Air Pollution: Understanding The Toxic Air We Breathe

Air pollution is a major threat to global health and prosperity. It is caused by the release of pollutants into the air, which are detrimental to human health and the planet. These pollutants are a mix of hazardous substances from both human-made and natural sources. Human-made sources include vehicle emissions, fuel oils, industrial processes, and power generation, while natural sources include wildfires, dust storms, and volcanic eruptions. According to the World Health Organization (WHO), indoor and outdoor air pollution is responsible for nearly seven million deaths worldwide each year, with low- and middle-income countries suffering the highest exposures. Air pollution is a complex issue that requires interventions and initiatives to address its health risks and mitigate its impact on the environment.

Air pollution is a mix of hazardous substances from human-made and natural sources

Air pollution is a significant environmental health hazard that affects both indoor and outdoor environments. It refers to the presence of hazardous substances in the air, which can be detrimental to human health, other living beings, and the planet. These substances are released into the air from a variety of human-made and natural sources.

Human-made sources of air pollution include vehicle emissions, fuel oils, natural gas used for heating and cooking, industrial processes, power generation, and manufacturing. The burning of fossil fuels, such as coal, natural gas, oil, and gasoline, releases harmful chemicals and gases into the air. This includes ground-level ozone, carbon dioxide, carbon monoxide, nitrogen oxides, sulfur oxides, and particulate matter. Particulate matter, especially fine particulate matter (PM 2.5), is considered one of the most deadly forms of air pollution, as it can penetrate deep into the lungs and contribute to serious health problems.

Indoor air pollution is often caused by the use of biomass, such as wood, for cooking and heating, as well as the use of kerosene and coal. Gas stoves, furnaces, and other fuel-burning heating devices emit pollutants such as NO2, benzene, and carbon monoxide. Secondhand cigarette smoke is also a significant source of indoor air pollution, increasing the risk of lung cancer for those exposed.

Natural sources of air pollution include wildfires, dust storms, volcanic eruptions, and gases emitted from decomposing organic matter in soils, such as methane. While some natural sources of air pollution, such as windblown dust or sand, may not be directly caused by humans, other natural sources, such as wildfires, are often a result of human activities.

The effects of air pollution on human health are significant. Exposure to air pollution has been linked to respiratory diseases, heart disease, lung cancer, asthma, and other chronic illnesses. It is also a risk factor for early death, with an estimated 6.5 to 8 million deaths globally attributed to air pollution each year. Additionally, air pollution impacts the environment, affecting crops, forests, and contributing to climate change.

Addressing air pollution requires a combination of interventions, policies, and technological solutions. Strategies such as sustainable land use, cleaner energy sources, improved waste management, and the implementation of air quality regulations have proven effective in reducing air pollution and mitigating its health and environmental impacts.

Pollutants of major public health concern include particulate matter, carbon monoxide, and nitrogen dioxide

Air pollution is the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. Pollutants of major public health concern include particulate matter, carbon monoxide, and nitrogen dioxide.

Particulate matter, or PM, is a complex mixture of extremely small particles and liquid droplets containing acids, organic chemicals, metals, and soil or dust particles. Sources of PM are both natural and anthropogenic. Natural sources include volcanoes, fires, dust storms, and aerosolized sea salt. Manmade sources of PM include combustion in mechanical and industrial processes, vehicle emissions, and tobacco smoke. PM is categorized by size and is the fraction of air pollution most reliably associated with human disease. The World Health Organization estimates that PM contributes to approximately 800,000 premature deaths each year, making it the 13th leading cause of mortality worldwide. PM has been linked to strokes, heart disease, lung cancer, and acute and chronic respiratory diseases.

Carbon monoxide, or CO, is a colorless, odorless gas that can be harmful when inhaled in large amounts. CO is released when something is burned. The greatest sources of outdoor CO are cars, trucks, and other vehicles or machinery that burn fossil fuels. A variety of household items also release CO, including unvented kerosene and gas space heaters, leaking chimneys and furnaces, and gas stoves, which can affect indoor air quality. CO reduces the amount of oxygen that can be transported in the blood to critical organs like the heart and brain. At very high levels, CO can cause dizziness, confusion, unconsciousness, and death.

Nitrogen dioxide, or NO2, is a gaseous air pollutant composed of nitrogen and oxygen. NO2 forms when fossil fuels such as coal, oil, methane gas, or diesel are burned at high temperatures. NO2 contributes to particle pollution and the chemical reactions that make ozone. NO2 can be formed both outdoors and indoors when fuels like wood or gas are burned. While everyone is at risk from the health impacts of nitrogen dioxide pollution, those who live near emission sources are at higher risk. Other vulnerable subpopulations include people with pre-existing medical conditions such as asthma, cardiovascular disease, and diabetes, as well as people of color. NO2 causes a range of harmful effects on the lungs and has been linked to an increased likelihood of hospital admissions. Scientific evidence suggests that exposure to NO2 could cause asthma in children.

Outdoor air pollution comes from industrial processes, burning fossil fuels, waste management, and agriculture

Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. Outdoor air pollution is a major environmental health problem affecting individuals in low-, middle-, and high-income countries. In 2019, outdoor air pollution was estimated to have caused 4.2 million premature deaths worldwide.

In the context of waste management, open burning of waste and poor waste management practices contribute to outdoor air pollution. Agricultural activities, particularly intensive animal farming, also play a role in air pollution. Concentrated animal feeding operations (CAFOs), where a large number of animals are confined, generate waste (manure, urine, and byproducts) and animal husbandry-related products (feed, pesticides, antibiotics, and hormones) that contribute to hazardous emissions, including air pollutants and malodorous compounds.

To address outdoor air pollution, concerted action is required from policymakers and individuals. Successful policies that reduce air pollution include implementing clean technologies in industries, improving waste management practices, transitioning to cleaner energy sources and fuels, promoting sustainable land use, and improving energy efficiency in buildings. Individual actions, such as shifting to cleaner modes of transportation and reducing personal energy consumption, can also contribute to mitigating outdoor air pollution.

Indoor air pollution is caused by the use of biomass (e.g. wood) for cooking and heating

Air pollution is a mix of hazardous substances from both human-made and natural sources. It is a familiar environmental health hazard, and a major threat to global health and prosperity. According to the World Health Organization (WHO), air pollution, in all forms, is responsible for about seven million deaths each year globally.

Indoor air pollution is a significant contributor to this figure. Around 2.1 billion people worldwide, roughly a third of the global population, cook using open fires or inefficient stoves fuelled by biomass (wood, animal dung, crop waste, charcoal, coal, etc.) and kerosene. This generates harmful household air pollution. The combustion efficiency of biomass is very low, yielding high levels of products of incomplete combustion, which are more damaging to health. The adverse health effects of indoor air pollution are often exacerbated by a lack of ventilation and the poor design of stoves that do not have flues or hoods to take smoke out of the living area.

Household air pollution was responsible for an estimated 3.2 million deaths per year in 2020, including over 237,000 children under the age of five. The combined effects of ambient air pollution and household air pollution are associated with 6.7 million premature deaths annually. Household air pollution exposure leads to non-communicable diseases including stroke, ischaemic heart disease, chronic obstructive pulmonary disease (COPD), lung cancer, and respiratory infections such as pneumonia, tuberculosis, and low birth weight. Women and children, who are typically responsible for household chores such as cooking and collecting firewood, bear the greatest health burden from the use of polluting fuels and technologies in homes.

The Global Alliance for Clean Cookstoves is an initiative by the United Nations to improve the lives of people dependent on biomass fuel. WHO has also issued a set of normative guidance, the Guidelines for Indoor Air Quality: Household Fuel Combustion, which offers practical evidence-based guidance on what fuels and technologies used in the home can be considered clean.

Air pollution is associated with respiratory issues, oxidative stress, inflammation, and an increased risk of chronic diseases and cancer

Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. Common sources of air pollution include household combustion devices, motor vehicles, industrial facilities, and forest fires.

Air pollution is a major public health concern, contributing to a range of respiratory issues and other health problems. One of the key ways air pollution damages health is through oxidative stress. Particulate matter with an aerodynamic diameter of ≤2.5 μm, originating primarily from combustion processes, is considered the most toxic. This particulate matter contains peroxides and reactive oxygen species (ROS), which are crucial mediators of particle toxicity and can cause oxidative stress in the body.

In addition to respiratory issues, air pollution is associated with inflammation. When particles of pollution enter the body, the innate immune response is activated, leading to the production of cytokines and other inflammatory molecules. These molecules can also enter the bloodstream and have toxic effects. Particulates from fires, for example, can lodge themselves in the lungs, causing chronic inflammation. Studies have found higher levels of inflammatory molecules in the blood of people with long-term exposure to air pollution.

Air pollution is also linked to an increased risk of chronic diseases and cancer. Long-term exposure to fine particles in the air has been associated with a decrease in lung function growth in children and increased respiratory symptoms, such as asthma. Additionally, air pollution is a contributing factor to lung cancer, with studies showing that changes in airway cells due to particle pollution are visible in about half of people with lung cancer who have never smoked. Air pollution is estimated to cause millions of premature deaths annually, with low- and middle-income countries bearing the heaviest burden.

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