Klas Nordström

Effect of Air Humidification on the Sick Building Syndrome and Perceived Indoor Air Quality in Hospitals: a Four Month Longitudinal Study

The sensation of dryness and irritation is essential in the sick building syndrome (SBS), and such symptoms are common in both office and hospital employees. In Scandinavia, the indoor relative humidity in well ventilated buildings is usually in the range 10-35% in winter. The aim of this study was to evaluate the effect of steam air humidification on SBS and perceived air quality during the heating season. The study base consisted of a dynamic population of 104 hospital employees, working in four new and well ventilated geriatric hospital units in southern Sweden. Air humidification raised the relative air humidity to 40-45% in two units during a four months period, whereas the other two units served as controls with relative humidity from 25-35%. Symptoms and perceived indoor air quality were measured before and after the study period by a standardised self administered questionnaire. The technical measurements comprised room temperature, air humidity, static electricity, exhaust air flow, aerosols, microorganisms, and volatile organic compounds in the air. The most pronounced effect of the humidification was a significant decrease of the sensation of air dryness, static electricity, and airway symptoms. After four months of air humidification during the heating season, 24% reported a weekly sensation of dryness in humidified units, compared with 73% in controls. No significant changes in symptoms of SBS or perceived air quality over time were found in the control group. The room temperature in all units was between 21-23 degrees C, and no significant effect of air humidification on the air concentration of aerosols or volatile organic compounds was found. No growth of microorganisms was found in the supply air ducts, and no legionella bacteria were found in the supply water of the humidifier. Air humidification, however, significantly reduced the measured personal exposure to static electricity. It is concluded that air humidification during the heating season in colder climates can decrease symptoms of SBS and perception of dry air.

Influence of Indoor Air Quality and Personal Factors on the Sick Building Syndrome (SBS) in Swedish Geriatric Hospitals

OBJECTIVES--Sick building syndrome (SBS) involves symptoms such as irritation to the eyes, skin, and upper airways, headache, and fatigue. The relations between such symptoms and both personal and environmental factors were studied in 225 female hospital workers, working in eight hospital units in the south of Sweden. METHODS--Symptoms of SBS and personal factors were measured by means of a standardised self administered questionnaire. The technical investigation comprised a building survey and measurements of room temperature, supply air temperature, air humidity, and exhaust air flow. RESULTS--The prevalence of symptoms differed from one unit to another. The mean value of weekly complaints of fatigue was 30%, of eye irritation 23%, and of dry facial skin 34%. Eye irritation was related to work stress, self reported exposure to static electricity, and was also more common in buildings with a high ventilation flow and a high noise level (55 dB(A)) from the ventilation system. Nasal symptoms were related to asthma and hay fever only. Throat symptoms were more common in smokers, subjects with asthma or hay fever, new buildings, and in buildings with a high ventilation flow. Facial skin irritation was related to a lack of control of the work conditions, and was more common in new buildings, and buildings with a high ventilation flow and ventilation noise. General symptoms, such as headache and fatigue, were related to current smoking, asthma or hay fever, work dissatisfaction, and static electricity. CONCLUSION--As the prevalence of symptoms was high, there is a need to improve the indoor environment as well as the psychosocial environment in hospitals. These improvements could include a reduction of ventilation noise, minimised smoking, and improvements in the psychosocial climate. Further research is needed to identify indoor climatic factors that cause the increased prevalence of symptoms of SBS in new buildings.

An experimental study on effects of increased ventilation flow on students’ perception of indoor environment in computer classrooms

UNLABELLED The effects of ventilation in computer classrooms were studied with university students (n = 355) in a blinded study, 31% were women and 3.8% had asthma. Two classrooms had a higher air exchange (4.1-5.2 ac/h); two others had a lower air exchange (2.3-2.6 ac/h). After 1 week, ventilation conditions were shifted. The students reported environmental perceptions during the last hour. Room temperature, RH, CO2, PM10 and ultra-fine particles were measured simultaneously. Mean CO2 was 1185 ppm at lower and 922 ppm at higher air exchange. Mean temperature was 23.2 degrees C at lower and 22.1 degrees C at higher air exchange. After mutual adjustment (temperature, RH, CO2, air exchange), measured temperature was associated with a perception of higher temperature (P < 0.001), lower air movement (P < 0.001), and poorer air quality (P < 0.001). Higher air exchange was associated with a perception of lower temperature (P < 0.001), higher air movement (P = 0.001), and better air quality (P < 0.001). In the longitudinal analysis (n = 83), increased air exchange caused a perception of lower temperature (P = 0.002), higher air movement (P < 0.001), better air quality (P = 0.001), and less odor (P = 0.02). In conclusion, computer classrooms have CO2 levels above 1000 ppm and temperatures above 22 degrees C. Increased ventilation from 7 l/s per person to 10-13 l/s per person can improve thermal comfort and air quality. PRACTICAL IMPLICATIONS Computer classrooms are crowded indoor environments with a high thermal load from both students and computer equipment. It is important to control room temperature either by air conditioning, sun shields, or sufficiently high ventilation flow. A high ventilation flow is also crucial to achieving good perceived air quality. Personal ventilation flow should be at least 10 l/s. Possible loss of learning ability due to poor indoor air quality in university buildings deserves more attention.

Subjective Indoor Air Quality in Hospitals - The Influence of Building Age, Ventilation Flow, and Personal Factors

Relationships between subjective perception of indoor air quality, building characteristics, indoor exposures, and personal factors were studied in 225 female Swedish hospital workers. The prevalence of weekly complaints to do with dry air was 87% for air dryness, and 36% for static electricity. Such com plaints were more common in new and well ventilated buildings. The sensa tion of air dryness was also more common in buildings with damp concrete slabs. In contrast, complaints about odours and stuffy air were most prevalent in old buildings with a poor outdoor air supply, and not related to building dampness. Complaints about odour were, however, more common in build ings with higher relative air humidity. Complaints of noise were related to measured noise (55 dB(A)) from the ventilation system. The high complaint rate, particularly of dry air, shows a need to improve the indoor environment in hospitals.

The effect of building dampness and type of building on eye, nose and throat symptoms in Swedish hospitals

The effect of building dampness and type of building on eye, nose and throat symptoms in Swedish hospitals