Airborne Causes of Disease

The changes in humidity levels during the Diwali festivities have been examined over a period of 13 years at three Indian metro cities: Ahmedabad, New Delhi and Kolkata. A small short term increase in relative humidity even in the absence of transport ...

****"One of the standard rules (Stoke’s Law) applied in engineering calculations to estimate the suspension times of droplets falling under gravity with air resistance, was derived assuming several conditions including that the ambient air is still. So actual suspension times will differ and vary." "Although short-range large-droplet transmission is possible for most respiratory infectious agents, deciding on whether the same agent is also airborne has a potentially huge impact on the types (and costs) of infection control interventions that are required." "Despite the various mechanistic arguments about which organisms can be potentially airborne and therefore aerosol-transmissible, ultimately, the main deciding factor appears to be how many studies using various differing approaches: empirical (clinical, epidemiological), and/or experimental (e.g. using animal models), and/or mechanistic (using airflow tracers and air-sampling) methods, reach the same consensus opinion. Over time, the scientific community will eventually form an impression of the predominant transmission route for that specific agent, even if the conclusion is one of mixed transmission routes, with different routes predominating depending on the specific situations. This is the case for influenza viruses, and is likely the most realistic. Some bacterial and viral infections that have more than one mode of transmission are also anisotropic, like anthrax, plague, tularemia and smallpox: the ***severity of the disease varies depending on the mode of transmission** [37, 89]. Older experimental infection experiments on volunteers suggest that this is the case for influenza, with transmission by aerosols being associated with a more severe illness [14, 90], and some more recent field observations are consistent with this concept [57]. For anisotropic agents, even if a mode of transmission (e.g. aerosols) accounts for only a minority of cases, interruption of that route of transmission may be required if it accounts for the most severe cases."

Abstract. Annual influenza epidemics in the United States result in an average of >36,000 deaths and 114,000 hospitalizations. Influenza can spread rapidly

"The successful transmission of infection via the airborne route relies on several factors, including the survival of the airborne pathogen in the environment as it travels between susceptible hosts. This review summarizes the various environmental factors (particularly temperature and relative humidity) that may affect the airborne survival of viruses, bacteria and fungi, with the aim of highlighting specific aspects of environmental control that may eventually enhance the aerosol or airborne infection control of infectious disease transmission within hospitals."

1999

Validation of an EDP assisted model for assessing inhalation exposure and dermal exposure during spraying processes

This chapter deals with airborne particle contamination in food processing indoor environments and particularly within heating, ventilation, and

{Discussion of many control measures.} Several tiny organisms of various size ranges present in air are called airborne particles or bioaerosol which mainly includes live or dead fungi and bacteria, their secondary metabolites, viruses, pollens, etc. which have been related to health issues ...

"The microbial load was not affected significantly by the temperature, relative humidity, working shift, season, and number of visitors, indicating the effectiveness of a well-designed ventilation system to eliminate site-specific variations. ..A significant correlation was only observed between the number of particles with a diameter of > 10 μm and the airborne microbial loading. Thus, passive sampling may not properly reflect the actual concentrations of smaller bioaerosols. In conclusion, HEPA filters in the HVAC system successfully decreased the bioaerosol concentrations in the hospital environment."

Ventilation with outdoor air plays an important role influencing human exposures to indoor pollutants. This review and assessment indicates that increasing ventilation rates above currently adopted standards and guidelines should result in reduced prevalence of negative health outcomes. Building ope …

A new expiratory droplet investigation system (EDIS) was used to conduct the most comprehensive program of study to date, of the dilution corrected dr…

Recent studies have investigated the efficacy of air-cleaning products against pathogens in the air. A standard method to evaluate the reduction in airborne viruses caused by an air cleaner has been established using a safe bacteriophage instead of pathogenic viruses; the reduction in airborne viru …

Certain respiratory tract infections are transmitted through air. Coughing and sneezing by an infected person can emit pathogen-containing particles with diameters less than 10 μm that can reach the alveolar region. Based on our analysis of the ...

The coronavirus disease‐2019 (COVID‐19) pandemic has heightened the awareness of aerosol generation by human expiratory events and their potential role in viral respiratory disease transmission. Concerns over high severe acute respiratory ...

{Viruses-- probly applies to SARS-COV-2} Many airborne viruses have been shown to be sensitive to ambient humidity, yet the mechanisms responsible for this phenomenon remain elusive. We review multiple hypotheses, including water activity, surface inactivation, and salt toxicity, that may account for the association between humidity and viability of viruses in aerosols. We assess the evidence and limitations for each hypothesis based on findings from virology, aerosol science, chemistry, and physics. In addition, we hypothesize that changes in pH within the aerosol that are induced by evaporation may trigger conformational changes of the surface glycoproteins of enveloped viruses and subsequently compromise their infectivity. This hypothesis may explain the differing responses of enveloped viruses to humidity. The precise mechanisms underlying the relationship remain largely unverified, and attaining a complete understanding of them will require an interdisciplinary approach.

Air pollution has happened to be one of the mounting alarms to be concerned with in many Indian cities. COVID-19 epidemic endow with a unique opportunity to report the degree of air quality improvement due to the nationwide lockdown in 10 most polluted cities across the country. National Air Quality …

{High # of particulates in outdoor air may correlate with higher COVID-19 occurrence} A number of nations were forced to declare a total shutdown due to COVID-19 infection, as extreme measure to cope with dramatic impact of the pandemic, with remarkable consequences both in terms of negative health outcomes and economic loses. However, in many countries a "Phase-2" is approaching and …

(2019). "deeper understanding and more efficient utilization of bioaerosol studies to prevent public health hazards" "Mycotoxins, defined as secondary metabolites of fungi, are harmful indoor-air contaminants associated with mold growth in buildings and are known to cause several diseases such as cancer, hepatitis, and nephritis (Jarvis and Miller 2005). A component in the cell wall of fungi, (1→3)-β-d-glucan, is believed to play a role in pulmonary inflammation, increased sensitivity to endotoxins, and pulmonary embolisms."

This letter responds to your question concerning the possibility that SARS-CoV-2 could be spread by conversation, in addition to sneeze/cough-induced droplets.

This JAMA Insights Clinical Update discusses the need to better understand the dynamics of respiratory disease transmission by better characterizing transmission routes, the role of patient physiology in shaping them, and best approaches for source control in the context of the COVID-19 outbreak.

Humidity has strong impact on influenza survival on stainless steel surfaces. Etc. Contagion on airplanes, esp airborne.

The pandemic outbreak of the novel coronavirus epidemic disease (COVID-19) is spreading like a diffusion-reaction in the world and almost 208 countries and territories are being affected around the globe. It became a sever health and socio-economic problem, ...

It has been confirmed that the coronavirus disease 2019 (COVID-19) can transmit through droplets created when an infected human coughs or sneezes. Accordingly, 1.83-m (6-feet) social distancing is advised to reduce the spread of the disease among humans. This is based on the assumption that no air c …

“If it could easily exist as an aerosol, we would be seeing much greater levels of transmission" of the new coronavirus, said one epidemiologist.