Table of Contents
Introduction
Air pollution is one of the most direct ways in which energy systems affect human health. While climate change works through long term global processes, polluted air harms people locally and often within hours or days. In the context of renewable energy and sustainability, understanding air pollution and its health impacts helps explain why shifting away from fossil fuels delivers immediate benefits for people, not only for the climate.
This chapter focuses on what air pollution is, how it relates to energy production and use, and what kinds of health problems it causes. It also highlights how cleaner energy choices can reduce these impacts.
What Air Pollution Is
Air pollution refers to harmful substances in the air at concentrations that damage health, ecosystems, or materials. These substances can be gases or tiny particles. Some are released directly from sources such as engines or power plants. Others form in the atmosphere when different chemicals react under sunlight.
From an energy perspective, the biggest contributors to air pollution are the burning of coal, oil, and gas in power plants, industry, transport, and buildings, along with traditional biomass burning such as wood and charcoal in inefficient stoves.
Key Air Pollutants Linked To Energy Use
Several pollutants are especially important when considering health effects from energy systems.
Sulfur dioxide, often written as $SO_2$, mainly comes from burning coal and heavy oil that contain sulfur. In the atmosphere, $SO_2$ can react with water and other substances to form fine particles and acid compounds. These contribute to smog, acid rain, and respiratory irritation.
Nitrogen oxides, often written as $NO_x$, include nitric oxide ($NO$) and nitrogen dioxide ($NO_2$). They form when fuel burns at high temperatures, for example in vehicle engines or gas turbines. $NO_x$ helps create ground level ozone and fine particles, and $NO_2$ itself irritates the lungs.
Particulate matter, usually abbreviated as $PM$, describes microscopic solid and liquid particles suspended in air. A common way to classify them is by size. $PM_{10}$ includes particles with a diameter up to 10 micrometers. $PM_{2.5}$ includes particles up to 2.5 micrometers across, roughly one thirtieth the width of a human hair. $PM_{2.5}$ is especially dangerous because it can penetrate deep into the lungs and even enter the bloodstream. These particles come from combustion in power plants, cars, trucks, ships, industrial boilers, and household stoves, but also from secondary formation from $SO_2$ and $NO_x$.
Ground level ozone, written as $O_3$, is different from the protective ozone layer high in the atmosphere. At ground level, $O_3$ is a secondary pollutant that forms when $NO_x$ and volatile organic compounds react under sunlight. Many of these precursors originate from fossil fuel use and industrial processes. Ground level ozone irritates the airways and reduces lung function.
Carbon monoxide, written as $CO$, is a colorless and odorless gas produced by incomplete combustion, especially in poorly ventilated stoves, engines, and heaters. At high levels, $CO$ interferes with the blood’s ability to carry oxygen.
There are also toxic metals such as mercury, lead, and arsenic that can be released when coal or certain wastes are burned. These may attach to particles and be inhaled or deposited on soil and water, later entering food chains. Some organic compounds from combustion, such as polycyclic aromatic hydrocarbons, are also of concern because of their potential to cause cancer.
Indoor Versus Outdoor Air Pollution
Air pollution is often imagined as outdoor smog over cities and industrial regions. However, indoor air pollution can be just as serious, especially in homes that rely on traditional fuels.
Outdoor, or ambient, air pollution comes from power plants, vehicles, factories, construction sites, open burning of waste, and other sources. It affects people living or working nearby, as well as those downwind, since polluted air can travel over long distances.
Indoor air pollution arises inside buildings when people burn biomass or coal for cooking and heating in simple stoves or open fires, or when there is poor ventilation of gas heaters, kerosene lamps, or generators. Smoke and gases accumulate within the living space and reach very high concentrations. In many low and middle income countries, this type of exposure is one of the largest environmental health risks, especially for women and children who spend more time indoors near the stove.
From a renewable energy perspective, both indoor and outdoor pollution can be reduced by cleaner cooking technologies, electrification with clean power, improved building design, and more efficient devices.
How Pollutants Enter And Affect The Body
When people breathe polluted air, particles and gases enter the respiratory system. Larger particles are trapped in the nose and upper airways, but fine particles such as $PM_{2.5}$ can reach deep into the lungs and even cross into the bloodstream. Gases like $NO_2$, $SO_2$, and ozone dissolve in the moist surfaces of the airways and cause irritation and inflammation.
Once inside the body, pollutants can trigger several biological responses. Inflammation in the lungs can make breathing more difficult and worsen existing diseases like asthma and chronic obstructive pulmonary disease. Fine particles can contribute to the buildup of plaques in blood vessels, which increases the risk of heart attacks and strokes. Some chemicals attached to particles can damage DNA and cellular processes, which increases the risk of cancer over time.
It is important to note that there is no single threshold below which air pollution is completely safe for everyone. Even low levels can affect sensitive individuals such as children, older adults, and people with existing heart or lung disease. Health impacts also depend on how long and how often people are exposed, and on the mixture of pollutants in the air.
Short-Term And Long-Term Health Effects
Health effects from air pollution occur over different timescales. Short term exposures, especially during pollution peaks, can cause immediate symptoms. Long term exposures, over months and years, increase the chance of chronic diseases.
In the short term, exposure to high pollution levels can cause coughing, wheezing, shortness of breath, sore throat, and eye irritation. People with asthma may have more frequent or severe attacks, leading to increased use of medication or visits to emergency departments. On days with very high $PM_{2.5}$ or ozone, cities often see a rise in hospital admissions for heart and lung conditions.
Over the long term, sustained exposure to polluted air increases the risk of chronic bronchitis, chronic obstructive pulmonary disease, lung cancer, heart disease, stroke, and possibly diabetes and certain neurological conditions. In children, long term exposure can slow lung development and may affect cognitive development. In older adults, it can accelerate the progression of existing cardiovascular and respiratory diseases.
Many health studies show that even moderate reductions in average $PM_{2.5}$ levels across a city or region are associated with longer life expectancy and fewer hospital admissions. This means that policies which clean up energy sources can quickly translate into measurable health benefits.
Measuring Air Pollution And Health Risks
To understand and manage the health impacts of air pollution, scientists and authorities rely on monitoring and standards. Concentrations of pollutants such as $PM_{2.5}$, $PM_{10}$, $NO_2$, $SO_2$, $O_3$, and $CO$ are measured in micrograms per cubic meter, written as $\mu g/m^3$, or in parts per billion for gases. Monitoring stations placed across a city or region provide continuous data, which can be compared to air quality guidelines.
Many organizations define recommended limits for average concentrations over one hour, one day, or one year. These guidelines are based on large epidemiological studies that link pollutant levels to health outcomes such as premature mortality or hospital admissions. Although specific numerical values belong to policy discussions, the general principle is that lower concentrations reduce health risks, and incremental improvements are worthwhile even if guidelines are not yet fully met.
Researchers often estimate the health burden of air pollution by combining data on pollution concentrations, population exposure, and known relationships between exposure and health outcomes. This approach can show how many cases of disease, hospital visits, or premature deaths could be avoided by reducing pollution, for example by phasing out coal power in a region or replacing traditional cookstoves with cleaner alternatives.
Special Vulnerable Groups
Air pollution does not affect everyone equally. Certain groups are more vulnerable because of biology, behavior, or social conditions.
Children breathe more air per unit of body weight and spend time outdoors, so they receive higher doses relative to their size. Their lungs and organs are still developing, so damage at an early age can have lifelong consequences.
Older adults are more likely to have existing heart or lung conditions that can be worsened by pollution. Their bodies may also have reduced ability to repair damage from inflammation and oxidative stress.
Pregnant women and their fetuses are another sensitive group. Exposure to high pollution levels during pregnancy has been associated with lower birth weight and increased risk of certain complications.
People with pre existing respiratory or cardiovascular diseases, such as asthma, chronic obstructive pulmonary disease, or coronary artery disease, are more likely to experience severe effects during pollution episodes. They may experience more symptoms, need more medication, or require emergency treatment.
Finally, people living in poverty often have higher exposure and fewer resources to protect themselves. They may live near busy roads, industrial sites, or power plants, and may also rely on polluting fuels for cooking and heating indoors. This combination increases their overall health risk.
Air Pollution From Fossil Fuels And Biomass
Energy production and use is a major driver of air pollution. When coal, oil, gas, and traditional biomass are burned for power, heat, transport, or cooking, they release pollutants directly into the air.
Coal fired power plants are among the largest single sources of $SO_2$, $NO_x$, $PM$, and toxic metals. Without effective emission controls, they create regional haze and contribute to respiratory and cardiovascular diseases in surrounding populations. Even with modern filters and scrubbers, some emissions remain.
Oil and diesel used in vehicles, shipping, and back up generators emit $NO_x$, $PM$, and a range of organic compounds. In cities with heavy traffic, vehicle emissions are a main contributor to $NO_2$ and urban $PM_{2.5}$, as well as to ground level ozone formation.
Natural gas combustion is generally cleaner than coal or oil in terms of $SO_2$ and particles, but gas turbines and engines still emit $NO_x$. In addition, leaks of methane, the main component of natural gas, affect climate, although this belongs to greenhouse gas discussions rather than local air quality.
Traditional biomass burning in open fires or simple stoves, such as wood, charcoal, dung, and crop residues, produces large amounts of smoke, $PM_{2.5}$, $CO$, and organic pollutants. In many rural and peri urban homes, this leads to extremely high indoor concentrations and harms the health of household members.
These pollution sources are often concentrated near or within communities with fewer resources and less political influence, which links air pollution to broader questions of environmental justice.
Health Co-Benefits Of Renewable Energy
Shifting to renewable energy sources can significantly reduce air pollution and its health impacts, especially when renewables replace the most polluting fossil fuels and traditional biomass. The exact benefits depend on the technology and how it is implemented.
Solar photovoltaic systems and wind turbines generate electricity without combustion, so they emit no direct $SO_2$, $NO_x$, or $PM$ during operation. By displacing coal and oil based power, they can reduce regional air pollution and lower the incidence of respiratory and cardiovascular diseases. There are still emissions associated with manufacturing and construction, but these are usually much smaller and occur away from the point of use.
Hydropower and most geothermal uses also avoid combustion emissions during operation. However, certain geothermal systems can release small amounts of gases or minerals, which must be managed. Similarly, some bioenergy pathways can reduce net emissions if they use clean, efficient combustion with proper controls, but if designed poorly, they can worsen air quality.
Electrification of transport, buildings, and industry with clean electricity further magnifies health benefits. For example, replacing diesel buses with electric buses removes exhaust emissions from streets and reduces $NO_2$ and $PM$ along busy routes where many people are exposed. Replacing traditional cookstoves with electric or advanced clean stoves can dramatically cut indoor air pollution and reduce respiratory disease among women and children.
These improvements in air quality are often described as health co benefits of climate and energy policies. They mean that even if climate change were not a concern, there would still be strong reasons to reduce fossil fuel use simply to protect public health.
Rule of thumb: Replacing combustion based energy with truly clean renewables tends to reduce $PM_{2.5}$, $SO_2$, and $NO_x$ levels, which in turn lowers rates of respiratory and cardiovascular disease and increases life expectancy.
Monitoring, Information, And Public Health Measures
Beyond changing energy systems, there are practical steps that public health agencies and individuals can take to reduce the health impacts of air pollution.
Authorities can expand and improve air quality monitoring networks, publish real time pollution data, and issue health advisories during high pollution episodes. These advisories can encourage people, especially vulnerable groups, to limit outdoor activity when pollution is high. In some cases, temporary measures such as traffic restrictions or industrial curtailments are used to reduce peaks.
Health professionals can be trained to recognize pollution related symptoms and advise patients on protection strategies. These may include using cleaner cooking options, improving ventilation, avoiding heavy exercise near busy roads, and using indoor air filtration systems when appropriate.
At the same time, information campaigns can help build support for cleaner energy policies. When people understand that air pollution contributes to heart attacks, strokes, and childhood lung problems, they may be more likely to support measures that restrict the most polluting fuels and encourage renewables and efficiency.
Linking Air Pollution To Sustainability Decisions
Planners and decision makers in energy and urban development increasingly include air pollution and health impacts in their assessments. This is closely related to life cycle and environmental impact assessments, but with a specific focus on local health outcomes.
When comparing different energy options, it is important to consider not only cost and climate impacts, but also how much $PM_{2.5}$, $NO_x$, $SO_2$, and other pollutants they will emit over their lifetime and how many people live nearby. A small reduction in emissions in a densely populated city can sometimes have a larger health benefit than a similar reduction in a remote area.
Policies that prioritize low emission technologies, clean fuels, and efficient devices help move energy systems onto a more sustainable path. They can also reduce health inequalities by cleaning up air in communities that have historically borne the highest pollution burdens. In this way, addressing air pollution from energy use is not only a technical challenge, but also an ethical and social one.
Conclusion
Air pollution is a major channel through which current energy systems affect human health. Pollutants such as $PM_{2.5}$, $NO_2$, $SO_2$, $O_3$, and $CO$, largely produced by combustion of fossil fuels and traditional biomass, are linked to a wide range of diseases and premature deaths. Indoor and outdoor pollution together pose serious risks, especially for vulnerable groups.
Renewable energy technologies that avoid combustion during operation, along with cleaner end use devices and electrification, offer a powerful way to reduce these risks. When societies evaluate energy choices through the lens of air pollution and health, the case for a rapid transition to cleaner, more sustainable systems becomes even stronger.