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      Uma análise comparativa do desempenho de quatro sistemas de umidificação do ar em condições de seca no centro-oeste brasileiro Translated title: A comparative performance analysis of four air humidification systems under drought conditions in the Brazilian Midwest

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          Abstract

          Resumo Quatro sistemas de umidificação do ar foram examinados e seus desempenhos comparados sob condições de seca do centro-oeste brasileiro. Esses sistemas são umidificador elétrico, bacia com água, toalha úmida e um sistema artesanal feito com telhas cerâmicas especialmente para este trabalho. A avaliação foi realizada entre julho e outubro de 2017, em Cuiabá, Brasil. As medidas da umidade relativa foram feitas em dois ambientes semelhantes, um com e outro sem sistema de umidificação. O umidificador elétrico proporcionou umidificação contínua e prolongada, mantendo essa condição até o final dos períodos de medições, mas destacam-se os altos tempos de resposta para umidificar um espaço, de até 292 min, e umidade relativa alcançada, de 85%, após tempos de operação mais longos. O sistema da bacia com água resultou numa umidificação de aproximadamente 59% da alcançada pelo umidificador elétrico, enquanto a toalha úmida, apesar do menor tempo de resposta em umidificar o ambiente, de até 18 min, não manteve a umidade de referência até o final dos períodos de medições, sob condição de 43% de umidade relativa, em média. O sistema artesanal proporcionou uma umidificação de cerca de 92% da umidade fornecida pelo umidificador elétrico, o que demonstra o potencial benefício do sistema em umidificar ambientes fechados.

          Translated abstract

          Abstract This study examined four air humidification systems and compared their performances under drought conditions in the Brazilian Midwest. Those systems were the electric humidifier, basin with water, wet towel, and an artisanal system made for this study using clay roof tiles. The evaluation was conducted between July and October 2017 in Cuiabá, Brazil. The measurements of the relative humidity were taken in two similar bedrooms, one without a humidifier and another one with an air humidification system. The electric air humidifier provided a continuous and prolonged humidification, maintaining this condition until the end of the measurement period in all situations, but the study highlights the high response time to humidify a space, up to 292 min, and the high relative humidity, around 85%, provided by the humidifier after longer running times. The basin with water system resulted in a humidification of about 59% of the moisture provided by the electric humidifier, while the wet towel, despite producing the best response time in humidifying an environment - up to 18 min, did not maintain the reference humidity until the end of the measurement period under ambient conditions of 43% relative humidity. The artisanal system presented a humidification of about 92% of the moisture provided by the electric humidifier, which demonstrates the potential of the system to increase humidity indoors.

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          Indirect health effects of relative humidity in indoor environments.

          A review of the health effects of relative humidity in indoor environments suggests that relative humidity can affect the incidence of respiratory infections and allergies. Experimental studies on airborne-transmitted infectious bacteria and viruses have shown that the survival or infectivity of these organisms is minimized by exposure to relative humidities between 40 and 70%. Nine epidemiological studies examined the relationship between the number of respiratory infections or absenteeism and the relative humidity of the office, residence, or school. The incidence of absenteeism or respiratory infections was found to be lower among people working or living in environments with mid-range versus low or high relative humidities. The indoor size of allergenic mite and fungal populations is directly dependent upon the relative humidity. Mite populations are minimized when the relative humidity is below 50% and reach a maximum size at 80% relative humidity. Most species of fungi cannot grow unless the relative humidity exceeds 60%. Relative humidity also affects the rate of offgassing of formaldehyde from indoor building materials, the rate of formation of acids and salts from sulfur and nitrogen dioxide, and the rate of formation of ozone. The influence of relative humidity on the abundance of allergens, pathogens, and noxious chemicals suggests that indoor relative humidity levels should be considered as a factor of indoor air quality. The majority of adverse health effects caused by relative humidity would be minimized by maintaining indoor levels between 40 and 60%. This would require humidification during winter in areas with cold winter climates. Humidification should preferably use evaporative or steam humidifiers, as cool mist humidifiers can disseminate aerosols contaminated with allergens.
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            Modeling the airborne survival of influenza virus in a residential setting: the impacts of home humidification

            Background Laboratory research studies indicate that aerosolized influenza viruses survive for longer periods at low relative humidity (RH) conditions. Further analysis has shown that absolute humidity (AH) may be an improved predictor of virus survival in the environment. Maintaining airborne moisture levels that reduce survival of the virus in the air and on surfaces could be another tool for managing public health risks of influenza. Methods A multi-zone indoor air quality model was used to evaluate the ability of portable humidifiers to control moisture content of the air and the potential related benefit of decreasing survival of influenza viruses in single-family residences. We modeled indoor AH and influenza virus concentrations during winter months (Northeast US) using the CONTAM multi-zone indoor air quality model. A two-story residential template was used under two different ventilation conditions - forced hot air and radiant heating. Humidity was evaluated on a room-specific and whole house basis. Estimates of emission rates for influenza virus were particle-size specific and derived from published studies and included emissions during both tidal breathing and coughing events. The survival of the influenza virus was determined based on the established relationship between AH and virus survival. Results The presence of a portable humidifier with an output of 0.16 kg water per hour in the bedroom resulted in an increase in median sleeping hours AH/RH levels of 11 to 19% compared to periods without a humidifier present. The associated percent decrease in influenza virus survival was 17.5 - 31.6%. Distribution of water vapor through a residence was estimated to yield 3 to 12% increases in AH/RH and 7.8-13.9% reductions in influenza virus survival. Conclusion This modeling analysis demonstrates the potential benefit of portable residential humidifiers in reducing the survival of aerosolized influenza virus by controlling humidity indoors.
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              Experimental study of cooling effects of a passive evaporative cooling wall constructed of porous ceramics with high water soaking-up ability

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                Author and article information

                Contributors
                Role: ND
                Journal
                ac
                Ambiente Construído
                Ambient. constr.
                Associação Nacional de Tecnologia do Ambiente Construído - ANTAC (Porto Alegre, RS, Brazil )
                1678-8621
                April 2019
                : 19
                : 2
                : 187-202
                Affiliations
                [1] Cuiabá Mato Grosso orgnameUniversidade Federal de Mato Grosso Brazil
                Article
                S1678-86212019000200187
                10.1590/s1678-86212019000200316
                f9179bd3-4c63-4182-9609-56799cafcc80

                This work is licensed under a Creative Commons Attribution 4.0 International License.

                History
                : 04 May 2018
                : 26 July 2018
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 29, Pages: 16
                Product

                SciELO Brazil

                Categories
                Artigos

                Conforto ambiental,Umidade do Ar no Interior das edificações,Umidificadores,Air quality,Environmental comfort,Indoor residential humidity,Humidifiers,Qualidade do ar

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