What is Transboundary Air Pollution?

Global and cross-national efforts to reduce pollution emissions and safeguard good air quality have expanded rapidly in recent years. Groups such as the World Health Organization and various national governments have pledged to these goals. Many of these initiatives, including the United States’ Clean Air Act, have worked to facilitate cleaner air and have improved the quality of life for many people.

However, these policies and pledges haven’t been adopted by every nation in the world. In fact, even among those nations pushing for cleaner air, only seven met the WHO guidelines in 2024. This means that whether you live in a nation striving for cleaner air or not, you could still be subject to Transboundary Air Pollution.

What is Transboundary Air Pollution?

Have you ever sat outside on a warm but breezy day in summer only to get hit with the smell of a lit cigarette or your neighbor’s grill? While one of those might be more pleasurable than the other, they still both originated outside of your property. This is essentially the idea behind transboundary air pollution. As the US EPA puts it, “air pollution does not stop at national borders… transboundary flows of pollutants occur between the United States and our closest neighbors, Mexico and Canada.”

Air pollution created in one place doesn’t have to, and often won’t, stay in that place. Just like how your neighbor’s smoking habit affects your air quality, air pollution on an international scale transcends borders and ends up somewhere different than where it's from.

Has Air Pollution Always Been a Problem?

Air pollution has long been identified as a threat to human health. In “A chronology of global air quality,” a study published in Philosophical Transactions of the Royal Society A: Mathematical, Physical, and Engineering Sciences, authors David Fowler et al. explore the history of air pollution and its associated effects. They state that numerous written accounts identify air pollution, in one way or another, as far back as Hippocrates' time, ca 400 BC. However, true exploration of the issue didn’t begin until much later.

While more localized sources of air pollution, such as forest fires or temperature inversions, have occurred throughout human history, the Industrial Revolution is largely what led to the proliferation of air pollution. As identified by Fowler et al., “industrial development and rapidly increasing emissions from short stacks” as well as an “urban population of factory workers who mostly burned coal for warmth and cooking” contributed heavily to the spread of air pollution. Of course, industrialization, and with it, this growth in air pollution, continued largely uninhibited until 1952, when the UK experienced what we now call the Great Smog of London, a grueling five-day-long weather event that resulted in the “premature mortality of approximately 12,000 people.” Ultimately, this was enough to change minds about air pollution, and the UK’s first Clean Air Act was passed a few years later in 1956.

Over the following decades, more and more nations passed similar legislation to protect the health of their citizens, and the result is where we are today. It was also during this time that the idea of transboundary air pollution began to crop up. Fowler et al. recognize that even as early as the 1950s, some people theorized that air pollution could be transported over large distances and cross national borders. However, it didn’t really become a major concern until the late 1960s and 1970s.

Transboundary Air Pollution in the Modern Day

Today, air quality has improved in many parts of the world. However, because heavy pollution sources may not be a concern in your immediate area, transboundary air pollution becomes much more relevant. A study on particulate matter PM levels in Ho Chi Minh City, Vietnam, for example, found that air pollution increased dramatically during two separate transboundary events because of anthropogenic pollution from China and biomass burning in India. Due to the city’s geographical location, it is a hotspot for drifting pollution. Even though sources in the city itself were not the cause, residents of Ho Chi Minh still suffered.

Though it is impossible for an individual to combat these issues alone, there are many things you can do to protect yourself and your family. Learn More Here