A recent exploration of air quality trends across various high and middle-income countries reveals that the West is breathing cleaner air than perhaps at any point since urbanization began. This trend suggests that developing nations may not need a century or more to achieve similar improvements. The findings highlight the significant reduction in sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions, two key pollutants from industrial activity.

Sulfur Dioxide and Nitrogen Oxide Emissions

SO2 and NOx are primarily emitted from the burning of fossil fuels, particularly coal, and from internal combustion engines. These pollutants are responsible for millions of lost life years worldwide due to respiratory problems, cardiovascular issues, and neurological diseases exacerbated by prolonged exposure.

Historical Context and Current Trends

Historically, urban environments in the West were heavily polluted due to emissions from wood smoke and coal burning. However, significant reductions in coal use have dramatically improved air quality. For instance, the UK’s sulfur dioxide emissions have dipped below levels seen during the earliest periods of British industrialization, marking a significant improvement in air quality over the past few centuries.

Technological Solutions and Policy Interventions

Technological advancements and policy interventions have been crucial in reducing SO2 emissions. The UK’s reduction in coal consumption and the implementation of scrubbers in coal-burning power plants have played a pivotal role. For example, the US included a cap-and-trade scheme on SO2 as part of its Clean Air Act Amendments in 1990. This policy forced coal plants to either implement technologies to reduce emissions, trade credits with other plants, or pay hefty fines for excess sulfur emissions. Over a single decade, emissions dropped by double-digit percentages.

“In 1990, the US included a cap-and-trade scheme on SO2 as part of its Clean Air Act Amendments. Each coal plant was given a ‘cap’ for how much SO2 it could emit, forcing it to either implement technologies to reduce its emissions, trade credits with other plants, or pay a large fine for every tonne of extra sulfur it emitted.”

Scrubbers, large towers where aqueous mixtures of lime or limestone absorbers are sprayed through the emissions, have been particularly effective. China, despite tripling its coal use since 2000, has managed to reduce SO2 emissions to pre-2000 levels by implementing these technologies. In contrast, India, which does not use or mandate coal scrubbers, has seen an upward trajectory in both coal use and emissions.

Health Implications and Alternative Fuels

It is important to note that burning coal, while harmful, is often preferable to burning wood or dung, which produce more significant health hazards. Particulate matter in wood smoke is much larger and more harmful than smoke from fossil fuels. Air quality in cities improves when switching from wood and dung to coal, and further improves with the transition from coal to natural gas. More years of life are lost due to lack of electricity compared to coal-powered electricity.

Nitrogen Oxide Emissions from Transportation

NOx emissions, generated from the burning of gasoline, diesel, and kerosene in internal combustion engines, have shown a gradual upward trend throughout the 20th century. However, the UK’s NOx emissions have fallen to levels seen in 1950, despite a significant increase in road-driven miles. This improvement is largely due to increased fuel efficiency and exhaust systems on automobiles mandated by the EU in the 1990s. The Euro 1 rating, introduced in 1992, has evolved to Euro 6, leading to significant reductions in NOx emissions.

“To comply with regulations, car manufacturers have had to innovate on technologies that can reduce the emissions of NOx and other pollutants from car exhausts. These technologies have included catalytic converters, filters for particulate matter, gas recirculation—which lowers the temperature of combustion and therefore produces less NOx from the exhaust…”

Hannah Ritchie

Countries like South Africa, Brazil, and China have adopted similar emissions standards, demonstrating how quickly harmful emissions can be reduced with smart regulation. Beijing, once notorious for its air pollution, now enjoys clear skies due to a “war on pollution” that increased average life expectancy by four years.

Future Prospects and Policy Recommendations

The success stories of the West and China offer valuable lessons for other developing nations. Implementing cap-and-trade schemes, mandating the use of scrubbers, and promoting fuel-efficient technologies can significantly improve air quality. Additionally, transitioning from coal to cleaner energy sources like natural gas and renewable energy can further reduce emissions. Policymakers should prioritize these interventions to ensure a healthier future for all.