Assessing the short-term hematological and pulmonary effects of air pollution: a cross-sectional study in a Turkish urban setting | BMC Public Health

This study investigates the relationship between the AQI and hemogram as well as PFT parameters in a healthy population. Our findings revealed a significant association between AQI and hematological parameters, specifically leukocyte, platelet, and lymphocyte counts, while no significant correlation was observed with PFT parameters.

The majority of the study days (63.2%) had AQI values between 51 and 100, categorizing air quality as “moderate”. This suggests that, while air pollution in the study region does not frequently reach hazardous levels, it may still pose health risks, particularly to sensitive groups. According to the 2016 “Assessment Report on Turkey’s Environmental Issues and Priorities,” published by the Ministry of Environment and Urbanization, Erzincan, the province where this study was conducted, is among the regions with high PM10 levels, especially during the winter months [14]. The primary contributors to this issue include the widespread use of coal for heating, increased vehicular emissions, industrial activities, and meteorological conditions that trap pollutants in the atmosphere.

The significant findings related to hematological parameters, particularly the negative correlations between AQI and leukocyte, platelet, and lymphocyte counts, suggest that air pollution may be influencing immune system activity. Leukocytes are a critical component of the immune system, with their levels often reflecting inflammation or infection. Lymphocytes, a subtype of leukocytes, play a key role in adaptive immunity, particularly in response to viral infections and chronic inflammation. The observed changes in these parameters may reflect the immune system’s response to environmental stressors, such as air pollution. This aligns with several studies in the literature that have explored the effects of air pollution on blood parameters [16, 17]. For instance, Rich et al. reported a decrease in leukocyte counts in healthy young adults following prolonged exposure to air pollution during the Beijing Olympics [17]. Similarly, Riediker et al. found that repeated exposure to air pollutants increased leukocyte counts while decreasing lymphocyte levels, indicating a complex relationship between air pollution and immune function [18].

The observed alterations in hematological parameters may be attributed to several biological mechanisms induced by air pollution. Exposure to PM10 and NO2 has been shown to generate reactive oxygen species (ROS), leading to oxidative stress and triggering systemic inflammation [19]. This process can result in the release of pro-inflammatory cytokines, which in turn affects the production and turnover of immune cells, such as leukocytes, lymphocytes, and platelets [20, 21]. The negative correlations observed between AQI and leukocyte or lymphocyte counts might reflect a suppression of immune activity due to oxidative stress or a compensatory mechanism in response to chronic low-level inflammation. This suppression could potentially reduce immune system responsiveness in the face of prolonged air pollution exposure. Additionally, air pollution has been linked to endothelial dysfunction, which can further stimulate the immune system and promote the release of platelets and leukocytes into circulation, contributing to the hematological changes observed in this study [22]. The lack of consensus regarding the effects of air pollution on blood cells in different studies could be explained by varying pollutant compositions (PM10, CO, SO2, NO2, O3), exposure durations (acute vs. chronic), and population characteristics. For example, Poursafa et al. observed positive correlations between air pollution and leukocyte/platelet counts in children, suggesting that age and baseline health may influence these outcomes [9].

Our study highlights significant correlations between air AQI and PFT parameters, including FEV1%, FVC%, and FEF values, emphasizing the detrimental effects of air pollution on lung function, even in a healthy population. The observed reductions in PFT indices with increasing AQI values, particularly the 5-day averages, support prior findings that associate particulate matter (PM2.5) and nitrogen dioxide (NO2) with inflammatory and oxidative stress responses in the respiratory system [23]. These results underscore the short-term impact of air pollution exposure on pulmonary performance, even among individuals without pre-existing respiratory conditions.

Notably, small airway function markers, such as FEF50% and FEF75%, exhibited particularly strong correlations with higher AQI levels. This finding aligns with recent studies demonstrating the vulnerability of small airways to fine and ultrafine particulate exposure, including PM0.1 from biomass burning and urban pollution [24,25,26]. Such particles are known to penetrate deeply into the lung tissue, leading to localized inflammation and impairments in airflow. The sensitivity of FEF values to air pollution highlights their potential utility in early detection of respiratory effects in populations exposed to moderate levels of pollution [27]. These findings emphasize the need for proactive monitoring and longitudinal studies to assess the cumulative effects of chronic air pollution exposure on both pulmonary and systemic health outcomes.