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Background and purpose: Tuberculosis (TB) is one of the main medical and health problems worldwide. Herein, we aimed to evaluate the effect of environmental factors on the incidence of this disease. In so doing, we can determine the critical and deficient areas, the risk factors for the disease, and implement preventive and therapeutic interventions.

Materials and methods: In this retrospective, descriptive-analytic study we used available information in health centers in Mashhad, Iran. Personal, demographic, environmental, and geographic data was the main basis of our study to identify the high-risk areas.

Results: We studied 813 patients diagnosed with TB in Mashhad health centers of Mashhad and its outskirts. The results showed significant relationship between the developing TB and nationality (P<0.05). Also, there was an association between risk of developing TB and living near major traffic arteries, areas with livestock farms or without waste collection system (P<0.05). The city's outskirts were determined as critical areas that need further considerations by health authorities.

Conclusion: Given the increasing incidence rate of TB in Iran, particularly in Mashhad, and escalated TB mortality, identifying factors causing the disease, especially the environmental and demographic factors, can improve management of this disease.

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Background and purpose: Asthma is a chronic inflammatory disease of the airways that is caused by hypersensitivity to environmental allergens. Symptoms of asthma include shortness of breath, airway hyper-responsiveness, wheezing, and cough. The disease might vary from a mild to severe and intermittent to chronic disease. Asthma is known as a multifactorial disease due to the interaction of genetic and environmental factors in its development. Identifying the environmental and genetic factors are of great benefit for prevention, diagnosis and treatment of allergic asthma. The aim of this review was to investigate the factors that increase the risk of asthma.
Materials and methods: Electronic databases including Scopus, PubMed, Google Scholar, Scientific Information Database (SID), Magiran, and Irandoc were searched for relevant articles published between 1990 and 2016. The search keywords were asthma, atopy, genetic factors, polymorphisms, environmental factors, and gene-environment interaction.
Results: This review showed that asthma is a complex and multifactorial disease and the combination and interaction of environmental and genetic factors have a role in its development and progression. Therefore, each of these factors cannot be considered as an absolute cause of asthma, but a set of factors such as genes influencing inflammatory pathways, airway rebuilding, and environmental factors should be considered as risk factors.
Conclusion: Asthma is a complex and multifactorial disease and interaction of several genetic and environmental factors are involved in its clinical presentation. A major step in determining the genetic causes of asthma is identifying chromosomal regions and candidate genes associated with asthma.

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 Background and purpose: Environmental factors can play a role in incidence, infection, and mortality rates of Coronavirus disease (COVID-19). In this study, we performed a systematic review of environmental factors affecting the incidence, infection, and mortality rates of COVID-19.
Materials and methods: In this review, articles, case studies, and official reports were searched in electronic databases, including PubMed, Scopus, Web of Science, Google Scholar, Magiran, and Scientific Information Database (SID)  using the following keywords: COVID-19, Environmental factors, Air pollution, Temperature and humidity, Water and wastewater, and Coronavirus. Studies on the relationship between environmental factors affecting infection and mortality rates of COVID-19 published until July 2021 were selected. Qualitative evaluation of articles was performed using the STROBE checklist.
Results: Out of 62 articles found 30 were reviewed. Air pollution, temperature, humidity, water, wastewater, and waste could play a role in incidence, infection, and mortality rates of COVID-19. Environmental control was found to be effective in preventing the spread of infection and reducing the mortality rate of COVID-19. Improving environmental performance could be of great benefit in preventing the spread of many diseases, particularly the COVID-19 pandemic.  
Conclusion: Ensuring global environmental performance is essential to protect all countries against COVID-19 and other public health hazards. Meanwhile, more investment in research and development is needed.

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Background and purpose: Considering the effects of dengue fever on the health of people in the society and the role of climatic and environmental factors on the spread of this disease, this review study has investigated the climatic and environmental factors affecting the prevalence of dengue fever.
Materials and methods: In this review, the academic papers, in English and persian languages, published until the beginning of August 2022 were investigated. These articles were searched in scientific databasese of Scopus, ScienceDirect, PubMed, Web of Science and Google Scholar, using keywords such as "dengue fever", "dengue vector", "vector mosquito", "Aedes mosquito", "environmental factors", and "weather factors". Endnote X8 software was also used to organize, and study titles and abstracts of the articles.
Results: Considering the impacts of environmental changes on mosquito population and its subsequent effect on the occurrence of dengue fever, the present study showed that changes in climatic factors including air temperature, rainfall, and humidity affect the frequency of dengue disease vectors. Land use and land cover change can affect mosquito population and dengue transmission by changing local ecology. Household waste and its accumulation around residential houses can also hold a significant amount of water as environmental pollutants and can be considered as a habitat for mosquito larvae such as Aedes species.
Conclusion: The analysis of climatic and environmental factors has shown that environmental factors and weather changes can affect the occurrence of dengue fever.