How air toxins hurt insidiously
By: Ms. Sanchita Sharma*
Have you been feeling tired lately? Or irritable? Listless? It’s the toxic air you’re inhaling. It makes you feel sick and depressed. Air pollution, mostly caused by transport, power generation, industrial or agricultural emissions and heating and cooking at home, raises risks for several illnesses, such as asthma, heart attack and stroke. But it also hurts you in far more insidious way.
Air pollutants contain suspended chemicals, toxins and metals that penetrate into lungs and the brain, affecting mood and memory. Outdoor air pollution increases symptoms of depression, making people feel dissatisfied, worthless, bored, unhappy and hopeless, reports a study in the journal Environmental Health Perspectives. People who lived in neighbourhoods with high ambient levels of suspended dust and carbon particles (suspended particulate matter, or SPM10), nitrogen dioxide and ozone had disturbed sleep and were more prone to alcohol and substance abuse, the study found.
Then there’s the indirect link to mood degeneration. Studies have linked air pollution to an increased risk of heart attacks, strokes and chronic lung disorders, which are associated with dementia and poor brain health.
Suspended particulate matter (PM10 and PM2.5) and ozone raise the risk of Alzheimer’s disease and dementia, reports the Journal of Alzheimer’s Disease. The study, of close to 100,000 people, showed that even short-term exposure to particle pollution more than doubles the risk of developing Alzheimer’s. Another study of close to 20,000 women living across the US published in the Archives of Internal Medicine showed that over time, breathing in polluted air speeds up brain decline and contributes to the equivalent of about a two-year decline in brain function. Air toxins are particularly damaging for young minds. They lower brain development in 7 to 10-year-old children. Children from schools in polluted neighbourhoods did worse in tests of working memory, superior working memory, and attentiveness, showed the year-long study of 2,715 primary school children across 39 schools in Barcelona, Spain.
Chronic exposure to pollution warps the immune system and makes it mistake airborne particles for hostile pathogens, such as virus or bacteria, and launch an attack to seek and destroy them. Fine carbon and dust particles (PM2.5) cause low-level inflammation that disrupts the body’s immune response at several levels. A study in the Archives of Environmental and Occupational Health found that women exposed to outdoor pollution tested high for inflammation markers (C-reactive protein, serum amyloid A, interleukin-6) and functional tests of cellular immunity (natural killer cell cytotoxicity, T-lymphocyte proliferation). This constant state of pressure overworks the immune system and makes it too weak to fight infection when it really occurs, report researchers in Circulation Research.
Polluted air causes cancer, said the France-based International Agency for Research on Cancer, after reviewing scientific data that established outdoor air pollution caused 2.23 lakh lung-cancer deaths worldwide in 2012. This puts it at the same toxic level as tobacco, alcohol, ultraviolet radiation. Air pollution also increases the risk of bladder cancer. Particulate matter, a major component of air pollution, was classified as carcinogenic.
Animal models show pollution lowers good bacteria and increase the bad ones in the gut, impairing liver function, causing intestinal swelling, and altering fat and glucose metabolism, leading to diseases such as the gastroenteritis, irritable bowel syndrome and early-onset Crohn disease, shows research in the journal Gut Microbes.
The new study from Beijing in rats, which was published in The FASEB Journal, found pregnant rats exposed to Beijing’s polluted air are significantly fatter at the end of pregnancy than those exposed to filtered air. Their offspring exposed to unfiltered air in the womb and after birth were also heavier than those who inhaled clean air. In both continuous exposure to unfiltered air caused airway inflammation in the lungs, increased tissue and systemic oxidative stress, dyslipidemia (abnormalities in cholesterol and other blood fats), and changes in fat distribution, leading to belly fat that raises risk of diabetes and heart disease. With exposure to pollution being among the highest in India and China, with large populations going through rapid industrialization, controlling it using policy, regulation and technology is the only way to lower disease and death.
*Health & Science Editor, Hindustan Times, New Delhi, India <[email protected]>