On Iran's National Tree Planting Day, the World Health Organization (WHO) country office in Tehran took a symbolic step towards environmental improvement, planting trees amidst the city's severe air pollution challenges. The initiative highlights the critical need for environmental action in a city grappling with hazardous air quality.

Tehran, a sprawling metropolis nestled among mountains, suffers from trapped air pollutants, exacerbated by winter temperature inversions. The city's high elevation (1,200–1,800 meters above sea level) contributes to lower oxygen levels, resulting in incomplete fuel combustion and increased emissions. Alarming data reveals that in the 2023-2024 period, fine particulate matter (PM2.5) levels fell within WHO air quality guidelines only on a mere 3.2% of days.

PM2.5, a dangerous pollutant, penetrates deep into the lungs and enters the bloodstream, impacting major organs. Exposure is linked to severe health issues, including stroke, lung cancer, and chronic obstructive pulmonary disease (COPD). Emerging research also suggests a connection between prenatal exposure to high levels of air pollution and developmental delays in children, as well as later psychological and behavioral problems like ADHD, anxiety, and depression.