HealthWise: Not just lungs and heart, air pollution does deeper damage

Air pollutants cause frequent lung infection, chronic obstructive lung disease, lung cancer, heart attack and stroke, but lesser known is the long-term health damage from non-cardiopulmonary diseases and infections.

One in eight deaths in India is attributable to air pollution, which accounts for at least 11% of all premature deaths in people younger than 70 years, according to the most comprehensive state-wise estimate of air pollution-related disease and deaths published in The Lancet Planetary Health in 2018.

While most people associate air toxins with lung disease, 38% of the disease burden from air pollution in India is from heart disease and diabetes, found the study, which estimated it accounted for 1·24 million or 12·5% of the annual deaths.

The study found no state in India has an annual mean fine particulate matter 2.5 (PM2.5 micrometres are particles one-400th of a millimetre) lower than the WHO recommended level of 10µg/m³, with 76.8% of India’s population was exposed to mean PM2·5 more than 40µg/m³, which is the recommended limit set by the National Ambient Air Quality Standards of India.

Universal risk

“Air pollution is now the most pervasive public health threat across all ages. From affecting the health of the unborn child through placental transfer and damaging the lungs of the young child to asthma, heart attacks, strokes, chronic obstructive lung disease, dementia and osteoporosis, the list of health disorders is growing in range of recognition by research and magnitude of documented damage. This calls for urgent and energetic multisectoral response,” said Dr K. Srinath Reddy, president, Public Health Foundation of India.

Air pollutants are associated low birth-weight, anaemia, oxidative stress and degenerative diseases such as osteoporosis, chronic kidney disease, age-related memory loss, among others. Among the lesser known extrapulmonary diseases of air pollution contributes to and exacerbated are:

Diabetes

Air pollution damages a several biological pathways associated with glucose metabolism and leads diabetes. Long-term exposure to PM10 in India led to higher glycaemia and insulin resistance and exacerbated the progression and complications of diabetes, found the Wellcome Trust Genetic Study co-authored by researchers from four institutes in Pune. “Atmospheric pollution, particularly PM2.5 and PM10, is directly related to inflammation, insulin resistance and diabetes, which has been shown in India and several countries. Of equal importance is increased progression to complications of diabetes, in particular, heart attacks in people with diabetes. It is the leading cause of death in people with diabetes,” said Dr Anoop Misra, chairman, Fortis Centre of Excellence for diabetes, metabolic diseases and endocrinology.

Exposure to PM2.5 and nitrogen dioxide (NO2) from vehicular and power plant emissions raises diabetes prevalence and levels of haemoglobin A1c (HbA1c, which is a measure of glucose control over the past three months), according to International Journal of Hygiene and Environmental Health. People with HbA1c levels between 5.7% and 6.4% have a higher chance of getting diabetes, 6.5% or higher indicate diabetes.

Anaemia

Chronic exposure to pollution raised systemic inflammation and affect red blood cells production (erythropoiesis), leading to anaemia, reported a study in the journal, Environment International. Anaemia is defined as haemoglobin count of <13 g/dL for men and <12g/dL for women, and leads to chronic fatigue, lowers immunity, impairs movement and lowers brain function. The study found that air pollution exposures were associated with a significant increase in the prevalence of anaemia and a drop haemoglobin levels in older adults in the US, where chronic ambient air pollution levels are much lower than across India.

Osteoporosis

Two independent studies have linked high PM2.5 level with the loss of bone mineral density and osteoporosis-related fractures in people 65 years old and above in the US. The first study found the risk of bone fracture hospital admissions was greater in areas with higher PM2.5 concentrations, particularly in low-income groups. The second study linked carbon concentration in the air with higher loss of bone-mineral density over time at multiple anatomical sites, including femoral neck (where the leg bone joins the hip joint) and ultradistal radius (bone in the forearm), which raises risk of hip and arm fractures.

Chronic kidney disease

High PM2.5 concentrations leads to increased chronic kidney disease (CKD) and progression to end-stage renal disease (ESRD), kidney function decline (glomerular filtration rate or eGFR decline ≥30%), and kidney failure, according to a study in the Journal of the American Society of Nephrology. The risk of CKD and its progression was most pronounced at the highest levels of fine particulate matter concentrations, found the study.

People living closer to a major road had lower eGFR than patients living farther away, found a study of living in the proximity to a busy road and kidney function in the Boston area in the US, reported a study in the Journal of Epidemiology and Community Health. People living within 50 m of a major road had 3.9 mL/min/1.73 m2 lower eGFR than those living 1,000 m away, which is comparable to what’s people who are at least four years older in population-based studies. The constellation of findings suggests that chronic exposure to PM2.5 is a adds to risk of development and progression of kidney disease.

Inflammation

Toxins in the air we breathe elevate levels of C-reactive protein (CRP), a marker of systemic inflammation associated with inflammatory conditions such as cardiopulmonary disease and several autoimmune conditions, including rheumatoid arthritis, lupus, and some inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, certain cancers like that of the lung and, possibly, colorectal, breast, and ovary. On high pollution days when PM inhalation is unavoidable, experts advise people over 65 years old and those with existing diseases minimize exposure and use anti-inflammatory treatment if exposure cannot be avoided.

“Even in places where air pollution is comparatively low in India, it exceeds national and WHO norms during seasonal peaks, leading to cumulative exposure and sustained damage to the entire population. Action must be local but policies must address the concerns of the entire population to ensure everyone gets to breathe clean air,” said Dr Reddy.