Investigating the association between Ambient Air Quality, Heat Index, and Incidence of Acute cardiovascular disease (MI) in Qatar

Abstract

Introduction: Over the last decades, air pollution impacts on the environment and human health has been continuously increasing. Air pollution is the primary cause of deaths for almost 7 million per year worldwide. Over the past years, Qatar has been experiencing a rapid industrialization and urbanization that have caused increased emissions in the country. The primary causes of emissions are fossil fuel burning, which are also the main source of income, energy consumption and transportation. All these factors led to deterioration of the air quality in the country, leading to environmental and human health impacts and more specifically to cardiovascular diseases. In this study, we aimed to investigate the association between air quality, heat index and the incidence of myocardial infarction (MI). At the same time, we aimed determine the impact of traffic on PM 2.5 level and its composition in heavy metals. Methodology: In this study, we used a quantitative method to analyze air quality components and hospital admissions data. Air quality and meteorological data were collected from an air quality monitoring station located in an urban area and under the supervision of Qatar Environmental and Engineering Institute, while MI admissions data were obtained from HMC heart hospital. The study focused on criteria air pollutants: PM 2.5, NO2, O3, SO2 and CO. The obtained data was from June 2018 to December 2024. Descriptive statistical analysis, yearly, monthly, daily, seasonal variation and correlation was done using regression models and Pearson’s correlation matrix for both air pollution data and health data. A time stratified case crossover design was used to assess the relative risk associated with the exposure to selected air pollutants, heat index individually and in combination and acute myocardial infarction hospital admission. Furthermore, a measurement of PM2.5 levels using gravimetric method was done for two different urban areas, and the composition in selected heavy metals of PM2.5 collected on the filter papers was determined using ICP-MS. Only the heavy metals that were reported in the literature to be associated with cardiovascular toxicity were considered. Results: The study findings indicated that PM 2.5, O3 and CO reached their peak levels during the hot and humid season. However, NO2 is more concentrated in the atmosphere during the cold season. The overall mean PM 2.5 concentration was 36.65 ± 27.22 μg/m3, with peak value exceeding 100 μg/m3 in August, while the overall NO2 mean value was 27.05±16.66 ppb, with the peak value recorded in June (80 ppb). Ozone levels followed a clear seasonal pattern with an overall mean concentration of 33.47±21.61 ppb but reaching 115 ppb in June. CO and SO2 showed more stable values over the study period. The overall mean level for the heat index was 31.17±9.77, reaching 69.48 during the hot and humid season. The total number of patients included in the study was 16051 patients. 91% were male patients versus 9% only females, with an overall average age of 52 years. 40 % of patients admitted for myocardial infarction had two or more comorbidities, while 23 % did not have any associated comorbidities. The regression analysis revealed the existence of a significant relationship between air pollutants, meteorological factors and the daily MI admissions in the heart hospital. The relative risk of MI admissions increases by 1.01 with every increase in PM 2.5 by 10 μg/m3 and by 1.018 with every NO2 increase by 10 ppb, and by 1.02 at lag 2 with every O3 increase by 10 ppb. Interestingly, the study showed that females and young group (≤50 years) are more prone to develop acute MI when exposed to these environmental factors, compared to male and elderly (above 50) groups (RR 1.024 for females’ vs 0.982 for males for O3 and heat exposure, and 1.010 for young vs 0.999 for elderly for PM 2.5 and heat exposure) . On the other hand, people with 2 or more comorbidities are more vulnerable to these pollutants and at higher risk of developing MI (RR 1.10 for those with 2 or more comorbidities and 0.998 for those without comorbidities, both for PM 2.5 and heat exposure). The collected and analysed air samples showed that the PM 2.5 heavy metals composition is different from low traffic versus high traffic areas with significant difference between heavy metals composition (p<0.05). Results also showed that the composition during weekdays and weekends are non-identical, however the difference between heavy metals concentrations were not significant (p=0.27). Conclusion: This research suggested that some air pollutants and heat stress have significant impacts on cardiovascular health at the population level. Furthermore, it also suggested that among the population vulnerable groups there are more to suffer from this impact. It is necessary therefore to call for action by stakeholders to act and limit air pollutants emissions, limiting the exposure by raising awareness among vulnerable populations to these environmental hazards. Future studies should investigate the effects of air pollutants on other body systems such as neurological and respiratory systems, to depict a clear picture of the impact of environmental factors on humans and ecosystems.