor and indoor air pollutants may affect mental health and lead to neurocognitive disorders such as dementia. Outdoor air pollutants are risk factors for depression, anxiety, personality disorders and schizophrenia. Furthermore, there may be problems in concentration and cognitive function.
Indoor air pollution is also of great significance, since almost 90 per cent of our time is spent indoors, at work and home. Poor indoor environment may lead to fatigue and sick building syndrome, which comprises a host of physical and psychological symptoms. It also reduces work efficiency and leads to absenteeism. There are reports of brain fog, anxiety and depression related to indoor pollution. It must be emphasised that the findings are preliminary and future research will provide more information including causal mechanisms.
What about the effects of air pollution on pregnancy and newborns?
The effects of air pollution during pregnancy and on newborns are still being studied. Children exposed to poor indoor air quality in schools perform worse on math and reading comprehension tests. It is important to understand that half of adults with mental illness show symptoms by 11 years of age and 75 per cent do so by 24 years. Research suggests that psychotic experiences were more common among adolescents with the highest level of annual exposure to nitrogen dioxide and PM2.5. There is also evidence of association with depression. Reviews show an association of exposure to PM2.5 and PM10 to depression, anxiety, bipolar disorder, psychosis and suicide in adults.
What is the wider issue of air pollution and its impact on mental health that we must be addressing?
The bigger topic of climate change and mental health needs to be addressed. Extreme weather events are becoming common and faced by all of us. This is leading to job loss, forcing migration, harming social cohesion, depleting resources, and having serious mental health consequences. A new vocabulary has developed to describe such effects. Ecological grief and eco-anxiety are terms describing the sense of loss or anxiety people feel related to climate change.
Solastalgia is a term coined to capture the nostalgia we can feel for a traditional way of life or childhood landscape destroyed by environmental change. People also describe emotional burnout and despair when we fail to make progress in improving such issues.
The effects on mental health are a consequence of being in a situation like this, as well as the deeper effects on the brain because of the pollutants or toxins or stress.