A large number of infectious diseases are transmitted by respiratory droplets. How long these droplets persist in the air, how far they can travel, and how long the pathogens they might carry survive are all decisive factors for the spread of droplet-borne diseases. The subject is extremely multifaceted and its aspects range across different disciplines, yet most of them have only seldom been considered in the physics community. In this review, we discuss the physical principles that govern the fate of respiratory droplets and any viruses trapped inside them, with a focus on the role of relative humidity. Importantly, low relative humidity-as encountered, for instance, indoors during winter and inside aircraft-facilitates evaporation and keeps even initially large droplets suspended in air as aerosol for extended periods of time. What is more, relative humidity affects the stability of viruses in aerosol through several physical mechanisms such as efflorescence and inactivation at the air-water interface, whose role in virus inactivation nonetheless remains poorly understood. Elucidating the role of relative humidity in the droplet spread of disease would permit us to design preventive measures that could aid in reducing the chance of transmission, particularly in indoor environment.
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http://dx.doi.org/10.1007/s10867-020-09562-5 | DOI Listing |
Heliyon
January 2025
School of Architecture, Tianjin University, 300072, Tianjin, China.
Air pollution has become a major challenge to global urban sustainable development, necessitating urgent solutions. Meteorological variables are key determinants of air quality; however, research on their impact across different urban gradients remains limited, and their mechanisms are largely unexplored. This study investigates the dynamic effects of meteorological variables on air quality under varying levels of urbanization using Kaohsiung City, Taiwan, as a case study.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Southern University of Science and Technology, Department of Mechanical and Energy Engineering, 1088 Xueyuan Blvd, Nanshan District, 518055, Shenzhen, CHINA.
The escape of organic cations over time from defective perovskite interface leads to non-stoichiometric terminals, significantly affecting the stability of perovskite solar cells (PSCs). How to stabilize the interface composition under environmental stress remains a grand challenge. To address this issue, we utilize thiol-functionalized particles as a "seed" and conduct in situ polymerization of 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFMA) as a "root" at the bottom of the perovskite layer.
View Article and Find Full Text PDFBMC Public Health
January 2025
Key Laboratory of Cities Mitigation and Adaptation to Climate Change in Shanghai (CMACC), Shanghai, 200092, China.
Background: Due to climate change and rapid urbanization, the frequency of heatwave events in East China has increased considerably since the 21st century, which has a considerable influence on human health, such as heatstroke. However, few studies have been conducted in this region on the relationship between heatstroke and meteorological conditions. To address this point, this study aimed to analyze the characteristics of heatstroke and their relationship with meteorological conditions in Hefei, China.
View Article and Find Full Text PDFEur J Appl Physiol
January 2025
Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, 125 University, Montpetit Hall, Room 367, Ottawa, ON, Canada.
Sleep deprivation has been associated with impaired thermoregulatory function. However, whether these impairments translate to changes in whole-body heat exchange during exercise-heat stress remains unknown. Therefore, following either a night of normal sleep or 24 h of sleep deprivation, 10 young men (mean (SD): 23 (3) years) completed three 30-min bouts of semi-recumbent cycling at increasing fixed rates of metabolic heat production (150, 200, 250 W/m), each separated by a 15-min rest in dry heat (40 °C, ~ 13% relative humidity).
View Article and Find Full Text PDFJ Hazard Mater
January 2025
Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India.
Experiments were conducted in controlled laboratory conditions to determine the size-resolved CCN (Cloud Condensation Nuclei) activity of sub micrometer-sized aerosols containing nuclear fission products (CsI and CsOH) and abundant ambient inorganic aerosols ammonium sulphates ((NH)SO), ammonium chloride (NHCl), sodium nitrate (NaNO), and sodium chloride (NaCl). The presence of these atmospheric-relevant compounds internally mixed with fission product compounds has the potential to affect the capacity of ambient particulates of aerosols to absorb water and function as CCN. Once in the atmosphere, the dynamics of airborne radionuclides and subsequently their fate gets affected by dry and wet deposition processes.
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