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Air pollution, what it is, and how it affects our lives explored below:

Mobility and Air Pollution

Local and global movement has come to underpin our social and economic existence; it is the means to access jobs, healthcare, education, and community. It enables the financial efficiency of distributed supply chains, and shapes the geography of economies and opportunities. Yet, all of this comes at a cost. The transport sector is a major contributor to air pollution and global greenhouse gas emissions. According to the European Environment Agency, the sector contributes more than half of the region’s nitrogen dioxide and nitric oxide emissions (road transport accounted for much of this impact).


The solution can be boiled down to this: move less and electrify more. We move around - a lot. The COVID-19 crisis may have forced us to pause, but prior to that we flew an estimated 8.3 trillion passenger-kilometres in 2018 alone, according to the International Air Transport Association. In 2015, according to estimates, we shipped goods 108 trillion tone-kilometres by sea, road, rail, and waterway.

 The contribution varies - though emissions from freight and other heavy-duty vehicles typically account for a disproportionate amount of transport emissions, relative to their representation in the overall vehicle fleet. These emissions can be better controlled by improving engines, shifting to cleaner fuels, and using technologies that filter gases and particles.

The International Maritime Organization’s rules on emission controls and Sulphur content in shipping fuel are expected to reduce ship emissions that contribute to acid rain and particulate matter by 77%. Such measures must be backed up by systemic investments in refinery capacity for cleaner fuels, and by making cleaner engines affordable in low- and middle-income countries.


Other levers to pull in order to reduce air pollution include alternate modes of transport. And in cities, strategic land-use planning and zoning can maximize density and accessibility. The global trade in used cars with polluting engines accumulates in these countries, and is a growing contributor to air pollution in Africa in particular.


Ideally, it will mean better promoting public transportation and electric vehicles at a local level, and reinvigorating lower-emitting rail and shipping systems in order to replace road freight. Just about everywhere, this will mean thinking about the proper economic incentives. For industry in particular it will also mean rethinking supply chains, and the balance between digital and physical movement.

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The composition of that air is important - indoor and outdoor particulate matter (generally caused by combustion), and ground-level ozone (a gas that forms from emissions) contributed to 5 million premature deaths in 2017, according to the Institute for Health Metrics and Evaluation’s Global Burden of Disease project. Air pollution kills more people than AIDS, tuberculosis, and malaria combined. The average adult inhales 11,000 litres of air per day.


The World Health Organization has estimated that 7 million people died prematurely due to pollution exposure in 2016; a more recent analysis by the chief of the Department of Cardiology at the University Medical Center of Mainz (Germany) and other researchers pointed to even higher fatality rates. Air pollution is not only the top environmental risk factor for premature mortality - it affects the quality of life, particularly for the elderly, children, and those with pre-existing respiratory illnesses.


Even brief exposure to the sort of particulate-matter pollution generated by wildfires can cause life-long damage to lung functions. Air pollution has been shown to affect male fertility, fetal development, and cognitive functioning (including short-term fuzziness and mood swings and longer-term increased risk of dementia). In addition, hazardous chemicals emitted from waste burning and fossil-fuel refining elevate the risk of cancer.

In wealthier countries, low-income communities are more likely to be exposed to unhealthy air than higher-income groups. Air pollution also affects health indirectly - emerging epidemiological evidence suggests that it can increase susceptibility to respiratory infections, and weaken the immune response to other infectious diseases. Some of the chemicals creating air pollution - mercury from coal plants, or dioxins from waste burning, for example - also land in soil and water, ultimately making their way into the food chain and contributing to cancer, endocrine disruption, and other disorders.    


The global health impacts of air pollution are unevenly distributed. According to a WHO analysis, 91% of the premature deaths associated with outdoor air pollution occur in low- and middle-income countries, as do nearly all of the deaths associated with indoor particulate matter pollution caused by using solid fuels for cooking and heating (such as coal and wood). Indoor air pollution from cooking and heating disproportionately affects women and children.


Ozone, Sulphur dioxide, and nitrogen oxides in the air also damage plants and forests, affecting biodiversity, crop yields, nutritional value, and other critical elements of maintaining human health.

Air Quality and Health

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Air Quality and Climate Change

Cleaning the air is an important form of climate action. Air pollution shapes the pace, extent, and regional distribution of climate change. Some of its components - black carbon (darker particulate matter), ground-level ozone, and ozone precursor methane - are powerful warming agents.


According to the Climate and Clean Air Coalition, these three components alone are responsible for up to 45% of all global warming to date. Black carbon deposits on glaciers, and accelerates warming and melting in the Arctic, while regional concentrations heat the atmosphere unevenly and trigger shifts in wind patterns as well as so-called “heat islands” that plague many urban areas.

The good news is that warming pollutants have relatively short lifetimes in the atmosphere compared with carbon dioxide. Reducing emissions can translate relatively quickly into lower pollution concentrations and generate climate, health, and environmental benefits. For example, fast action on so-called “super-pollutants” and the hydrofluorocarbons used in refrigeration could stave off more than half a degree (celsius) of warming by 2050 - as well as half of the predicted warming in the Arctic, thereby avoiding tipping points such as an irreversible release of carbon dioxide and methane from melting Arctic permafrost.

Harnessing this property to slow warming has been proposed, but comes with significant uncertainty and potentially-damaging side effects (the dimming it creates reduces solar radiation available for crops and renewable energy production, for example). Some pollutants, such as sulphates and other lighter-colored particulate matter, can have a temporary cooling effect by blocking solar radiation. Particulate matter may also alter cloud formation and precipitation patterns in unpredictable ways. Climate change influences air quality through higher temperatures that drive chemical reactions faster, changes in meteorology, increased emissions including from trees, and more frequent wildfires.


Most action that is taken to reduce greenhouse gas emissions therefore also decreases air pollution. While these changes vary based on pollutant and world region, climate change is ultimately expected to make air quality worse in most polluted regions - generating associated impacts on health, and making air quality management more challenging. The main source of air pollutant emissions - fossil fuel combustion - is also the main source of greenhouse gases. The health benefits of such action have been shown to be comparable to, or exceed, the cost of greenhouse gas reductions in some parts of the world.

Air Pollution in Cities


Cities must lead the way on improving air quality, but cannot do it by themselves. Cities are already home to well over half of the world’s population, and are expected to draw roughly 2.5 billion more people by 2050. They are also hotspots for air pollution.


Urban areas have a high concentration of emission sources: vehicles, buildings, industrial activity, waste, and wastewater, not to mention large numbers of people cooking, heating, lighting, and cleaning. Even the trees in cities sometimes pollute; while they may provide cooling and control stormwater, on warmer days their leaves release volatile organic chemicals that contribute to ozone formation.

The inevitable interaction of urban emissions with pollution from agriculture, forest fires, crop burning, and power plants in neighbouring areas only aggravates matters. However, cities are also well-positioned to lead the charge against air pollution, both for themselves and for those sharing their air. They are hubs of technology and governance innovation aimed at identifying new ways to cook, heat, light, move, and produce with lower emissions, for example. They also have the density necessary to enable lower-emission transportation options and, through some shifts in planning and land use, reduce the need to travel by anything other than foot or pedal power.

Cities are also home to heavy consumption, granting them a market power that could be used to promote lower-emission electricity, water and wastewater systems, and manufactured goods. They are often politically influential, given their significant populations and economic contributions. Yet, cities need help.

Broader regulatory coordination is important - as efforts to regulate industrial or point-source pollution may motivate polluters to move to other, more permissive jurisdictions that do not have the same sort of standards in place. Mayors and other urban leaders may be under pressure to produce cleaner air, but they lack many of the policy tools required to do so effectively.


They can reroute or discourage the use of cars, for example, but meaningful shifts to cleaner fuels or tighter emissions standards are typically the result of national policy. They can also promote cleaner public transportation by better ensuring last-mile safety and connectivity, though investing in fleet conversion or other major infrastructure projects often requires transfers or approvals from other levels of government.


 In addition, cities can design a built environment or set zoning restrictions that essentially redistribute ambient pollution, though reducing emissions at their source may require action and investment outside of city limits.

Agriculture and Air Quality

Transitioning Energy for Air Quality


Hundreds of millions of tons of crops are lost every year to air pollution. Food security and cleaner air go hand in hand. Ozone damages plant cells and handicaps photosynthesis, while particulate matter and haze reduce the amount of sunlight that can reach plants. Acid rain, a by-product of sulphur dioxide and nitrogen oxide pollution, damages leaves and reduces soil quality.


According to the Climate & Clean Air Coalition, agriculture and forestry are responsible for about 40% of global black carbon and human-caused methane emissions. The global gap between yield potential and actual average yield due to ozone has been estimated to be 12% for soybeans, 7% for wheat, and over 4% for rice. A total of 250 million tons of crops were lost to ozone at levels hit between 2010 and 2012, and global ozone levels continue to rise.


While total wheat losses are highest in the Americas, rice losses are highest in Asia; maize losses extend globally. Some varieties of staple crops are more sensitive than others, and the effects of ozone have extended beyond these commodities to reduce yields of more specialized crops - from guavas to beans. While agriculture suffers from air pollution, it also contributes to the problem.


The use of crop burning and forest fires to clear land for agriculture is the most well-known contributor to particulate matter, but there are other culprits as well. The excessive use of nitrogen-based fertilizer, for example, leads to ammonia emissions - which can in turn mingle with urban emissions to produce particulate matter in cities in places including the US, China, and India. These and other agricultural emissions also contribute to acid rain and eutrophication (which causes excessive algae) in downwind waters.


Shifting to plant-based diets would reduce overall agricultural emissions, there are a variety of strategies for reducing emissions from animal agriculture - including changes in livestock feeding, manure storage, and manure spreading techniques, and controlling emissions from animal housing.

Would you believe that Rice cultivation also produces pollution? Well, it does, methane-related if rice fields are flooded, and nitrous oxide-related with intermittent flooding. Methane contributes to ozone, and both contribute to global warming. The manure produced in animal agriculture is also a major source of ammonia emissions, while livestock digestion is a bigger contributor to global methane emissions than oil and gas production. Ultimately, shifting to cultivation approaches that use less fertilizer and reduce the tilling and burning of fields can reduce farming-related emissions.

According to the International Energy Agency, energy production and use account for 85% of the world’s particulate matter - and nearly all of the Sulphur oxides and nitrogen oxides damaging health and changing the climate. We need clean electricity, and we need it now.


Oil and gas operations, for example, account for about a quarter of all human-generated emissions of methane, a powerful climate warming agent. Coal power plants, which emit mercury and arsenic in addition to particulate matter and greenhouse gases, contribute to hundreds of thousands of premature deaths annually. These emissions can be controlled, but the majority of the world’s power plants do not have the technology necessary to do so.


Emissions from trucks and automobiles are a significant contributor to urban air pollution, and shipping produces trails of pollution across oceans that are visible to satellites. The fuels used for industrial production and heating also matter; boiler systems produce particulate matter, and are leading contributors to pollution. Gaps in energy access can increase the pollution load; the World Health Organization estimates that more than three billion people relying on solid fuels like coal for cooking and heating suffer from indoor air pollution as a result.


We need a systemic transformation, from source to use, that simultaneously expands access to energy and reduces climate- and health-damaging emissions across entire supply chains. While so-called “top of smokestack” and “end of tailpipe” emissions controls have delivered cleaner air where related technologies have been implemented, properly regulated, and maintained, we need to reach deeper and earlier within the global energy system to meet the twin challenges of energy expansion and emission reduction.


Burning is an inefficient way to extract energy, whether in a car, boiler, or traditional cookstove. We need to increase the efficiency with which we convert raw energy to productive use, transition as much as possible to lower-emitting forms of energy use by eliminating nearly all combustion, and control emissions at later stages where they cannot be eliminated earlier in the system.


In simple terms, this means electrify more. By cleaning up electricity - that is, by increasing the share of renewables and controlling emissions from residual gas or coal, and by focusing innovation and entrepreneurial efforts on converting legacy fossil fuel infrastructure, we can speed up necessary changes.

Air Pollution Governance

Air Quality and the Circular Economy


We can clean up the air. This is not the time for DIY when it comes to air quality. We have most of the necessary technology, and we know how to use it. However, accelerating the shift to new ways of powering industry, running households, moving around, growing food, and disposing of waste will require regulation, strategic investments, and collaboration.


Atmospheric processes - winds that carry pollution, rains that wash it out, and solar radiation that speeds up chemical reactions - affect the way emissions happen in one place and air pollution affects another. In order to effectively tackle pollution, we need to deploy agile governance to untangle this puzzle. In many urban areas cars and trucks are the major culprit, but burning waste, pizza ovens, and diesel backup generators can also create dangerous hotspots.


Pollution moves across boundaries, from local to regional and even on to hemispheric scales. It mixes, too - ammonia from fertilizer used in fields combines with nitrogen oxides from industrial activity, cars, heating systems, and electricity grids to contribute to particulate matter loads around the world, in developing and developed economies. Sometimes it even seems to disappear all by itself, when the winds and rains are just right.


This pollution puzzle is getting easier to solve, as satellites continue to open new possibilities to quickly, accurately, and consistently detect it. Still, we have to work across boundaries to improve air quality. Tracing pollution back to its source will inevitably draw leaders across borders - to a neighbouring city, state, or country, in order to find fellow policy-makers with the power to reduce emissions.


While air pollution-related problems and political contexts differ among cities and nations, we have a shared set of experiences available to learn from. The international Convention on Long-Range Transboundary Air Pollution, the regional South Coast Air Quality Management District in California, and Mexico City’s Environmental Commission of the Megalopolis have all provided models. There is also a dense patchwork of regional & sectoral agreements ready to be woven more tightly together in order to better tackle transboundary pollution.


 And there is a growing amount of experience with a range of control technologies and policy approaches, including setting and enforcing ambient air quality standards, emission standards for particular sources such as power plants and motor vehicles, and emission trading schemes that have used market mechanisms to bring down overall costs.

Out of sight should not mean out of mind when it comes to pollution. The health effects of air pollution may be local, but its environmental impact extends around the globe. Integrating efforts to eliminate air pollution in supply chains, recycling systems, and waste management services could move us towards a more circular economy - which involves re-using materials rather than disposing of them.


A substantial portion of air pollution stems from consumption that takes place far from the site of impact. The burden of these emissions is also likely to fall on disproportionately on poor, disadvantaged communities living near industrial sites.


According to one estimate, nearly a fifth of the premature deaths attributed to particulate matter in China are associated with the production of goods exported to the rest of the world - and more than half of all polluting emissions are tied to goods consumed outside the provinces bearing the impact of related pollution.


The same relationship holds true in other countries; in the US, for example, research has suggested that ethnic minorities are exposed to as much as 60% more pollution than what is associated with the goods they actually consume. Sadly, the competitive forces driving low-cost global production are directly at odds with efforts to protect vulnerable communities.


The World Bank has estimated that least a third of the waste produced around the world, and 90% of the waste generated in low-income countries, is disposed of through open dumping or burning - or both. These disposal methods contribute to a variety of pollutants, including burning particulate matter, air toxics, ozone precursors (chemical compounds that react to form ozone), and climate pollutants. Similar to the dynamic with production, our current approaches to managing waste also contribute to air pollution that often affects communities far from the site of consumption.


The effects of waste burning on nearby communities are particularly severe, since pollutants can transfer from the air to water, the soil in playgrounds, and just about any other surface. Similarly, unofficial recycling and even well-intentioned but poorly managed composting can create air, water, and soil pollution hotspots.


Accelerating the transition to a circular economy, and better managing the entire lifecycle of resources would nicely complement traditional regulatory approaches and help focus investment. We must shift from a spatial to a systemic focus when it comes to managing pollution, in order to avoid simply moving it from one place to another.



One of our era's greatest scourges is air pollution, on account not only of its impact on climate change but also its impact on public and individual health due to increasing morbidity and mortality. There are many pollutants that are major factors in disease in humans.


Among them, Particulate Matter (PM), particles of variable but very small diameter, penetrate the respiratory system via inhalation, causing respiratory and cardiovascular diseases, reproductive and central nervous system dysfunctions, and cancer. Despite the fact that ozone in the stratosphere plays a protective role against ultraviolet irradiation, it is harmful when in high concentration at ground level, also affecting the respiratory and cardiovascular system.


Furthermore, nitrogen oxide, sulfur dioxide, Volatile Organic Compounds (VOCs), dioxins, and polycyclic aromatic hydrocarbons (PAHs) are all considered air pollutants that are harmful to humans. Carbon monoxide can even provoke direct poisoning when breathed in at high levels. Heavy metals such as lead, when absorbed into the human body, can lead to direct poisoning or chronic intoxication, depending on exposure. Diseases occurring from the aforementioned substances include principally respiratory problems such as Chronic Obstructive Pulmonary Disease (COPD), asthma, bronchiolitis, and also lung cancer, cardiovascular events, central nervous system dysfunctions, and cutaneous diseases.


Cleaning the air means improving health, mitigating climate change, and protecting biodiversity. Climate change resulting from environmental pollution affects the geographical distribution of many infectious diseases, as do natural disasters. The only way to tackle this problem is through public awareness coupled with a multidisciplinary approach by scientific experts; national and international organizations must address the emergence of this threat and propose sustainable solutions.


The effects of air pollution are profound, and often under-recognized (though decreased mobility during COVID-19 provided a vivid glimpse of what's possible if the problem is properly addressed). The burden of pollution tends to be greater for poorer nations, and for marginalized groups in high-income countries. But the good news is that we can eliminate much of this pollution with existing technologies and practices, and at a surprisingly low cost - if we strategically invest in infrastructure, services, and incentives.


Thanks to continuing advances in air pollution detection and analytics, we will increasingly have the intelligence necessary to drive positive change.

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