There have been few recent studies demonstrating a definitive association between the transmission of airborne infections and the ventilation of buildings. The severe acute respiratory syndrome (SARS) epidemic in 2003 and current concerns about the risk of an avian influenza (H5N1) pandemic, have made a review of this area timely. We searched the major literature databases between 1960 and 2005, and then screened titles and abstracts, and finally selected 40 original studies based on a set of criteria. We established a review panel comprising medical and engineering experts in the fields of microbiology, medicine, epidemiology, indoor air quality, building ventilation, etc. Most panel members had experience with research into the 2003 SARS epidemic. The panel systematically assessed 40 original studies through both individual assessment and a 2-day face-to-face consensus meeting. Ten of 40 studies reviewed were considered to be conclusive with regard to the association between building ventilation and the transmission of airborne infection. There is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS. There is insufficient data to specify and quantify the minimum ventilation requirements in hospitals, schools, offices, homes and isolation rooms in relation to spread of infectious diseases via the airborne route. PRACTICAL IMPLICATION: The strong and sufficient evidence of the association between ventilation, the control of airflow direction in buildings, and the transmission and spread of infectious diseases supports the use of negatively pressurized isolation rooms for patients with these diseases in hospitals, in addition to the use of other engineering control methods. However, the lack of sufficient data on the specification and quantification of the minimum ventilation requirements in hospitals, schools and offices in relation to the spread of airborne infectious diseases, suggest the existence of a knowledge gap. Our study reveals a strong need for a multidisciplinary study in investigating disease outbreaks, and the impact of indoor air environments on the spread of airborne infectious diseases.

Role of ventilation in airborne transmission of infectious agents in the built environment - a multidisciplinary systematic review.

There have been few recent studies demonstrating a definitive associ- ation between the transmission of airborne infections and the ventilation of buildings. The severe acute respiratory syndrome (SARS) epidemic in 2003 and current concerns about the risk of an avian influenza (H5N1) pandemic, have made a review of this area timely. We searched the major literature databases between 1960 and 2005, and then screened titles and abstracts, and finally selected 40 original studies based on a set of criteria. We established a review panel comprising medical and engineering experts in the fields of microbiology, medicine, epidemiology, indoor air quality, building ventilation, etc. Most panel members had experience with research into the 2003 SARS epidemic. The panel systematically assessed 40 original studies through both individual assessment and a 2-day face-to-face consensus meeting. Ten of 40 studies reviewed were considered to be conclusive with regard to the association between building ventilation and the transmission of airborne infection. There is strong and suf- ficient evidence to demonstrate the association between ventilation, air move- ments in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS. There is insufficient data to specify and quantify the minimum ventilation requirements in hospitals, schools, offices, homes and isolation rooms in relation to spread of infectious diseases via the airborne route.

Review Article Role of ventilation in airborne transmission of infectious agents in the built environment - a multidisciplinary systematic review

Background Allergenic diseases triggered by aeroallergens extract a health cost in quality of life and in economic impact. People generally spend 90% to 95% of their time indoors, so understanding the environmental factors that affect the presence of aeroallergens indoors are important in understanding health impact and potential intervention methods. Objective To describe the relationship of indoor airborne pollen and fungal spores in occupied mobile homes with outdoor concentrations and other environmental factors within geographically diverse areas of Texas. Methods Airborne pollen and fungal spores were collected during the daytime with RotoRod samplers indoor and outdoor of mobile homes in Houston and El Paso, Texas. Samples were counted simultaneously with a dual eyepiece microscope and identified morphologically and through staining techniques. Results Geometric mean concentrations (counts/m 3 ) indoors and outdoors for pollen, respectively, were Houston 7.1 and 196.4; and El Paso 17.5 and 71.5. Gometric mean concentrations (counts/m 3 ) indoors and outdoors for spore, respectively, were Houston 98.5 and 196.4; and El Paso 36.9 and 71.5. Indoor to outdoor ratios (I/O) for pollen and fungal spores were found to be higher on average than has been previously reported. Modeling of predictive factors in Houston demonstrate that 62% and 41% of indoor levels of pollen and fungal spores, respectively, can be explained by their corresponding outdoor levels. These data suggest that the many factors associated with individual exposure to airborne pollen and fungal spores indoors are under the control of the occupant, and may additionally be influenced by the physical characteristics of mobile homes, in particular the high surface area to volume ratio and restricted flow patterns.

Pollen and fungal spores indoor and outdoor of mobile homes

Characterizing moisture damaged buildings : Environmental and biological monitoring

Background : According to observations by occupational health physicians, nearly
50 % of the seamen on German vessels will get diseases of the upper respiratory tract.
An impact of the air-conditioning systems on these diseases has been suggested.
 Objectives : To examine the hygienic quality of indoor air on seagoing vessels, a
pilot study was initiated by the See-Berufsgenossenschaft.
 Methods : Air samples were taken on-site at different sampling sites and analysed
for the occurrence of microorganisms.
Results: Bacteria showed the highest cell numbers and the highest distribution in
indoor air on vessels, whereby the maximum level was determined in the air of crew
cabins. The identification of bacteria showed that beside common airborne species,
pathogens existed.
 Conclusions : Air-conditioning seems to influence the quality of indoor air on
seagoing vessels. Interim results of the study indicate that regular maintenance of airconditioning
systems is essential.

https://www.imh.mug.edu.pl/attachment/attachment/4982/2007_x06.pdf

Does air conditioning impact on hygienic quality of indoor air on seagoing vessels

In air-conditioned buildings indoor air quality is closely dependent on the efficiency of air-conditioning and humidifier systems since these systems provide a suitable environment for the proliferation of microorganisms. Pollutants released by microorganisms are termed 'bioaerosols' and may be spread in the indoor environment through the air-conditioning system. Moreover, the tightening of the buildings in which central air-conditioning systems are usually located increases the levels of indoor pollutants. Both hypersensitivity and infectious diseases are associated with bioaerosol exposure, whereas the sick building syndrome (a complex of symptoms described among workers in modern office buildings which are hermetically sealed and mechanically ventilated) is very unlikely to have a bioaerosol component.

G L Rossi

Papers

Human health and air conditioning systems.