Summary As a part of a worldwide investigation on the prevalence of respiratory symptoms, we have performed a study on the relationship between the indoor environment and asthma‐like symptoms in the population of a central Swedish municipality. The study comprised 88 individuals, aged 20–45 years who underwent a structured interview, spirometry, a methacholine provocation test, skin‐prick tests and blood samples for measurements of serum concentrations of eosinophil cationic protein (S‐ECP), blood eosinophil count and total immunoglobulin E (S‐IgE). In the homes, the room temperature, air humidity, respirable dust, house dust mites (HDM) and airborne micro‐organisms were measured. The relative humidity in all the homes was found to be above 33%. HDM were found in 13% of homes. In the homes of the 47 subjects with asthma related symptoms, significantly higher total levels of bacteria and mould ( P <0.05) and a higher proportion of detected HDM (OR = 5.3) was found than in subjects with no asthma related symptoms, after adjustment for age, sex, smoking, indoor temperature and air humidity. HDM were found to be an independent risk factor for asthma related symptoms (OR = 7.9) and nocturnal breathlessness (OR = 6.2) ( P <0.05), while the total level of bacteria was a risk factor for asthma related symptoms and wheezing ( P <0.05). We conclude that although HDM is relatively infrequently found in the homes of central‐Sweden, the presence of HDM is related to asthmatic symptoms. A relation between levels of airborne bacteria and asthma related symptoms was also found.

OBJECTIVES--As a part of the worldwide European Community respiratory health survey, possible relations between symptoms of asthma, building characteristics, and indoor concentration of volatile organic compounds (VOCs) in dwellings were studied. METHODS--The study comprised 88 subjects, aged 20-45 years, from the general population in Uppsala, a mid-Swedish urban community, selected by stratified random sampling. Room temperature, air humidity, respirable dust, carbon dioxide (CO2), VOCs, formaldehyde, and house dust mites were measured in the homes of the subjects. They underwent a structured interview, spirometry, peak expiratory flow (PEF) measurements at home, methacholine provocation test for bronchial hyperresponsiveness, and skin prick tests. In addition, serum concentration of eosinophilic cationic protein (S-ECP), blood eosinophil count, and total immunoglobulin E (S-IgE) were measured. RESULTS--Symptoms related to asthma were more common in dwellings with house dust mites, and visible signs of dampness or microbial growth in the building. Significant relations were also found between nocturnal breathlessness and presence of wall to wall carpets, and indoor concentration of CO2, formaldehyde, and VOCs. The formaldehyde concentration exceeded the Swedish limit value for dwellings (100 micrograms/m3) in one building, and CO2 exceeded the recommended limit value of 1000 ppm in 26% of the dwellings, showing insufficient outdoor air supply. Bronchial hyperresponsiveness was related to indoor concentration of limonene, the most prevalent terpene. Variability in PEF was related to two other terpenes; alpha-pinen and delta-karen. CONCLUSION--Our results suggest that indoor VOCs and formaldehyde may cause asthma-like symptoms. There is a need to increase the outdoor air supply in many dwelling, and wall to wall carpeting and dampness in the building should be avoided. Improved indoor environment can also be achieved by selecting building materials, building construction, and indoor activities on the principle that the emission of volatile organic compounds should be as low as reasonably achievable, to minimise symptoms related to asthma due to indoor air pollution.

The "sick building syndrome" involves symptoms such as eye, skin and upper airway irritation, headache, and fatigue. A multifactorial study was performed among personnel in consecutive cases of sick buildings to investigate relationships between such symptoms, exposure to environmental factors, and personal factors. The total indoor hydrocarbon concentration was significantly related to symptoms. Other indoor exposures such as room temperature, air humidity, and formaldehyde or carbon dioxide concentration did not correlate with the symptoms. Personal factors such as reported hyperreactivity and sick leave due to airway diseases were strongly related to the sick building syndrome. Other factors associated with the sick building syndrome were smoking, psychosocial factors, and experience of static electricity at work. Neither atopy, age, sex, nor outdoor exposures correlated significantly with the number of symptoms. It was concluded that the sick building syndrome is of multifactorial origin and related to both indoor hydrocarbon exposure and individual factors.