Air pollution knows no boundaries. The latest WHO estimates, dated May 2018, show that this is a major health problem worldwide. Air pollution is responsible for 7 million premature deaths each year. More than 9 out of 10 deaths occur in low- and middle-income countries, mainly in South-East Asia and Africa, followed by low- and middle-income countries in the Eastern Mediterranean, Europe and the Americas. . Air pollution is recognized as a critical risk factor for noncommunicable diseases (NCDs) causing stroke, heart disease, lung cancer, as well as acute and chronic respiratory diseases such as asthma.
Exposure to high levels of pollutants can result in itching eyes, nose and throat irritation, headaches, or nausea and cough. In the long run, the effects are more pernicious!
Stroke or ischemic heart disease occurs when blood flow to the brain or cardiac muscle (myocardium) is interrupted or insufficient. Air pollution, depending on the intensity of pollutant deposition in the pulmonary tree, and the toxicity of inhaled pollutants, is a triggering factor. Ultrafine particles (tobacco smoke, combustion particles, bacteria and viruses) can reach the lungs, pass through the cell membranes of the pulmonary alveoli, and enter the bloodstream. The WHO estimates that 54% of air pollution-related deaths are attributable to ischemic heart disease and stroke.
Ambient air pollution due to the use of biomass for kitchen fires or heating (wood or dung) poses a higher risk of acquiring pneumonia, especially in children. In case of pneumonia, the cells are filled with pus and liquid, which makes the breathing painful and limits the absorption of oxygen. According to the WHO, 21% of premature deaths associated with air pollution result from pneumonia.
Air pollutants can weaken the bronchi, making them more vulnerable to viruses and bacteria. It is the latter that promotes acute or chronic bronchitis, which can degenerate into chronic obstructive pulmonary disease (COPD). COPD is characterized by progressive narrowing and permanent obstruction of the airways and lungs. This is one of the possible causes of sudden death in adults. The WHO estimates that about 19% of premature deaths related to air pollution result from this factor.
The 2013 International Center for Research on Cancer (IARC) assessment found that air pollution was carcinogenic, particulate matter being the pollutant most closely associated with an increased incidence of cancer - especially lung cancer. A link has also been established between air pollution and the increase in the number of urinary tract / bladder cancers.
Air pollution aggravates pollen toxicity for two reasons.
First, the fine particles present in the polluted air exacerbate the aggressiveness of the pollen. Pollutants settle on pollens, weaken the grain surface and make them more toxic. Pollution also increases pollen production, making them more numerous, bigger and more allergenic.
In addition, the fine particles inhaled irritate the respiratory and ocular mucosa, making the airways more receptive and facilitating the accessibility of pollen in the body. The sensitivity of individuals to pollen is thus increased during pollution peaks. That's why even in cities where there is little greenery, the city population is sensitive to allergies.
Pollutants are known to impair fertility, favore premature births or intrauterine mortality. The risk of giving birth to a child of small weight is also increased. Hypertrophy has detrimental effects, causing some children to experience significant retardation of intellectual development.
Infants and young children are very vulnerable to air pollution because of their respiratory and immune systems that are still under development. A recent study, conducted in Sweden, indicates that the inhalation of particles produced by road traffic during infancy irreversibly reduces lung capacity1. The damage done to the brain is also considerable. Professor Phillippe Grandjean, a specialist in environmental medicine, does not hesitate to talk about "chemical brain drain".
Older people are particularly sensitive to air pollution because of the decrease in their local antioxidant capacity and the adaptability of their defense system. According to a study carried out in Tokyo2 hospitals, the number of senior admissions in emergency services increases significantly during pollution peaks, for a number of serious cardio-respiratory diseases (myocardial infarction, insufficiency). cardiac, asthma, bronchitis).
In low- and middle-income countries, women are heavily overexposed to air pollution because of their role in food preparation. They cook on stoves or fires that fill the room with thick smoke emitted by polluting fuels such as wood, animal excrement or charcoal. Health risks are therefore major.
People exposed continuously to certain pollutants are not spared from the ravages of air pollution: smokers, construction workers, transport trades, garages, etc.
According to the WHO, the development of asthma is linked to the association of genetic predisposition and exposure to particles in the environment. Researchers from the National Institute of the Industrial Environment and Risks (INERIS) note an increase in hospital admissions for asthma attacks during strong peaks of pollution, regardless of climatic conditions. They also emphasize the role of particles in the deep penetration of allergens.
A study in Brescia3 in northern Italy found a 3% increase in hospital admissions for an increase in PM10 concentration of 10 µg / m3 per day. Particles tend to clog the arteries and promote the risk of atherosclerosis.
1Schultz ES. et al., Traffic-related air pollution and lung function in children at 8 years of age: a birth cohort study.
2 Ye F. et al, Effects of temperature and air pollutants on cardiovascular and respiratory diseases for males and females older than 65 years of age in Tokyo
3 Nodari S. et al., Endothelial Damage Due to Air Pollution