Problems with air pollution and air quality have been known for millennia, but the attitude towards them has been ambiguous. To a certain extent, air pollution was considered a sign of economic prosperity and growth, and the attempts to combat them were ineffective. Since the Clean Air Act of 1970, which regulated air emissions in any form and by any source, and subsequent amendments in 1990, air quality in the United States has been relatively protected from the absolute worst pollutants, subsequently improving industrialized air.
However, since then, the world has developed drastically—the global population has more than doubled, the number of people living in cities has increased by more than a factor of four, the global energy consumption by nearly a factor of five, and there are now globally about ten times as many cars as 50 years ago (Fenger, J. 2009). Despite past efforts, this scenario has presented an increase in air pollution that now threaten nature and mankind across the entire Earth.
The thin shell of gases, particles, and clouds that surrounds our planet, otherwise known as the atmosphere, is where we dump several billion tons of pollutants each year. The main sources of this pollution include fossil fuel combustion for energy generation and transportation, cooking with solid fuels, and burning of forests and savannah (Ramanathan, V. & Feng, Y., 2009). The largest problems of air quality are now mostly seen in developing countries with megacities, but there are still issues in the industrialized world mainly connected to growing traffic which produces nitrogen oxides (NOx), volatile organic compounds (VOCs), and photochemical oxidants, which are the products of reactions between NOx and VOCs.
The main photochemical oxidant that impacts the natural environment is mostly due to ozone (O3). In addition to this, new hazardous compounds from industry have recently been identified, and agriculture has also become an important air pollution source from organic fertilizing and pig production (Fenger, J. 2009).
Climate change affects surface concentrations of air pollutants, such as fine particulate matter (PM2.5) and O3 (Fang, Y., et. al., 2013). PM2.5 can be directly emitted from sources such as forest fires, or can form when gases emitted from power plants, industries, and automobiles react in the air. PM10, a smaller inhalable particle, is found near roadways and dusty industries. Both of these particulate matters cause negative health effects, reduced visibility in the air, environmental damage, and aesthetic damage (Keuken, M.P., et. al, 2013).
According to a global study conducted by Lelieveld, J. et. al. (2015), residential and commercial energy use is the largest air pollution source category worldwide, contributing to one third of it. The next largest anthropogenic source category is agriculture, contributing one-fifth, followed by power generation, industry, biomass burning, and land traffic. In addition to greenhouse gases, human activities also contribute to the addition of aerosols (condensed particles in submicron size to the atmosphere). Aerosols start off as urban haze or rural smoke, and eventually become transcontinental and trans-oceanic plumes consisting of sulfate, nitrate, hundreds of organics, black carbon, and other aerosols (Ramanathan, V. & Feng, Y., 2009).
Every part of the world is connected with every other part through fast atmospheric transport (Ramanathan, V. & Feng, Y. 2009). Depending on the lifetime of the particulate, air pollutants can be transported by atmospheric winds from one country to another within a week, whether the emissions are from Asia, North America, or Africa (Kumar, R., 2016; Ramanathan, V. & Feng, Y. 2009; Akimoto, H., 2003). Because the atmospheric lifetime of ozone is 1-2 weeks in the summer and 1-2 months in the winter, ozone produced in a polluted region of one continent can be transported to another continent all year long. Aerosols lifetimes, on the other hand, are approximately 1-2 weeks, but have a more uneven distribution than ozone both horizontally and vertically, and are more concentrated near their source regions over continents and in the boundary layer. The more uneven distribution of tropospheric aerosols causes highly heterogeneous radiative forcing, which can lead to climate effects occurring regionally as well as globally (Akimoto, H., 2003). This means that pollution occurring in a certain part of the world can have impacts in another part.
Air pollution is a major global environmental threat and poses real risk to our health and security. It is estimated to cause about 3.7 million premature deaths worldwide and destroy enough crops to feed millions of people every year (Kumar, R., 2016). According to a WHO assessment, more than half of this burden is maintained by the populations of developing countries (World Health Organization, 2005). The effects of air pollution reaches many parts of a human’s body, but is mainly linked to life threatening cardiovascular and pulmonary illnesses, causing irritation to the lungs and airways, leading to lung cancer, chronic obstructive pulmonary disease, and asthma, especially if inhaled as a child. It is also known to increase the risk of heart attack, stroke, abnormal rhythms, and ischemic heart disease, as well as the increased risk of getting Type 2 Diabetes, and can even affect a woman’s fetus, causing abnormal development, premature birth, still births, and autism (Bereitschaft, B. & Debbage, K., 2013; Keuken, M.P., 2013; Lelieveld, J. et. al., 2015; Guttikunda, S. & Goel, R., 2012; Gaffney, J. & Marley, N., 2009).
While the United States follows more strict air quality guidelines, the UK government has been in breach of EU air quality limits since 2010 and now faces multimillion pound fines at the European Court. This has caused Europe to currently experience air pollution as the “biggest environmental risk” to public health. In fact, toxic air kills an estimated 400,000 Europeans each year—up to 40,000 of them in Britain (Nelson, A., 2018). In the Indian region, it has been estimated that surface ozone pollution destroys enough food to feed about 94 million people and leads to around 0.9 million premature deaths each year. The profound economic damage associated with health and crop impacts of the air pollution in India are estimated to be more than 2 billion USD (Kumar, R., 2016). However, the United States is definitely not off the hook. According to a study conducted by Muller, N. et. al. (2011), the authors estimated the aggregate air pollution damages, Gross External Damages (GED), from the market sector of all US industries in 2002, finding total damages of $184 billion with agriculture maintaining 38% of the damages and utilities contributing 34%.
Air pollution is not just costing us billions of dollars and thousands of lives, it is also contributing to degradation of our landscapes, decreased air visibility, and acid rain (Bereitschaft, B. & Debbage, K., 2013). Particulates impact the environment by making lakes and streams acidic, changing the nutrient balance in coastal waters and large river basins, depleting the nutrients in soil, damaging sensitive forests and farm crops, and affecting the diversity of ecosystems (Keuken, M.P., 2013). These affects can be seen in remote areas of East Asia, where its average concentration of ozone is already high enough to jeopardize agricultural and natural ecosystems. What is worrisome about this is the fact that the elevation of background levels of ozone by long-range transport can cause additional ozone to be produced locally or regionally in amounts that would not otherwise have been critical. This makes small increments of ozone concentrations caused by contributions from other continents an issue of great concern (Akimoto, H., 2003).
The massive health, environmental, and economic impacts from air pollution coupled with exponential population growth provides plenty of incentive to tackle this problem within the next decade. The urban population, which contributes to large amounts of air quality issues, is expected to grow rapidly from 3.6 billion in 2010 to 5.2 billion in 2050 (Lelieveld, J. et. al, 2015), which will cause health and environmental impacts to escalate. This is evident from Lelieveld, J. et. al. (2015) findings that the per capital mortality attributable to air pollution is 50% higher in urban than in rural environments, and under a Business as Usual scenario, this difference is expected to increase to nearly 90% in 2050 if no changes are made.
In addition to this, Chemistry-climate models (CCM) provide a more integrated way to examine climate change impacts on surface air quality as they allow coupling and feedbacks between dynamics, chemistry, and physics, all of which directly affect air pollutant levels. These CCM studies suggest that PM2.5 and aerosol concentrations may increase in a warmer climate because of stratiform precipitation, suggesting that climate change intensifies air pollution and its impacts (Lelieveld, J., et. al., 2015).
The increase in population also has implications for megacities who already suffer from high levels of pollution and degraded air quality to the high demand for energy and the associated combustion in mobile and stationary sources. They therefore are huge sources of air pollutants into the surrounding regional areas. It is predicted that if the population growth trend continues, the world’s urban populations will double every 28 years and within the next 10-15 years there would be more than 30 megacities worldwide (Gaffney, J. & Marley, N., 2009). The local, regional, and global air quality issues, and regional and global environmental impacts, including climate change, should therefore be viewed in an integrated manner in order to attempt a sustainable outcome in the future.
The lack of uniform air quality standards across the globe has led to very uneven practices. In Europe, the standards are established by the EU and have mainly been neglected by the government, and in many developing countries, air quality is not even addressed. The example set by developed countries is not a promising one, and if we continue to follow this trajectory, serious premature mortalities, hunger, and environmental degradation will persist. As stated earlier, megacities will continue to hold a host of pollution issues, while future increases of emissions from Africa and South Africa would also make global air quality more of an issue in the Southern Hemisphere, a region where only biomass burning has been considered important thus far (Akimoto, H., 2003).
In a study conducted by Fang, Y. et. al. (2013) the authors simulated climate changes in North America, Europe, and South and East Asia, finding that it induced changes in both PM2.5 and O3 surface concentrations that are projected to increase premature mortality under the scenario of constant population, baseline mortality rate, and emissions of short-lived air pollutants. They found that climate change generates an air quality “climate penalty” by increasing surface concentrations of air pollutants and associated human health risks. As a result, stronger emission controls will be needed in many regions to maintain current air quality and public health, otherwise, premature mortality will result from higher temperatures, insufficient food supply, and greater malarial risk.
Air quality is now regulated by standards based on experiments on humans and/or animals and epidemiological investigations evaluated by WHO and expressed in the form of guidelines (Fenger, J., 2009). However, the US government has not enacted federal legislation to regulate GHG emissions and WHO guidelines are not a global standard. Because GHGs mix globally and have global impacts, local abatement actions pose local costs, yet deliver essentially no local climate benefits, suggesting local actions can be difficult to enact—unless cooperation can be organized. Although state-level efforts can be moot, entities can take action through multiple different measures in an effort to “think globally, act locally,” but it seems as though only international cooperation on emissions limitations can effectively reduce pollutant concentrations (Wiener, J., 2007).
Air pollution is currently regulated through various ways: by emission standards, by air quality standards, by emission taxes, and by cost-benefit analyses. The classical way is to limit the emission from a source, a sector, or an entire country, although this has been attempted for centuries with limited success. Emission taxes have also been attempted, but are met with moral objection that it should not be possible to buy the right to pollute (Fenger, J., 2009).
Nevertheless, if well-designed, subnational state-level strategies could yield some payoffs, including stimulating technological innovation that can diffuse to other unregulated places, learning by experimentation with alternative policy designs, and raising the awareness of inconsistent state regulations as a political scheme to motivate industry to support broader federal regulation (Wiener, J., 2007).
As discussed above, Wiener (2007) suggests that local policies for emissions could have negative feedback processes at the global scale. However, the local strategies can have global benefits by stimulating technology that could diffuse to other countries through sharing and learning from successful policies. Therefore, I would suggest to implement a strategic approach through coupling local activities with overarching international strategies.
In order to ensure uniform regulation across the globe, an international overarching strategy should be implemented that is similar to WHO guidelines, yet including the entire globe. Holding countries accountable to their individual GHG emissions could promote friendly competition that entices national governments to increase their air quality. This would also stimulate developing countries to implement effective practices at the onset of economic growth.
With an overarching uniformity, governments could therefore implement local practices that could spread effective GHG emission relief. For example, technical elements can be implemented to make a city’s building stock more heat resistant such as using trees to provide shading and reducing urban heat islands, greening façade and rooftops, installing open water bodies, and increasing LEED values of buildings. In addition to this, symbolic elements could have heavy weight, including mission statements for urban development, environmental assessments, comprehensive land-use plan and landscape programs, urban development contracts, and design regulations. The only way to ensure implementation, however, is through the thorough education and participation of local stakeholders. By getting community members involved, more value and effectiveness can be added to local plans.
Global air pollution presents a host of environmental, health and economic impacts, and the problem is only growing with the presence of population growth. At this rate, premature mortality and environmental degradation will continue to increase without the implementation of global remedial efforts. Past regulations have allowed for industrialized air to become somewhat regulated in North American cities, but urban air is still emitting enough GHGs to cause detrimental effects through atmospheric transport that connects air pollution to all countries across the globe. With the increasing number of megacities, this urban air will only continue to emit more and more pollution. The interconnectedness of air quality calls for a complex local to regional to global solution that can be very difficult to implement, but if efforts are not attempted, we could end up in a much worse place than we are currently.