Lung cancer remains one of the most common and deadly forms of cancer worldwide, traditionally associated with long-term tobacco smoking. However, recent trends have shown a concerning rise in lung cancer diagnoses among individuals who have never smoked in their lives.

A new medical study conducted by researchers at the University of Southern California (USC) has offered an unexpected explanation for this shift, challenging long-held assumptions about the disease’s primary causes.

According to the findings, lung cancer in non-smokers is increasingly linked to a combination of environmental, genetic, and lifestyle-related factors rather than tobacco exposure alone. Researchers suggest that long-term exposure to air pollution, particularly fine particulate matter (PM2.5), may play a significant role in damaging lung tissue over time.

The study highlights that urban air pollution, industrial emissions, and vehicle exhaust are major contributors to microscopic lung damage, which can eventually trigger cancerous changes in cells. In densely populated cities with high pollution levels, even individuals who have never smoked may face elevated risks.

In addition to environmental factors, the research points to genetic mutations that can develop spontaneously or be inherited, making certain individuals more vulnerable to lung cancer regardless of lifestyle choices. These genetic changes may interact with environmental pollutants, further increasing the risk.

Scientists involved in the study emphasized that the traditional view of lung cancer as primarily a smoker’s disease is no longer sufficient to explain current global trends. They argue that a broader approach is needed to understand and address the rising number of cases among non-smokers.

The researchers also noted that hormonal factors, previous lung infections, and exposure to secondhand smoke—even in small amounts—may contribute to long-term risk, although these were not the primary focus of the study.

Public health experts say the findings underscore the importance of air quality regulation and environmental protection measures. Reducing pollution levels could play a crucial role in preventing not only respiratory diseases but also certain types of cancer.