Search

The importance of mitigating air pollution is well understood, while the role of trade on health burden induced by air pollution is not. A comparison between the geographic locations of PM emissions and those of airborne diseases shows large discrepancy. The incidence of PM emissions is dominated by countries outside of Asia, while half of the airborne disease burden occurs in China and India. Dealing with the air pollution issue from the endpoint (i.e. PM emissions-caused disease) is more relevant to health. Though there are many influential factors that cause high health burden of air pollution in developing countries, the high airborne disease burden caused by production in developing countries for fulfilling the demand for goods in developed countries cannot be ignored. We calculate the airborne disease footprints of 189 countries, and link the workers who are suffering from severe airborne disease with the consumers who are enjoying the goods without suffering the health risks of workers. China and India are the top two net exporters of both PM emissions and PM-caused airborne disease, but the net exports are much larger in terms of disease. The USA is the top net importer of airborne disease, followed by other developed nations such as Japan, Hong Kong, the UAE, and many wealthy European nations. These results can be helpful for international organizations and policy-makers to guide joint global efforts for combatting airborne diseases.

Local and state governments find it challenging to adopt aggressive residential building codes that require energy-efficiency upgrades beyond those with a reasonable payback. Thus, economic considerations inhibit the progress towards a more energy-efficient housing stock and often account for direct utility savings. A widely discussed solution is to look beyond energy costs and consider other impacts of energy-saving strategies that affect their financial attractiveness. In this paper, we examine the case of a public housing project in Phoenix, AZ, using several tools to calculate different economic, environmental, and health metrics associated with the three levels of energy efficiency. Our results show that while the payback calculated from direct energy costs may not be attractive, we should consider other savings. We demonstrate that avoided health and climate costs could total around 40% of the direct utility savings. In addition, we quantify how energy-saving strategies can cool the neighborhood, make buildings more resilient to heat, improve indoor air quality, and reduce the transmission of airborne disease. These benefits could be translated to avoid costs in the future.

Summary Objectives For tuberculosis (TB) transmission to occur, an uninfected individual must inhale the previously infected breath. Our objective was to identify potential TB transmission hotspots in metropolitan city of Dar es Salaam, Tanzania and to model the annual risk of TB transmission in different locations of public importance. Methods We collected indoor carbon dioxide (CO 2 ) data from markets, prisons, night clubs, public transportation, religious and social halls, and from schools. Study volunteers recorded social contacts at each of the locations. We then estimated the annual risks of TB transmission using a modified Wells-Riley equation for different locations. Results The annual risks of TB transmission were highest among prison inmates (41.6%) and drivers (20.3%) in public transport. Lower transmission risks were found in central markets (4.8% for traders, but 0.5% for their customers), passengers on public transport (2.4%), public schools (4.0%), nightclubs (1.7%), religious (0.13%), and social halls (0.12%). Conclusion For the first time in a country representative of sub-Saharan Africa, we modelled the risk of TB transmission in important public locations by using a novel approach of studying airborne transmission. This approach can guide identification of TB transmission hotspots and targeted interventions to reach WHO's ambitious End TB targets.

To date, few studies have examined the aerosol microbial content in Metro transportation systems. Here we characterised the aerosol microbial abundance, diversity and composition in the Athens underground railway system. PM10 filter samples were collected from the naturally ventilated Athens Metro Line 3 station “Nomismatokopio”. Quantitative PCR of the 16S rRNA gene and high throughput amplicon sequencing of the 16S rRNA gene and internal transcribed spacer (ITS) region was performed on DNA extracted from PM10 samples. Results showed that, despite the bacterial abundance (mean = 2.82 × 105 16S rRNA genes/m3 of air) being, on average, higher during day-time and weekdays, compared to night-time and weekends, respectively, the differences were not statistically significant. The average PM10 mass concentration on the platform was 107 μg/m3. However, there was no significant correlation between 16S rRNA gene abundance and overall PM10 levels. The Athens Metro air microbiome was mostly dominated by bacterial and fungal taxa of environmental origin (e.g. Paracoccus, Sphingomonas, Cladosporium, Mycosphaerella, Antrodia) with a lower contribution of human commensal bacteria (e.g. Corynebacterium, Staphylococcus). This study highlights the importance of both outdoor air and commuters as sources in shaping aerosol microbial communities. To our knowledge, this is the first study to characterise the mycobiome diversity in the air of a Metro environment based on amplicon sequencing of the ITS region. In conclusion, this study presents the first microbial characterisation of PM10 in the Athens Metro, contributing to the growing body of microbiome exploration within urban transit networks. Moreover, this study shows the vulnerability of public transport to airborne disease transmission.

Using aerobiology and engineering strategies to study particle movement in ventilated rooms is a powerful tool for understanding airborne disease transmission in healthcare facilities. More research is needed on movement of particles in ventilated rooms and more empirical data is needed to show effects of air exchange rates on particulate movement within a simple ventilated space. Results from this study can provide data for more complex strategies like Computational Fluid Dynamics (CFD) to help design ventilation systems in healthcare facilities where airborne disease transmission is a concern. In this study, particles were injected into a reduced-scale chamber to measure particle mass concentrations at twelve locations throughout the ventilated space and at the ventilation exhaust. Experiments had three particle sizes (1.9, 5.4, and 7.9 μm) of borosilicate glass, five levels of ventilation rate (nominally 2, 4, 6, 8 and 12 air changes per hour), and two injection locations (center and side). The ventilation system had one round inlet centered in one wall at ¾ height and one outlet in the opposite wall. Three replications were conducted for each combination of variables for a total of 90 tests. Increasing ventilation rates reduced concentrations of 1.9 μm particles in the occupied zone but had little effect on room concentrations of 5.4 and 7.9 μm particles. Exit concentrations for 1.9 μm particles were higher than for 5.4 and 7.9 μm particles. For 1.9 μm particles, average concentrations decreased linearly with increasing ventilation, while similar trends were not seen for the larger particles.

SummaryTuberculosis (TB) is an airborne disease caused by Mycobacterium tuberculosis (MTB) that usually affects the lungs leading to severe coughing, fever, and chest pains. Although current research in the past four years has provided valuable insight into TB transmission, diagnosis, and treatment, much remains to be discovered to effectively decrease the incidence of and eventually eradicate TB. The disease still puts a strain on public health, being only second to HIV/AIDS in causing high mortality rates. This review will highlight the history of TB as well as provide an overview of the current literature on epidemiology, pathogenesis and the immune response, treatment, and control of TB. In this race to combat a disease that knows no boundaries, it is necessary to have a conceptual and clear understanding of TB overall with the hope of providing better treatment through novel and collaborative research and public health efforts.

Influenza A H1N1/2009 is a highly infectious, rapidly spreading airborne disease that needs to be monitored in near real time, preferably in a microfluidic format. However, such demonstration is difficult to find as H1N1 concentration in aerosol samples is extremely low, with interference from dust particles. In this work, we measured Mie scatter intensities from a microfluidic device with optical waveguide channels, where the antibody-conjugated latex beads immunoagglutinated with the target H1N1 antigens. Through careful optimizations of optical parameters, we were able to maximize the Mie scatter increase from the latex immunoagglutinations while minimizing the background scatter from the dust particles. The aerosol samples were collected from a 1:10 mock classroom using a button air sampler, where a nebulizer generated aerosols, simulating human coughing. The detection limits with real aerosol samples were 1 and 10 pg/mL, using a spectrometer or a cell phone camera as an optical detector, respectively. These are several orders of magnitudes more sensitive than the other methods. The microfluidic immunosensor readings are in concordance with the results of reverse transcription polymerase chain reaction. The assay time was 30 s for sampling and 5 min for the microfluidic assay.

Precise prediction of particulate movement is needed to provide a better understanding of how airborne disease organisms move within ventilated facilities. Bacteria often adhere to larger airborne particulates, which will modify their movement behavior in ventilated rooms and may provide an environment to allow them to remain virulent longer. An empty chamber (206 H × 203 W × 386 cm L) with a circular air inlet and outlet on opposite ends was ventilated with air that had a known particulate density. The inlet and outlet openings were sized to maintain inlet and exit velocities at around 5.1 m/s at 5 different air exchange rates (around 2, 4, 5, 9, and 14 air changes per hour – ACH). Particulate concentrations were measured at the air outlet and at 12 locations within the chamber. In this study, the particulate concentration in the inlet air remained constant, so the amount of particulates injected into the chamber increased as the ACH increased. The measured particulate levels at the outlet also increased essentially linearly with an increase in ACH. However, the particulate concentrations in the occupied zone of the chamber did not increase linearly with an increase in actual ACH. Rather, it increased essentially linearly at the lower ACH levels (from around 2 to 5 ACH), but then leveled out at the higher ACH values. The advantages of increasing ACH in terms of providing better environments in the occupied zone of rooms may have limits, which warrant further investigation.

Resent respiratory infection outbreak events, including Avian and Swine Influenza and SARS virus spread in various countries ignited a strong interest towards investigations in the area of airborne virus behavior in the ambient air. One of the most important parameters, related to airborne disease transmission is survival of disease causing microorganisms in the ambient air environment. This project investigates survival of airborne influenza virus of different sub-types at common room conditions where risk of disease due to microbial transmission could be particularly high, especially at poorly ventilated environments, where viral concentration in the air reaches significant magnitudes. The results obtained for H1N1 and H5N1 strains show close trend with regards to inactivation in the ambient air; rapid inactivation of approximately 60% of microorganisms over the first 30 min with following inactivation at much slower rate over the remaining 60 min of experiment. A different picture was observed for the H3N2 strain, which demonstrated much higher robustness compared to other subtypes; even after 90 min, around 50% of viral particles were still alive. The results of this research could be directly utilized in health and epidemiological studies, modeling of HVAC systems, microbiological studies and many others.

SummaryMeasles among healthcare workers (HCWs) is associated with a significant risk of nosocomial transmission to susceptible patients. When a measles case occurs in the healthcare setting, most guidelines recommend exhaustive measures. To evaluate the effects of measures against measles transmission in the healthcare setting precisely, it is essential to determine whether secondary transmission generally occurs. This study describes, for the first time, the actual secondary transmission rate for a measles-infected HCW in a ward with no special air ventilation capacity. The routine treatment of a number of immunocompromised patients occurs in this ward, and thus patients as well as HCWs have a thorough understanding and practice of standard and extended precautions. Our paired serum sample study revealed that none of the people in the ward exposed to the HCW at the catarrhal stage over a period of 4 days exhibited elevated levels of antibodies against measles. We suggest that strict adherence to standard and expanded precautions among patients and HCWs may be effective for preventing the transmission of a highly airborne disease, such as measles.

Good ventilation is an important part of any livestock housing system. It may be accomplished by either natural or mechanical means. Generally, except for buildings that must be kept at warm, nonfluctuating temperatures, naturally ventilated cold housing is satisfactory for sheep and goats provided it is dry and draft-free in pen and resting areas, and air exchange is taking place at a rate high enough to remove moisture, gases, and airborne disease organisms from the building. Understanding the importance of site location, building orientation, and principles of ventilation design increases the likelihood of successful barn ventilation.