SICK BUILDING SYNDROME: INDOOR POLLUTANTS LEVELS AND PREVALENCE OF SYMPTOMS AMONG WORKERS OF A SEALED OFFICE BUILDING.

Transcription

1 SICK BUILDING SYNDROME: INDOOR POLLUTANTS LEVELS AND PREVALENCE OF SYMPTOMS AMONG WORKERS OF A SEALED OFFICE BUILDING. JL Boechat 1, JL Rios 1*, T Freitas 2, CY Santos 2, JR Lapa e Silva 1, FR Aquino Neto 2 1 Institute of Thoracic Diseases/Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, Brazil. 2 Lagoa - Ladetec, Organic Chemistry Department / Chemistry Institute, Federal University of Rio de Janeiro, Brazil. ABSTRACT To evaluate the association of work-related symptoms with the concentration of the main indoor pollutants, a self-administered questionnaire was given to 1736 office workers of a 42 storey sealed building. Indoor pollutants were measured in 7 selected floors. Standardized international methodologies were used to investigate the indoor concentration of CO 2, aerodispersoids and volatile organic compounds. Upper respiratory symptoms presented a great prevalence, around 40%, whereas lower airways manifestations frequencies were below 20%. The most prevalent symptoms were tiredness and headache, over 50%, although these were the least improved symptoms out of the work place. Nasopharyngeal and ophthalmic manifestations seem to be the more affected by the internal environment, for they present the highest indices of improvement out of the workplace. The building s levels of CO 2, aerodispersoids and TVOCs were higher than the recommended. The great prevalence of Sick Building Syndrome symptoms may be related to the levels of indoor pollutants. INDEX TERMS Sick building syndrome, office work, air quality, respiratory symptoms, indoor pollutants. INTRODUCTION Modern man spends much of his daily life in enclosed places, above all in the workplace. An increasing number of complaints and health effects related to time spent in artificially ventilated buildings have been reported during the last 30 years. Problems associated with the indoor environment are the most common environmental health issues faced by clinicians, but the factors associated with the perceived indoor air quality are not fully understood. The indoor environment affects the occupants, mainly by means of the air. Contaminant agents, whether volatile or in suspension, enter into direct contact with the occupants through the skin and the eyes, nose and lungs mucosae (Samet et al 1998). In Brazil, as in other tropical countries, there is growing concern with regard to the increasing utilization of heating, ventilation, and air conditioning (HVAC) systems in sealed buildings, drawing the attention of researchers from several areas and of the Ministry of Health (Brickus and Aquino Neto 1999, Ministerio da Saude 2000, Graudenz et al. 2004). Sealed buildings with air conditioning systems usually present high pollutant levels due to the low internal/external air exchange rate, in addition to diverse materials used in linings, finishing and furniture that contain various types of volatile chemical substances. The set of health problems related to the internal environment of non-industrial, non-residential buildings, the majority of which are office blocks, are denominated building related illnesses (BRI) (Menzies and Bourbeau 1997). The BRI are considered specific when characterized by objective abnormalities under clinical and laboratorial evaluation, with a well-defined causal agent. They are non-specific when they refer to a heterogeneous group of * Corresponding author jlrios@globo.com 3711

2 symptoms: respiratory, cutaneous, ocular or even ill defined, such as headache, fatigue and difficulty of concentration, related to the work environment (Brickus and Aquino Neto 1999, Menzies and Bourbeau 1997, Meggs 2002, Bardana and Montanaro 1991). Factors contributing to perceived indoor air quality include temperature, humidity, odors, air movement and ventilation, and bioaerosol and volatile organic compounds (VOCs) contamination (Apter et al 1994). However, concentrations of single pollutants have not been shown to consistently associate with symptoms in observational studies. Studies that attempt to associate occupant symptoms and total VOC (TVOC) levels report inconsistent findings, just like the researches concerning workers symptoms and total suspended particles (TSP). (Skyberg et al 2003) In Brazil, Graudenz et al found a strong association of building-related upper-airway symptoms with places having ventilation systems with > 20 years of use, although it was impossible to associate these symptoms with allergen exposure in the workplace environment (Graudenz et al 2002). Various international studies have sought to evaluate the prevalence of BRI symptoms. With the aim of standardising the diagnosis and enabling comparison between different studies, the Royal Society of Health Advisory Group on Sick Building Syndrome has developed a standard questionnaire (Raw 1995). The aim of this study was to investigate if work-related symptoms (Sick Building Syndrome SBS), assessed by a standardized questionnaire, could be related to the concentration of the main indoor pollutants, in office workers of a sealed building in a tropical city. RESEARCH METHODS Cross-sectional study involving 1,736 full-time office workers in a 42-storey office building with 30 years of commercial use, located in the downtown area of Rio de Janeiro, Brazil. The building was totally sealed, with HVAC systems without opening windows. None of the selected places was at the ground level, varying from the 3 rd to the 37 th floor. In the building, all offices were fully carpeted and were equipped with fax machines, laser printers and video terminal displays. After the authorization of the building administration, a self-administered questionnaire about SBS elaborated by The Royal Society of Health Advisory Group, translated to Portuguese and validated, was applied to the workers to determine the prevalence of respiratory and nonspecific symptoms. Temperature, humidity, air movement and indoor pollutants were measured in 7 selected floors. Standardized international methodologies were used to investigate the indoor concentration of CO 2 (Gas analysis/infrared sensor), aerodispersoids (Indoor air filtration through specific membrane using high volume), VOCs (High resolution gas chromatography, HRGC and HRGC coupled to Mass Spectrometry, HRGC-MS) and temperature, humidity and air movement (Thermo-hygrometer and Thermo-anemometer). EPI-INFO 6 software was used to perform the statistical analysis of the data. RESULTS Table 1. Population characteristics Response rate % Gender (male) % Mean Age (years) 39.9 yr 0.27 * Hours of work (p/week) 37.4 hr 0.42 * Type of work Managerial % Professional % Clerical /secretarial % Other % No answer % Smoking (active) % * standard error of mean 3712

3 The response rate was 55.7%, totalizing 967 responders of The characteristics of the population studied are presented in Table 1. Five of the 7 studied floors presented CO 2 levels above the recommended limit (1,000 ppm). Aerodispersoids concentration was higher than 80 µg/m 3 in 4 floors and TVOCs exceeded 500 µg/m 3 in 3 of the 7 floors (Table 2). Temperature, humidity and air movement did not exceeded the recommended limits. TVOCs levels per floor are illustrated in Figure 1. The group of individuals studied had a high prevalence of nasopharyngeal and ophthalmic symptoms: ocular itching in 395 (40.9%), stuffy nose in 501 (51.8%), runny nose in 361 (37.5%), and dry throat in 406 (42.2%). Lower airways symptoms such as chest wheezing or breathlessness episodes were less prevalence (8.3 and 20% respectively). Lethargy was present in 566 (58.7%) and headache in 537 (55.5%) of the employees (Table 3). Temperature Table 2. Indoor air quality analysis INDOOR AIR - FLOORS 37.º 36.º 34.º 25.º 17.º 4.º 3.º Limits* o C to 27 Humidity % to 65 Air m/s to 0.25 movement Aerodispersoids µg/m [CO2] ppm VOCs µg/m * Brickus and Aquino Neto, 1999; Ministério da Saúde, TVOCs ug/m Total concentration AQUINO NETO and BRICKUS MOLHAVE and CLAUSEN outdoor Floors Figure 1. TVOCs levels Table 3. Symptoms prevalence, improvement and frequency Prevalence Improvement Symptoms frequency n = 967 outside workplace More than once a week Less than once a week n.º % n.º % n.º % n.º % Dry eyes Ocular itching Stuffy nose Runny nose Dry throat Lethargy/Tiredness Headache

4 Dry, itching skin Breathlessness Chest tightness Wheezing DISCUSSION A predominance of males was observed in the sample studied, probably due to the characteristics of the institution evaluated: the head office of a major bank. The average number of hours of work per week was 37.4, which makes them susceptible to the influences of the internal environment. It s important to remember that all self-administered questionnaires can lead to bias. Workers experiencing more symptoms and perception of disease are more likely to complete the questionnaire. The low response rates in the studied population could be attributed to the size of the questionnaire, which demanded more time to be completed. A low response rate may result in relatively high prevalence of symptoms. There are other potential information biases such as job satisfaction, amount of work, job-related stress and other unknown job-related factors that could influence the outcomes (Crawford and Bolas 1996). The nasopharyngeal and ophthalmic manifestations, with a prevalence of around 40%, seem to be those that suffer a greater influence from the internal environment, for they present the highest indices of improvement when the worker is away from the workplace. It is important to highlight that the allergic rhinoconjuntivitis symptoms prevalence (ocular itchiness, watery eyes and runny nose), is twice as high in the population studied as that observed in the general population, indicating probable environment s influence on these symptoms (Wuthrich et al. 1995, Strachan et al. 1997, Bousquet et al. 2001). The lower airways manifestations are among the least prevalent in the study sample. The anatomical characteristics of the airways could explain this discrepancy between the nasal and bronchial symptoms. The nose mucosae, as the entrance to the respiratory system, is more exposed to volatile substances and inhalable particles, and the nose s configuration hinders progress of these substances toward the lower airways (Salvaggio 1994). The low prevalence of wheezing and other respiratory symptoms observed in the sample is similar to the prevalence of asthma in the general population (European Community Respiratory Health Survey 1996, Beasley et al. 1998, Boechat 2001, Rios 2001). Although occupational asthma is a classic condition described in the literature, there are no up-to-date references associating this ailment with the type of environment studied in this research (Bardana 2003). Among the other BRI symptoms evaluated, there was a predominance of the non-specific ones (lethargy/tiredness and headache). Such symptoms might be related to a low air exchange rate with the outdoor environment, reflected by CO 2 accumulation, or could be attributed to exposure to VOCs. (Molhave et al. 1986). They could also be associated to stress arising from the workloads. On the other hand, the low improvement index of these symptoms away from the workplace may signify that these are not only related to the quality of the indoor environment. Although the cutaneous manifestations are rarely ever considered as a significant complaint, they constitute around 25% of the symptoms detected in our study. The mechanisms involved in the cutaneous manifestations related to indoor environment are still not well defined, but reports of itching, skin redness and dryness are common (James 1994). CONCLUSION AND IMPLICATIONS The levels of CO2, aerodispersoids and TVOCs were greater than the recommended in the building. The improvement of symptoms outside of the workplace may suggest that this low indoor air quality may be related to the increasing of the prevalence of respiratory symptoms, mainly of the higher airways. A cohort study using a sample population during 18 months will be implemented to check this hypothesis. ACKNOWLEDGEMENTS Banco do Brasil, FUJB, CNPq and Capes 3714

5 REFERENCES Apter A., Bracker A., Hodgson M., Sidman J., Leung WY Epidemiology of the sick building syndrome J Allergy Clin Immunol. 94 (2): Bardana, EJ., Jr Occupational asthma and allergies, J. Allergy Clin. Immunol. 111:S530-S539. Bardana Jr EJ, Montanaro A Formaldehyde: an analysis of its respiratory, cutaneous and immunologic effects. Ann. Allergy Asthma Immunol.66: Beasley R., Keil U., Mutius E. et al Worldwide variation in prevalence of symptoms of asthma, allergic rhinoconjuntivitis, and atopic eczema: ISAAC. Steering Committee, The Lancet 351: Boechat JL Avaliação da prevalência e gravidade da asma em escolares no município de Duque de Caxias, RJ, M.D. Thesis, Federal University of Rio dejaneiro (Brazil),143 pages. Bousquet J., Van Cauwenberge P. and Khaltaev, N Allergic rhinitis and its impact on asthma, J. Allergy Clin. Immunol. 108:S147-S334. Brickus LSR, Aquino Neto FR A qualidade do ar de interiores e a química. Química Nova;22: Crawford JO. and Bolas SM Sick building syndrome, work factors and occupational stress, Scand. J. Work Environ. Health. 22: European Community Respiratory Health Survey Variations in the prevalence of respiratory symptoms, self-reported asthma attacks, and use of asthma medication in the European Community Respiratory Health Survey (ECRHS), Eur. Respir. J. 9: Graudenz GS., Kalil J. et al Upper respiratory symptoms associated with aging of the ventilation system in artificially ventilated offices in Sao Paulo, Brazil, Chest 122: Graudenz GS., Oliveira CH., Tribess A., Latorre MRDO., Mendes Jr C, Kalil J Association of air-conditioning with respiratory symptoms in office workers in tropical climate. Indoor Air 15: Meggs WJ Sick building syndrome, chemical sensitivity and irritant rhinosinusitis. J Allergy Clin Immunol. 109: S51, Abstract 105. Menzies D, Bourbeau J Building-related illnesses. NEJM. 337: Ministério da Saúde. Agência Nacional de Vigilância Sanitária. Resolução RE n 176, Molhave L., Bach R. and Pederson OF Human reactions to low concentrations of volatile organic compounds, Environ. Int. 12: Raw GJ A questionnaire for studies of sick building syndrome. A report to The Royal Society of Health Advisory Group on sick building syndrome. In: Raw GJ, editor. Building Research Establishment Report. 1a. ed. London: Construction Research Communications Ltd; p 1-9. Rios JL Prevalência de asma em escolares e poluição atmosférica em dois municípios do Rio de Janeiro, M.D. Thesis, Federal University of Rio de Janeiro (Brazil),137 pages. Salvaggio, JE Inhaled particles and respiratory disease, J. Allergy Clin. Immunol. 94: Samet JM., Spengler JD., Mitchell C.S Indoor air pollution. In: Rom WN, editor. Environmental and Occupational Medicine. 3a ed. Philadelphia: Lippincott- Raven. p Skyberg K, Skulberg KR, Eduard W, Levy F, Sk_ret E, Kjuus H Symptoms prevalence among office employees and associations to building characteristics. Indoor Air. 13: Strachan D., Sibbald B., Weiland S. et al Worldwide variations in prevalence of symptoms of allergic rhinoconjunctivitis in children: the International Study of Asthma and Allergies in Childhood (ISAAC), Pediatr. Allergy Immunol. 8: Wuthrich B., Schindler C., Leuenberger P. et al Prevalence of atopy and pollinosis in the adult population of Switzerland (SAPALDIA study). Swiss Study on Air Pollution and Lung Diseases in Adults, Int. Arch. Allergy Immunol.106: