Air pollution is a major driver of global death, contributing to about 11.65% of deaths. It is one of the leading causes of death in middle- and low-income countries.
Studies by the World Health Organisation (WHO) and Institute of Health Metrics Evaluation, IHME’s Global Burden of Disease have estimated annual global death tolls, resulting from the negative health effects of air pollution, to be approximately 7 million and 6.7 million respectively.
Air pollution and its associated health disorders such as cancers, cardiovascular disorders, and respiratory diseases, not only cause death but also reduce the quality of life, thus negatively impacting life expectancy.
The air we breathe gets polluted by particulate matter (PM) from different sources. The smaller the size of the particulate matter, the more damaging it is to both humans and animals. Fine and ultrafine particles such as PM2.5 are associated with more serious health disorders, as they have easier access to the deepest part of the respiratory system and blood.
Other air pollutants include ground-level ozone, sulphur oxides, nitrogen oxides, carbon monoxide, and lead.
Extreme levels of air pollution have been reported in countries such as India, China, Mexico, Brazil, Nigeria, Japan, and Russia.
Air pollution is broadly categorised into indoor and outdoor pollution. Whilst 4.1% of global mortality is attributed to indoor air pollution, a larger rate of 7.8% is caused by outdoor air pollution.
Indoor or household pollution is a worrisome health risk factor in countries in sub-Saharan Africa, Asia, and Latin America, which show heavy dependence on unclean cooking fuels, such as dung, coal, charcoal, and wood, among others.
Burning these fuels within enclosed spaces generates particulate matter, which is a principal source of indoor pollution, and poses a major respiratory threat to human subjects. However, with the increase in the availability of clean cooking fuel and advances in technology, the death rate associated with indoor pollution sources has decreased over the years.
On the other hand, outdoor pollution, whether naturally or anthropogenically driven, is a primary public health hazard closely related to the increasing levels of global urbanisation and industrialisation. Hence, there is an increased generation of greenhouse gases accompanied by climate change and health disorders.
Although outdoor air pollutants are mainly particulate matter and “tropospheric or ground-level ozone”, lower death rates have been associated with the latter. Anthropogenic sources of the aforementioned pollutants include emissions from motor vehicles, cigarette smoke, manufacturing and industrial plants such as coal power plants and production factories, burning of fossil fuels, and agricultural activities.
Dust storms, volcano ashes and gases, decomposition gases such as methane, and forest fires constitute natural sources of outdoor air pollutants.
Exposure to air pollutants has been associated with a wide range of health disorders, especially in susceptible individuals. Depending on the environment, inhalation dose, and individual susceptibility, observed effects of air pollution range from temporary respiratory disorders such as cough, wheezing, irritations of the nose, eyes, and throat, breathing difficulties, allergies, headaches, nausea, dizziness, to serious disorders such as asthma, pneumonia, Chronic Obstructive Pulmonary Disease (COPD), lung-heart disorders, cancers, diabetes, stroke, neurological, cardiovascular and reproductive diseases.
Additionally, infant mortality and chronic health disorders in adult age have been linked to air pollution-related fetal cardiovascular, respiratory, neurological, and perinatal disorders. Furthermore, with the increase in exposure to air pollutants, there is increased disease transmission, immune system destabilisation, and hospitalisation rates resulting from morbidity.
Air pollution has impacted environmental health as well. Toxic amounts of sulphuric and nitric acids in acid rain, fog, snow, or dry precipitation cause water and soil acidification, harming plants and aquatic life. Buildings, infrastructures, sculptures, and monuments are damaged.
Reproductive and other health disorders have been reported in wild animals as well. Eutrophication of the aquatic environment causes death and destabilises the biodiversity of aquatic species.
Vehicular and industrial emissions produce haze and smog which block solar radiation and reduce visibility and affect photosynthesis. Furthermore, the depletion of the stratospheric ozone layer by hydrocarbons exposes the earth to harmful UV irradiation which interferes with plant metabolic processes.
Ultimately, the increasing accumulation of large amounts of greenhouse gases in the Earth’s atmosphere and the attendant global warming and climate have adverse effects on human and human existence. Increases in regional temperature pose health risks such as heat stroke to people living in these areas.
The climatic disruptions disturb agricultural and food production processes. Snow caps and glaciers melt. Whilst droughts are reported in some regions (Somalia, and Ethiopia), sea levels increase in others such as (Nigeria, the Philippines, and Bangladesh) causing floods, submergence of cities, and displacements of human and animal settlers.
Air pollution is a health emergency that needs immediate mitigation measures as it affects all aspects of life. Anthropogenic activities are major sources of air pollutants, therefore collaborative strategies involving governments, health workers, scientists, and media entities are needed to educate the public and combat air pollution and its resultant adverse effects.
By Nwamaka Uzonnah