Health impact and related cost of ambient air pollution in Tehran.

Ambient air pollution represents one of the biggest environmental risks to health. In this study, we estimated the avoidable mortality burden attributable to ambient air pollution in Tehran, and derived the economic impact associated with these health effects. Using PM2.5 data from ground-level air pollution measurements in Tehran, we estimated PM2.5 exposure for 349 neighborhoods in Tehran, by the Environmental Benefits Mapping and Analysis Program (BenMAP-CE). We considered five scenarios related to PM2.5 levels: an increase to 35 μg/m3; a reduction to 25 μg/m3; a reduction to 15 μg/m3; a reduction to 10 μg/m3 (the WHO's air quality guideline value); and a full roll-back, assuming a reduction to 2.4 μg/m3. All scenarios used 2017 p.m.2.5 levels as a starting point. Using the concentration response function of the Global Exposure Mortality Model (GEMM), we estimated a total of 7146 (95% CI: 6596-7513) adult (age ≥25 years) deaths attributable to PM2.5 in 2017. The leading causes of death were ischemic heart disease (3437; 95% CI: 3315-3516), stroke (886; 95% CI: 693-1002), lower respiratory infections (531: 95% CI: 414-589), chronic obstructive pulmonary disease (364; 95% CI: 271-420), and lung cancer (274; 95% CI: 236-298). The estimated total annual economic benefit (2017) of reducing PM2.5 concentration levels to 2.4 μg/m3 was USD 0.591 (95% CI: 0.447-0.624) billion per year, using the value of a life year (VOLY) approach, and USD 2.894 (95% CI: 2.671-3.043) billion per year, using the value of a statistical life (VSL) approach.