This study was conducted in Karaj city, Iran, to examine the effects of particulate matter (PM10) air pollution on human health, specifically respiratory and cardiovascular diseases. Its objective was to predict the medical conditions requiring treatment. The study observed a declining trend in PM10 concentrations from 2017 to 2019, followed by an increase from 2019 to 2021. Other findings indicated that every 10 µg/m3 increase in PM10 concentration reduced the risk of respiratory-related hospital admissions by 0.8% and cardiovascular disease admissions by 0.9%. Over the past six years, there were 3,686 respiratory disease hospitalizations and 1,606 cardiovascular disease hospitalizations. Surprisingly, contrary to our predictions, the number of hospitalizations for respiratory and cardiovascular conditions decreased despite the increased levels of PM10 exposure in recent years.
In another study conducted by Rezaei Kalantari et al., which evaluated the health effects of exposure to airborne particulate matter in Tehran from 2004 to 2015, the total number of hospitalizations due to cardiovascular disease was 20,990, and due to respiratory disease, it was 54,352 cases, both of which were attributed to PM10. The study concluded that exposure to suspended particles in Tehran had severe health effects, leading to increased mortality and cardiovascular and respiratory diseases among its citizens (Rezaei Kalantari R, 2018).
Similarly, in Urmia, the estimated number of hospital admissions attributed to PM10 indicated unfavorable conditions in the city. This could be due to either prolonged periods of high concentration of suspended particles or a higher overall mean of this pollutant (Sokoty L, 2020).
According to a study by Naghan DJ (2022), the death rates attributed to PM2.5 were 176 for ischemic heart disease (IHD), 7 for chronic obstructive pulmonary disease (COPD), 0 for lung cancer, 10 for acute lower respiratory infection (ALRI), and 105 for stroke. It was found that particulate matter, especially PM2.5, had negative effects on human health even at low concentrations, and these effects were associated with respiratory morbidity and mortality (Asl FB, 2018).
In Shiraz, the highest health impacts attributed to air pollutants were due to PM10 pollution. The harmful effects of PM10 significantly increased when concentrations exceeded 40 µg/m3. The study revealed that in 2019, the number of deaths attributed to PM10-related respiratory and cardiovascular diseases in Shiraz was 92 and 22, respectively, accounting for 2.4% of the total deaths in the city. It can be concluded that failure to manage particulate matter pollution can lead to more deaths and other health effects (Bonyadi Z, Arfaeinia H, 2020). The results also indicate that the hospitalization rate attributed to PM10 decreased over time from 2017 to 2021.
In Tehran, the neighboring province, the study showed that the largest health effects were associated with suspended particles (PM) with aerodynamic diameters of 2.5 and 10 micrometers (Hoseini M, 2017). However, in the present study in Karaj, the health effects attributed to PM10 from 2016to 2021 had a smaller contribution to the hospitalization rate as time passed.
Overall, using this software to estimate the number of people hospitalized for cardiovascular and respiratory diseases in the years studied clearly demonstrates the impact of suspended particles on the health of Karaj residents. However, it is important to note that the health effects attributed to PM10 from 2016 to 2021 contributed less to the hospitalization rates over time. This generalization may not always hold true and may represent a broad overview. Additionally, population exposure to pollutants depends on various factors such as individual breathing habits, age, diet, existing or genetic diseases, social and economic status, as well as internal and external activities, and occupational exposure.
One major limitation of this study is its ecological nature, which prevents controlling for potentially influential factors at an individual level, such as those related to breathing habits, age, diet, existing or genetic diseases, social and economic status, etc. Furthermore, the study utilized the AirQ model to assess the short-term impact of PM10 exposure. It is important to mention that no model can estimate the effects of all pollutants simultaneously. However, the AirQ model is one of the most promising models recommended by the World Health Organization (WHO) for assessing the health effects of air pollutants.