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Doctoral defence of Hasan Sohail, MSc, 6.5.2024: Epidemiological studies on the adverse health effects of non-optimum ambient temperatures

The doctoral dissertation in the field of Environmental Science will be examined at the Faculty of Science, Forestry and Technology, Kuopio Campus and online.

What is the topic of your doctoral research? Why is it important to study the topic?

The topic of my doctoral research is epidemiological studies on the adverse health effects of non-optimum ambient temperatures. Non-optimum temperatures have been ranked among the ten leading causes of death worldwide by the Global Burden of Diseases (GBD) 2019 study. Most of the previous studies have investigated temperature-associated mortality. However, the scientific evidence on the effects of non-optimum temperatures on morbidity is still scarce and has shown mixed results. Therefore, this topic of doctoral research is of paramount importance to understanding temperature-associated morbidity.

What are the key findings or observations of your doctoral research?

Single days with high temperatures during summer months pose fewer health risks than heatwaves concerning cardiovascular and respiratory admissions in the Northern climate. Exposure to heatwaves can increase the risk of hospitalization for pneumonia, total respiratory diseases, COPD (Chronic Obstructive Pulmonary Disease), cerebrovascular, and MI (Myocardial Infarction).

Heatwave-associated morbidity may vary depending on the duration and intensity of the hot period and can affect people from all age groups. Low winter temperatures can also increase the risk of hospitalizations for MI, total respiratory diseases, and COPD. Cold spells can increase the risk of asthma hospitalizations.

Short-term exposure to non-optimum temperatures can cause adverse health effects among individuals across all age groups, not just among the elderly. 

How can the results of your doctoral research be utilized in practice?

Public health officials can make prevention plans based on scientific evidence provided by our research. Moreover, awareness campaigns should be organized to provide people with an understanding of the impacts of non-optimum temperatures on human health.

What are the key research methods and materials used in your doctoral research?

My doctoral research is based on three article-based publications. For the first paper, multivariate Poisson time series regression models were used to evaluate the association of the daily number of hospital admissions with daily mean temperature and heatwaves during the summer months. For the second paper, we used a quasi-Poisson regression with distributed lag nonlinear models (DLNM) to investigate the lagged and cumulative effects of daily mean temperature and cold spells on the daily number of hospital admissions in the colder months. For the third paper, DLNM, linear regression, and logistic regression models were used to assess the association of self-rated health with daily ambient temperature during the summer and winter months.

Is there something else about your doctoral dissertation you would like to share in the press release?

My doctoral dissertation investigates the association of non-optimum ambient temperature with health outcomes. The ambient temperatures are indeed a public health threat for individuals from all age groups.

The doctoral dissertation of Hasan Sohail, MSc, entitled Epidemiological studies on the adverse health effects of non-optimum ambient temperatures will be examined at the Faculty of Science, Forestry and Technology, Kuopio Campus. The opponent will be Professor Janine Wichmann, University of Pretoria, South Africa, and the custos will be Professor Timo Lanki, University of Eastern Finland. Language of the public defence is English.

For more information, please contact: 

Hasan Sohail,, p. +358 413 142 072,