That air pollution is extremely harmful to health is a well-known fact. Now, a new study has also established a link between air pollution and the heightened risk of stroke and subsequent death. The research from Sun Yat-sen University School of Public Health in Guangzhou, China, published in Neurology, focused on the negative health impacts of PM 2.5 granules, the fine particulate matter (PM) that has a diameter of fewer than 2.5 microns (about 30 times smaller than a single human hair).
The research also included a study of nitrogen dioxide (NO2) and nitrogen oxides (NO) levels in polluted air and measured air pollutant levels by their weight in micrograms — 1-millionth of a gram — per 1 cubic meter of air, expressed as µg/m3.
According to the observational study based on an analysis of the health records of 3,18,752 people in the UKBiobank and several years of UKBiobank air pollution data, for every PM 2.5 increase of 5 µg/m3, the risk of a first stroke rose by 24 per cent, and the risk of a first fatal stroke increased by 30 per cent. The research identified 5,967 incident stroke patients, 2,985 post-stroke cardiovascular patients, and 1,020 deaths afterward.
The risk of cardiovascular mortality for people who have already had a stroke also saw a “slight increase”. This was especially true of NO2, which increased mortality risk by 0.04 per cent, although this effect tapered off with time, noted the study.
Dr Amit Shrivastava, senior Consultant – Neurology, Dharamshila Narayana Superspeciality Hospital said that increase in air pollution is considered to account for 14 per cent of all stroke-related fatalities, according to the Journal of the American Heart Association. “Air pollution can also damage children’s cognitive abilities, increase the likelihood of a cognitive decline in adults, and even lead to depression,” he told indianexpress.com.
Short-term exposure to air pollutants is closely related to COPD (Chronic Obstructive Pulmonary Disease), cough, shortness of breath, wheezing, asthma, respiratory disease, and high rates of hospitalisation (a measurement of morbidity), according to a review published in Frontiers in Public Health, whereas the long-term effects associated with air pollution are chronic asthma, pulmonary insufficiency, cardiovascular diseases, and cardiovascular mortality. The review, too, suggested that short term exposure to air pollution was related to stroke among others.
Stressing that stroke is the main reason for disability and the second largest cause of death in the world, Dr Sameer Arora, senior consultant, neurology, Narayana Hospital Gurugram said that high levels of air pollution are linked to an increased risk of transitioning from being healthy to having a stroke.
“Nitrogen oxide and nitrogen dioxide have been linked to an increased risk of stroke and mortality. Pollution is a major source of worry for public health, and it is regarded as one of the leading causes of mortality and disease. The danger posed by air pollution is determined by both the length of exposure and the toxicity of the pollutant,” Dr Arora told indianexpress.com.