Top 5 Most Polluting Industries- And What They’re Doing About It

Written by

Ciaran Wark

Last updated

13 March 2024

According to the Lancet, environmental pollution caused 9 million deaths worldwide in 2019.  

Globalisation has allowed industries to expand, meaning nowadays, supply chains are far more vast and levels of production have skyrocketed. This has exacerbated the levels of pollution, climate change, and negative human health impacts linked to these industries. 

In this article, we’ve identified the top 5 most polluting industries, based on levels of greenhouse gas emissions (GHG) measured in 2019, according to Our World in Data. 

We are also interested in understanding what these industries are doing to decarbonise, reduce levels of pollution, and sustainably manage the resources they exploit. 

In most cases, some key technologies are making their way to becoming industry standards, provided that supportive policy and sizeable investments are put into place. 

It’s also clear that these industries are interlinked. This means common issues like energy usage across all industries is linked to the exploitation of fossil fuels. Therefore, transitionary measures, or national targets, that reduce fossil fuel use would impact most industries. 

Our Approach

To measure the levels of pollution, we’ve analysed some key indicators related to all, or some, of these industries. These include:

• Greenhouse gas emissions 
• CO2 emissions 
• Biodiversity loss 
• Water stress 
• Crude deaths 
• Levels of waste 

CO2, CO2eq, or GHG? 

Greenhouse gasses absorb and re-emit heat, which then warms the surface of the planet, ie. global warming. GHGs do occur naturally, but industrial activities such as deforestation or burning fossil fuels increase GHG emissions which rapidly accelerates the rate of global warming. 

Greenhouse gas emissions are measured in carbon dioxide equivalents (CO2eq). This bundles non-CO2 gases in one unit, based on the amount of CO2 that would cause the equivalent global warming impact. Other examples of greenhouse gas emissions include methane (CH4), and nitrous oxide (N2O). 

Carbon dioxide is the most commonly emitted GHG, accounting for about 74% of total global emissions, according to Our World In Data. Therefore, CO2 emissions are often measured alone. Throughout this article, emissions from CO2 and GHG have been included. 

Types of Pollution 

CO2 and GHG emissions are effective measures of global warming, but this is not the only indicator of pollution. That’s why we’ll look into the impacts on air, water, and land to understand the scope of pollution from these industries. 

Air pollution 

Air pollution is the most severe type of pollution given the danger air pollutants (such as CO2, methane, and particulate matter) cause to human health and global warming. 

According to the World Health Organisation, 7 million deaths per year have been linked to air pollution. Pollution in the air has been proven to impact infant mortality rates, respiratory disorders, mental health disorders, among many more. 

Air pollution is most prevalent in urban areas, identified by levels of smog, but toxic particulate matter can be found in even the most rural areas. 99% of people currently breathe air that exceeds the WHO’s guideline limits for pollutants. People living in low- and middle-income countries are the most affected.

Water pollution

Water pollution is the contamination of waterways or bodies of water in the environment. Water pollution degrades water quality which impacts human health and the health of ecosystems.  

Common pollutants include nutrients and chemicals from agriculture, leached contaminates from landfills, toxic dyes and microplastics from waste, or oil pollution from industrial spills, 

Water pollution has many effects: 

• Human health impacts: diseases such as cholera and typhoid from human and animal waste
• Eutrophication: the presence of industrial residues in water depletes oxygen levels and starves marine and plant life
• Ocean acidification: the oceans absorb CO2 from the atmosphere altering the pH levels and impacting marine life and food chains 
• Chemical and heavy metal contamination 
• Marine waste starving or suffocating marine life

Soil pollution 

Soil becomes polluted from agricultural residues, such as manure and pesticides, industrial waste, such as heavy metals and urban waste. 

Pollution in the soil causes biodiversity loss, contamination of water storage and nutrient depletion. Common agricultural practices such as monocropping lead to soil erosion which is largely irreversible and has catastrophic impacts on the global food system and climate change. 

With that being said, let’s look at the top polluting industries. 

1. Buildings (Heat and Electricity)

Energy in residential and commercial buildings provides heating, cooling, and power. The global energy (and electricity) mix is typically made from nuclear, renewable, or fossil fuel sources. 

In 2019, fossil fuels- as in natural gas, oil, and coal- still made up over 80% of the global energy supply. 25% of the CO2 emissions produced from burning these fossil fuels was used for heat and electricity in buildings. This put it ahead of transport and manufacturing in both cases. 

The generation of electricity in thermal power plants is another major source of pollution and climate change. In 2021, 64% of the global power mix came from thermal power generation, with a significant share used to power buildings. 

Thermal power plants emit huge amounts of nitrogen oxides, CO2, and other harmful pollutants. These power plants are also major water and land polluters. 

For example, when wastewater is discharged into waterways, ecosystems are disrupted from changes in water temperature. Toxic components of waste also kills marine life, or affects plant growth. 

 ^{IEA (2021), Greenhouse Gas Emissions from Energy Data Explorer: https://www.iea.org/data-and-statistics/data-tools/greenhouse-gas-emissions-from-energy-data-explorer}

^{IEA (2021), Key World Energy Statistics 2021: https://www.iea.org/reports/key-world-energy-statistics-2021}

^{United Nations, Facts and Figures: https://www.un.org/en/actnow/facts-and-figures}

Based on technologies available today, it is possible to switch to alternative sources of energy for heat and electricity. 

The best low-carbon heating option in most cases is to install a heat pump. However, different solutions will suit buildings differently. This will typically depend on the location, size and condition of the builiding. 

Therefore, a combination of new technologies are expected to replace traditional forms of heat in buildings. Other low-carbon options include biomass heating, ‘green’ hydrogen, or solar thermal systems for hot water. 

The cost to install a heat pump remains the primary challenge in ensuring widespread adoption. Currently, a traditional gas boiler costs significantly less upfront and so will appeal to more homeowners. 

What’s more, installing a heat pump might require significant energy-efficiency improvements to be made first. This means many existing buildings must undergo retrofits, which only adds to the overall costs. 

Governments and industry actors can help heat pumps become more commercially viable with the following measures: 

1. Minimum energy performance standards across buildings
2. Governments finance schemes (heat pump grants) to help cover costs
3. Redirecting investments from energy-intensive or fossil-fuel based building projects

Renewable electricity can be provided by installing domestic solar panels. Once installed, renewables provide a free renewable supply of electricity to a building. 

Renewable power capacity within the power mix has steadily reached new records year-on-year. According to the International Energy Agency (IEA), renewable electricity capacity is set to rise 60% from 2020 levels by 2026. This will match the capacity of fossil fuels and nuclear energy combined. 

2. Transport

As the global population increases, so too does our demand for transport, be it passenger travel or freight. The International Energy Agency (IEA) expects global transport to double by 2070. Car ownership rates will increase 60%, and demand for aviation (passenger and freight) will triple.

Modes of transport largely operate from burning petroleum products in combustion engines. This has created a huge air pollution problem, especially in urban areas.

Production of this fuel in refineries releases toxic gasses and creates air pollution. What’s more, these refineries spend huge amounts of energy and generate toxic waste which is still disposed of illegally in some cases. Then comes the direct emissions from burning the fuel in combustion engines to power transport. 

Of the various modes we use, road transport alone accounts for nearly 75%, or three-quarters of transport emissions. This amounts to 15% of CO2 emissions globally, with the majority of this coming from passenger travel. 

^{Our World in Data (2020), CO₂ and Greenhouse Gas Emissions: https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions}

^{IEA (2022), Transport, IEA, Paris https://www.iea.org/reports/transport}

Electric vehicles (EV) and hydrogen fuels offer the greatest potential in the coming decades to decarbonise road and rail. The IEA estimates that rail emissions can be eliminated by 2050 and emissions from cars and buses by 2070. 

In 2021, EV sales doubled from 2020 figures to 6.6 million. In the first quarter of 2022, sales were up 75% from the same period the year before. By 2030, 30% of road transport vehicles are expected to be electric vehicles, although 60% is needed to reach net zero CO2 emissions by 2050. 

According to the IEA, this growth can largely be attributed to policy support from governments which promote EV adoption, this could involve: 

• Subsidies and incentives, which doubled in 2021 globally to US$30 million. 
• Phase-out of combustion engines through target setting. 
• Vehicle efficiency or CO2 standards. 

However, to meet net zero targets, there must be vast upscaling across the EV supply chain. Meanwhile, all processes must remain sustainable and resilient. The IEA suggests funnelling private investments into sustainable mining practices, and fast-tracking permitting procedures.

EV charging infrastructure must also continue to expand to meet the production demands. Enhancing charging infrastructure and smart grid technology helps to support growing EV fleets.  

The electrification of public transport and widespread adoption of cycling need to become the norm in urban areas. Electric buses and trucks are emerging as a competitive alternative to combustion engines. However, this can be supported by effective policy, such as introducing minimum CO2 standards.

These alternatives vastly improve the quality of life in our cities. Implementing them improves transport routes, reduces pollution, and provides cheaper travel.

Most difficult to decarbonise is long haul road freight, aviation and shipping. Hydrogen fuel and electric batteries offer the most potential but will take some time to develop. This is due to the sheer power required to fuel these modes of transport. 

These sub-sectors will become the main source of emissions from transport as time goes on.  The IEA predicts that carbon capture and storage in other parts of the energy system will help stabilise these emissions in the future. 

3. Heavy Industry and Manufacturing

Manufacturing involves the extraction and processing of natural resources into material goods. Typical resources might include metals for electronics, or sand and gravel used in construction.

A functioning manufacturing system supports economic growth and underpins social progress. This helps improve the standard of living in countries everywhere. 

However, extraction of non-regenerative materials is often energy-intensive and happens at unsustainable rates. What’s more, it creates untenable amounts of air, soil and water pollution, as well as greenhouse gas emissions and damage to ecosystems. 

Therefore, the material and economic gains promised by large scale manufacturing actually result in a net loss for humanity.

This is especially the case considering the toll on human health industrial pollution creates. Respiratory disorders, cardiovascular disorders, and birth defects have been linked to industrial pollution. 

_{United Nations, Facts and Figures: https://www.un.org/en/actnow/facts-and-figures
Our World in Data (2020), CO₂ and Greenhouse Gas Emissions: https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions
National Library of Medicine (2021), Is industrial pollution detrimental to public health?: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8213381/#CR6}

The manufacturing industry must extract and process resources more sustainably. Meanwhile, it must also boost productivity to support growing economies and meet supply demands. 

Key to addressing these issues is improving the efficiency of operations across the lifecycle of the materials.

Improving the efficiency of the whole manufacturing system involves some key system-wide strategies: 

• Dematerialisation | savings and reduction of material and energy use.
• Re-materialisation | reuse, remanufacturing and recycling.

Standardising these strategies creates a circular economy where products are recycled, remanufactured, and redistributed. This helps improve production efficiency and saves precious resources. Currently, some companies incentivise products to be returned for money, where they can then be repaired for re-use. 

A circular economy also means there is less need for the materials, energy, land, water and waste associated with manufacturing. This is partly because the lifetime of products is prolonged, and continually restored. 

Fore-fronting alternative technologies through research and development can help establish a circular economy. Efficient technologies can also be supported by policies such as minimum efficiency standards. 

For example, industrial, low-carbon electricity is already available. Electric-arc furnaces can operate at over 1000°C heat, and use less electricity than blast furnaces, making them more efficient. These can be used for steel-making and melting. 

Steel, cement, glass and chemicals can be processed using energy from hydrogen. This is a low-carbon fuel that also burns at very high temperatures. 

Efficient manufacturing helps retain the value of the materials we use, which thus reduces environmental impacts. What’s more, associated costs are reduced and more jobs are created from scaling these technologies.

4. Agriculture

Our food system and wider land use activities must rapidly adapt in the face of many interlinked challenges. These include feeding a growing population, combating the worst effects of climate change, and reducing the industries environmental impacts. 

Changing climate and the prevalence of extreme weather events intensifies these issues. Most notably reduced crop yields exacerbates food shortages and depletes food quality. Changing climate zones also help spread diseases and infestations to further reaches of the planet. 

The mismanagement of land use is a major contributor to these climate problems. By-products such as fertilisers, pesticides, and manure create toxic run-off into the soil, and waterways. These by-products can also have harmful greenhouse gas effects. 

Around 22% of GHG global emissions came from agriculture, forest and other land use in 2019, half of this from deforestation, most of the rest coming from fossil fuel combustion.  

Practices such as monocropping also increases the risk of soil erosion. This, combined with extreme weather events, can lead to desertification. 

Industrial land use such as palm oil plantations, and mining are also major contributors to deforestation. This degrades the land, threatens biodiversity, and releases tonnes of CO2 into the atmosphere at an ever-alarming rate. 

^{Our World In Data, Greenhouse gas emissions per kilogram food: https://ourworldindata.org/explorers/food-footprints
Food and Agriculture Organisation of the United Nations, Key facts and findings: https://www.fao.org/news/story/en/item/197623/icode/
Our World in Data (2020), CO₂ and Greenhouse Gas Emissions: https://ourworldindata.org/co2-and-other-greenhouse-gas-emissions
Our World in Data (2020), Environmental Impacts of Food Production: https://ourworldindata.org/environmental-impacts-of-food}

Various strategies can increase productivity and reduce emissions across agriculture and land use. The urgency of this is critical as these sectors must supply growing demands for food and resources. According to International Panel on Climate Change (IPCC), this is indeed possible while reducing emissions by up to 30% to limit global warming to 2°C or lower. 

Forestry

Maintaining forests is vital to ensure CO2 is sequestered from the atmosphere. Therefore, the agriculture and land use industry must continue to develop sustainably managed “working forests”. These can be used to produce wooden products that store CO2 even after the tree is cut.

Working forests can be sustainably managed by ensuring trees are replanted in the place of those cut down. Certain forest areas can also be maintained to protect biodiversity, and prevent nutrient run-off.  

Soils 

Carbon sequestration also happens within soil. Soil erosion, deforestation, and tillage/ploughing all release carbon from the soil. 

These harmful effects can be reduced by farming crops and pasture land among the trees, known as agroforestry. This also helps prevent further deforestation. 

Other methods include efficient crop/livestock rotation, as well as increasing crops which increases soil fertility, such as legumes. Productivity can also be increased through improved irrigation methods and organic fertilizers. 

Increasing crop yields at a sustainable rate involves new pest control and prevention methods. This reduces chemical pesticides use and prevents pollution as a result. 

Livestock 

Half of direct agriculture emissions come from livestock. Digestive processes in livestock release methane, a greenhouse gas, as a by-product into the atmosphere. Improving the digestibility of animal feed or methane-reducing supplements can help reduce these emissions. 

While these advances help to curb emissions from livestock, meat consumption worldwide continues to grow. This is especially the case for beef, which has the highest GHG emissions intensity per kilogram of food than any other food product. 

The production of beef also requires large amounts of vital resources- water, land and energy. Therefore, it’s important that public health policies and outreach campaigns push for reduced beef consumption. 

Nitrous oxide and methane can also be released from manure decomposing under low-oxygen conditions- such as in confined space where livestock is kept. Large piles of manure or dumping into waterways also creates soil and water pollution. Treating manure with anaerobic digesters can help mitigate these emissions.

According to IPPC, the agriculture and land use industries have been slow in implementing these strategies, and others like them. This is despite them costing relatively little to put into place. 

The IPPC has also criticised governments for not acting fast enough to oversee these changes and have called for governments to increase financial support into sustainable farming technologies, funded from redirecting non-climate related subsidies. 

5. Food Production

Food production, as we’re calling it, includes transportation, packaging, retailing, cooking and waste of food products. 

Reduced transport costs and improved efficiency across supply chains have made it easier to expand food supply chains internationally. As a result, ‘food miles’, which represent the fuel spent from transporting food products, continue to increase. 

Refrigerated products such as dairy, fruits and vegetables have 230% higher emissions of CO2e from non-refrigerated products. Therefore, such products tend to have the highest food miles. 

Typical food packaging such as glass, plastics or paperboard also use up a lot of resources like water, energy and petroleum. This production also creates a lot of GHG and CO2 emissions, as well as wastewater and toxic waste which go on to create pollution. 

Most packaging that’s produced will be discarded after use which has caused a massive, global waste issue, with catastrophic environmental impacts. 

Typically ending up in landfills, discarded packaging might take a long time to decompose, or never at all in the case of plastics. Instead, chemicals leach into the surrounding environment, polluting soils, water and the air.  

In fact, in our oceans, plastic pollution alone has been deemed a “planetary crisis” from within the United Nations. Plastic ends up in the oceans through drainage systems, especially from littering, or from illegal dumping. Between 1950-2017, 7 billion of the 9.2 billion tonnes of plastic produced ended up as waste, the UN reports. 

Decomposing plastic also sheds microplastics. This is often fatal for marine life and impacts fauna growth in the soils. Microplastics have also made their way into human diets, posing health risks from the various toxic chemicals that they absorb.

^{Our World in Data (2021), How much of global greenhouse gas emissions come from food?: https://ourworldindata.org/greenhouse-gas-emissions-food
Nature Food, Global food-miles account for nearly 20% of total food-systems emissions: https://www.nature.com/articles/s43016-022-00531-w.epdf?
Ocean Conservancy (2018), Fighting for Trash Free Seas: Ending the Flow of Trash at the Source: https://oceanconservancy.org/trash-free-seas/
UN Environment Programme (2021), UNEP Food Waste Index Report 2021: https://www.unep.org/resources/report/unep-food-waste-index-report-2021}

Food shortages, malnutrition, overexploitation of natural resources, and huge amounts of waste all point to an unbalanced and unsustainable food production industry.  

There are many approaches to improving the production and distribution of food. While prioritising locally sourced items is important, the mode of transport and its fuel efficiency must also be accounted for. 

For example, food items within Europe will travel less distance from those outside Europe. However, road transport has a higher emissions intensity than cargo ships meaning European food items might actually have more associated emissions. What’s more, production and retail can also be intensive processes that add to the environmental impact of products. 

To help combat this, manufacturers can get true insights into food products’ environmental impacts using life-cycle assessment (LCA) tools. These consider the entire lifecycle of a product and measure everything from release of toxins and GHGs to use of natural resources. Therefore, LCA’s enable industry stakeholders to make conscious decisions as to the impacts of their activities. 

Non-thermal preservation technologies, such as High Pressure Processing, have also become more accepted in food processing. Such technologies inactivate microorganisms that would usually degrade the quality of food. As such, food is preserved for longer. Compared to conventional preservation methods, non-thermal preservation uses far less energy during processing and storage since they are effective even in mild temperatures. It also addresses wider issues by reducing demand and preventing food losses. 

Industrial smart meters can be also deployed to reduce energy consumption during production. Given their economic benefits, the use of smart meters are becoming more widespread since they show the consumption rates of resources, such as water or electricity. This allows companies to strategise as to the best ways they can optimise productivity. 

Reducing waste 

New waste management techniques such as anaerobic digestion and biodegradation convert waste into bioenergy in the form of liquid or gas biofuels. 

It’s also important that plastic, and heavy emitting materials are replaced with wood, or paper based packaging, or aluminum for metal products. These materials can biodegrade faster, are easily recyclable and come from renewable sources (as long as the forests are managed sustainably). Alternative packaging can also derive from sources such as seaweed.

Plastics, made from polymers, can also continue to be produced from renewable sources. To prevent overexploitation of natural materials for packaging, widespread adoption of plastic recycling must also become more normalised. This also keeps plastics from becoming permanent waste. 

Conclusions

As you can see, within each polluting industry, multiple and far-reaching solutions must be put in place. Implementing new technologies, conserving natural resources, and limiting the use of toxic materials concerns many stakeholders- from producers to consumers.

There are glimmers across these industries of change, but rapid acceleration is needed to limit further warming, before there’s no going back.

In 2022, we’ve seen governments and industries respond with sanctions to Russia’s war in Ukraine. Because of this, global demand for fossil fuels will peak, or plateau in upcoming outlook scenarios, according to IEA. This shows us that it can be done quickly, and that a more secure, sustainable future may be in reach.