On certain mornings, people see sunlight filtering through the haze in the air that forms a straight shining line. Though the scene appears peaceful and warm, the air carries millions of invisible particles — tiny fragments of dust, smoke, and microscopic life — that quietly shape the air we breathe. This raises the question: What is in the air we breathe?
Tracing back to at least 2,400 years ago, Hippocrates, the author of Airs, Waters, and Places, addressed that all kinds of illness are related to impure air quality, and he was not entirely wrong. After this, it was not until the Great Smog of London that people eventually recognized this as a catastrophic and concerning issue, following the deaths of 12,000 people. In contemporary society, air quality problems have been elevated to a novel level due to industrialization, modernization, and climate change resulting from black exhaust emissions of factories and waste gases from cars. Today, air pollution remains a global health crisis. According to a 2022 study in Environmental Science & Technology, it caused about 6.7 million premature deaths worldwide in 2019, making it the fourth leading cause of early death, after high blood pressure, tobacco use, and poor diet.
To further address this question, it is indispensable to understand the key terms that define it. At the beginning, air pollution is a mix of gases and microscopic particles that enter the atmosphere from natural sources and human activity. Among the most harmful are particulate matter — tiny solids known as PM2.5, which are small enough to pass deep into the lungs — and gases like nitrogen dioxide and ozone. According to researchers, there are no “safe levels” of PM2.5. In fact, even low concentrations can increase the risk of respiratory and cardiovascular disease. Moreover, these particles are pervasive—they are capable of spreading quickly and far. As scientists continue to uncover new links between air quality and health, it becomes clear that what we breathe affects much more than our lungs.
Now, it is time to illustrate the impact of air quality on daily life. First of all, the most concerning issues affecting everyone are allergies, asthma, coughing, fatigue, and headaches. Scientists now understand that fine particles can enter the bloodstream, affecting nearly every organ. Eventually, the body transits into a sub-healthy state, defined by a decline in physical, psychological, or social well-being. Living in a location struck with massive air pollution not only causes the listed health concerns but also damages health in the long term, including heart, lung, and cognitive diseases. For example, in the summer of 2023, smoke from Canadian wildfires caused poor air quality across many Massachusetts regions, including Concord, leading to health concerns and alerts. People reported that sensitive groups were affected with symptoms such as coughing.
Finally, after defining air pollution and its effects, we arrive at the question: How can we improve air quality? Actually, choosing to walk, bike, or carpool helps reduce vehicle emissions, one of the biggest sources of air pollutants. On a larger scale, supporting cleaner energy policies and paying attention to air quality alerts can make our collective impact stronger. Even small changes, such as turning off engines while waiting, opening windows for ventilation, or simply being aware of local air quality, add up over time.
Air quality is not an ignorable thing, even though it is invisible. It is a responsibility carried by every human being who lives on the planet and breathes. Raising awareness is the first step toward change: the more we learn about air quality, the more we can do—and the better our breathing can feel.