من انا

صورتي
الرياض, Saudi Arabia
مسلم، وأناأحوج ما أكون إلى معرفة نفسي

الثلاثاء، 31 يناير، 2012

Influence of micro-organisms on the air


Influence of micro-organisms on the air
Most of our life is spent indoors. Therefore, indoor air pollution may present a greater risk to human health than exposure to atmospheric air contaminants. One kind of indoor air pollutant is airborne microorganisms – bacteria and fungi. They are factors of potential infectious, allergenic and immunotoxic effects. Indoor microflora is reported to be responsible for health problems, especially among children. Bioaerosols decrease air quality and affect human health, also causing some diseases such as tuberculosis, diphteria, legionellosis, fever, rhinitis, nausea and asthma.
The activity of people and equipment within enclosed spaces is thought to be the principal factor contributing to the buildup and spread of airborne microbial contamination. Another major emission sources of indoor microbiological pollutants are animals, plants, air conditioning systems, building materials, particles of soil and dust. A lot of these come from outdoor air, especially in summer and autumn. School facilities are densely populated, so it’s making the problem of maintaining good quality indoor environments more difficult.
Poor indoor air quality causes in many cases illness requiring absence from school or can cause acute health symptoms, decreasing performance while at school. Children are more likely to suffer the consequences of indoor pollutants than adults, because they are still developing physically. It has been stated that especially the presence of moulds in indoor air of schools poses a serious risk to children. All moulds have the potential to cause health effects such as headaches, breathing difficulties, skin irritation, allergic reaction and aggravation of asthma symptoms. Epidemiological data suggest that mould exposure may increase the risk for asthma up to five-fold at school age.
Asthma is the principal cause of school absences (up to 20% of lost school days in elementary and high schools). Also, 14% of school children revealed a positive reaction to fungal allergens in skin prick tests and serum IgE reactions. An elevated occurrences of wheezing and fever in children was connected with high numbers of fungi in the air. To estimate a hazard of microbiological air pollution a number of fungi and various groups of bacteria indoors should be determined, as precisely as possible.
World Health Organization (WHO) guidelines for the protection of public health from health risks due to dampness, associated microbial growth and contamination of indoor spaces. The guidelines are based on a comprehensive review and evaluation of the accumulated scientific evidence by a multidisciplinary group of experts studying health effects of indoor air pollutants as well as those specialized in identification of the factors that contribute to microbial growth indoors.
Problems of indoor air quality are recognized as important risk factors for human health in both low-income and middle- and high-income countries. Indoor air is also important because populations spend a substantial fraction of time within buildings. In residences, day-care centers, retirement homes and other special environments, indoor air pollution affects population groups that are particularly vulnerable due to their health status or age. Microbial pollution involves hundreds of species of bacteria and fungi that grow indoors when sufficient moisture is available. Exposure to microbial contaminants is clinically associated with respiratory symptoms, allergies, asthma and immunological reactions.
The microbial indoor air pollutants of relevance to health are widely heterogeneous, ranging from pollen and spores of plants coming mainly from outdoors, to bacteria, fungi, algae and some protozoa emitted outdoors or indoors. They also include a wide variety of microbes and allergens that spread from person to person. There is strong evidence regarding the hazards posed by several biological agents that pollute indoor air; however, the WHO working group convened in October 2006 concluded that the individual species of microbes and other biological agents that are responsible for health effects cannot be identified. This is due to the fact that people are often exposed to multiple agents simultaneously, to complexities in accurately estimating exposure and to the large numbers of symptoms and health outcomes due to exposure.
The exceptions include some common allergies, which can be attributed to specific agents, such as house-dust mites and pets. The presence of many biological agents in the indoor environment is due to dampness and inadequate ventilation. Excess moisture on almost all indoor materials leads to growth of microbes, such as mould, fungi and bacteria, which subsequently emit spores, cells, fragments and volatile organic compounds into indoor air. Moreover, dampness initiates chemical or biological degradation of materials, which also pollutes indoor air. Dampness has therefore been suggested to be a strong, consistent indicator of risk of asthma and respiratory symptoms (e.g. cough and wheeze). The health risks of biological contaminants of indoor air could thus be addressed by considering dampness as the risk indicator.
The indoor environment in any building is a result of the interaction between the site, climate, building system (original design and later modifications in the structure and mechanical systems), construction techniques, contaminant sources (building materials and furnishings, moisture, processes and activities within the building and outdoor sources) and building occupants. Microbial sources may arise from pollen, dust or fungal spores. Stagnant water in the vicinity of buildings may also give rise to microbial sources which may ca
Most of our life is spent indoors. Therefore, indoor air pollution may present a greater risk to human health than exposure to atmospheric air contaminants. One kind of indoor air pollutant is airborne microorganisms – bacteria and fungi. They are factors of potential infectious, allergenic and immunotoxic effects. Indoor microflora is reported to be responsible for health problems, especially among children. Bioaerosols decrease air quality and affect human health, also causing some diseases such as tuberculosis, diphteria, legionellosis, fever, rhinitis, nausea and asthma.

The activity of people and equipment within enclosed spaces is thought to be the principal factor contributing to the buildup and spread of airborne microbial contamination. Another major emission sources of indoor microbiological pollutants are animals, plants, air conditioning systems, building materials, particles of soil and dust. A lot of these come from outdoor air, especially in summer and autumn. School facilities are densely populated, so it’s making the problem of maintaining good quality indoor environments more difficult.

Poor indoor air quality causes in many cases illness requiring absence from school or can cause acute health symptoms, decreasing performance while at school. Children are more likely to suffer the consequences of indoor pollutants than adults, because they are still developing physically. It has been stated that especially the presence of moulds in indoor air of schools poses a serious risk to children. All moulds have the potential to cause health effects such as headaches, breathing difficulties, skin irritation, allergic reaction and aggravation of asthma symptoms. Epidemiological data suggest that mould exposure may increase the risk for asthma up to five-fold at school age.

Asthma is the principal cause of school absences (up to 20% of lost school days in elementary and high schools). Also, 14% of school children revealed a positive reaction to fungal allergens in skin prick tests and serum IgE reactions. An elevated occurrences of wheezing and fever in children was connected with high numbers of fungi in the air. To estimate a hazard of microbiological air pollution a number of fungi and various groups of bacteria indoors should be determined, as precisely as possible.

World Health Organization (WHO) guidelines for the protection of public health from health risks due to dampness, associated microbial growth and contamination of indoor spaces. The guidelines are based on a comprehensive review and evaluation of the accumulated scientific evidence by a multidisciplinary group of experts studying health effects of indoor air pollutants as well as those specialized in identification of the factors that contribute to microbial growth indoors.

Problems of indoor air quality are recognized as important risk factors for human health in both low-income and middle- and high-income countries. Indoor air is also important because populations spend a substantial fraction of time within buildings. In residences, day-care centers, retirement homes and other special environments, indoor air pollution affects population groups that are particularly vulnerable due to their health status or age. Microbial pollution involves hundreds of species of bacteria and fungi that grow indoors when sufficient moisture is available. Exposure to microbial contaminants is clinically associated with respiratory symptoms, allergies, asthma and immunological reactions.

The microbial indoor air pollutants of relevance to health are widely heterogeneous, ranging from pollen and spores of plants coming mainly from outdoors, to bacteria, fungi, algae and some protozoa emitted outdoors or indoors. They also include a wide variety of microbes and allergens that spread from person to person. There is strong evidence regarding the hazards posed by several biological agents that pollute indoor air; however, the WHO working group convened in October 2006 concluded that the individual species of microbes and other biological agents that are responsible for health effects cannot be identified. This is due to the fact that people are often exposed to multiple agents simultaneously, to complexities in accurately estimating exposure and to the large numbers of symptoms and health outcomes due to exposure.

The exceptions include some common allergies, which can be attributed to specific agents, such as house-dust mites and pets. The presence of many biological agents in the indoor environment is due to dampness and inadequate ventilation. Excess moisture on almost all indoor materials leads to growth of microbes, such as mould, fungi and bacteria, which subsequently emit spores, cells, fragments and volatile organic compounds into indoor air. Moreover, dampness initiates chemical or biological degradation of materials, which also pollutes indoor air. Dampness has therefore been suggested to be a strong, consistent indicator of risk of asthma and respiratory symptoms (e.g. cough and wheeze). The health risks of biological contaminants of indoor air could thus be addressed by considering dampness as the risk indicator.
The indoor environment in any building is a result of the interaction between the site, climate, building system (original design and later modifications in the structure and mechanical systems), construction techniques, contaminant sources (building materials and furnishings, moisture, processes and activities within the building and outdoor sources) and building occupants. Microbial sources may arise from pollen, dust or fungal spores. Stagnant water in the vicinity of buildings may also give rise to microbial sources which may ca

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