The role of relative humidity and aerosol composition in airborne respiratory virus survival

This thesis presents and tests a novel hypothesis that attempts to predict the relative humidity (RH) dependent survival of airborne respiratory viruses in protein-enriched saline aerosols. The hypothesis proposed that virus-laden respiratory aerosols exist in either an effloresced (solid) or deliquesced (liquid) state, depending on the ambient air RH and that the survival of viruses embedded in such aerosols changes with that state. Experiments confirmed as predicted, that rhinovirus and influenza virus exhibited a V-shaped surviving fraction dependence on RH. Implications concerning the survival of these viruses under seasonal conditions are discussed along with strategies to control indoor airborne infection

Comments on: 'Meteorological correlates and AirQ+ health risk assessment of ambient fine particulate matter in Tehran, Iran'

The recently published article (https://doi.org/10.1016/j.envres.2018.11.046), authored by Mohsen Ansari and Mohammad Hassan Ehrampoush (2019), was read with keen interest and in detail. The article aimed to investigate the correlation between ambient fine particulate matter (PM2.5, particulate matter with aerodynamic diameter 2.5 μm and smaller) and meteorological parameters, such as temperature, humidity, precipitation and wind speed. Additionally, the World Health Organization AirQ + software, updated in 2016 by WHO European Centre for Environment and Health, was applied to estimate all-cause and also five specific causes of death (namely, ischemic heart disease (IHD), cerebrovascular disease (stroke), lung cancer (LC), chronic obstructive pulmonary disease (COPD) and acute lower respiratory infection (ALRI)) due to long-term exposure to PM2.5 in Tehran from for the year spanning March 2017 to March 2018. It was reported that the authors obtained hourly concentrations of ambient PM2.5 from Air Quality Monitoring Stations (AQMSs) operated by the Tehran Air Quality Control Company (TAQCC). Other required data also were gathered from governmental organizations, including the Statistical Centre of Iran (SCI), the Civil Registration Office of Tehran, and the Ministry of Health and Medical Education. We believe there are a number of controversial issues that should be brought to the attention of readers, especially within the materials and methods sections, including “Description of Study Area”, “Air Pollution Data Monitoring and Exposure Assessment” and “AirQ+ Software”; and in subsequent sections, we also highlight some issues impacting the interpretability of the article

Exposure to ambient air pollution and risk of childhood cancers: A population-based study in Tehran, Iran

The relationship between air pollution and childhood cancer is inconclusive. We investigated the associations between exposure to ambient air pollution and childhood cancers in Tehran, Iran. This project included children between 1 and 15 years-of-age with a cancer diagnosis by the Center for the Control of Non Communicable Disease (n = 161) during 2007 to 2009. Controls were selected randomly within the city using a Geographic Information System (GIS) (n = 761). The cases were geocoded based on exact home addresses. Air pollution exposure of cases and random controls were estimated by a previously developed Land Use Regression (LUR) model for the 2010 calendar year. The annual mean concentrations of Particulate Matter ≤ 10 μm (PM10), nitrogen dioxide (NO2) and sulfur dioxide (SO2) in the locations of cancer cases were 101.97 μg/m3, 49.42 ppb and 38.92 ppb respectively, while in the random control group, respective mean exposures were 98.63 μg/m3, 45.98 ppb and 38.95 ppb. A logistic regression model was used to find the probability of childhood cancer per unit increase in PM10, NO2 and SO2. We observed a positive association between exposures to PM10 with childhood cancers. We did, however, observe a positive, but not statistically significant association between NO2 exposure and childhood cancer. Our study is the first to highlight an association between air pollution exposure and childhood cancer risk in Iran, however these findings require replication through future studies

The state of the art characterisation of particles from respiratory activities

Over the past few decades, the options available for the study of particles emitted during human respiratory activities have expanded significantly. Here we provide a summary of this field of research and suggest future directions