Decreased Respiratory Symptoms After Intervention in Artificially Ventilated Offices in São Paulo, Brazil

occupational and environmental lung disease Decreased Respiratory Symptoms After Intervention in Artificially Ventilated Offices in Sa˜o Paulo, Brazil* Gustavo S. Graudenz, MD; Jorge Kalil, MD, PhD; Paulo H. Saldiva, MD, PhD, FCCP; Maria do Rosa´rio D. O. Latorre, PhD; and Fabio F. Morato-Castro, MD, PhD

Background: The increase in work-related respiratory complaints in artificially ventilated buildings have multiple causes, and intervention studies are a valuable approach to understanding possible mechanisms. Study objectives: To analyze the effects of an intervention in a ventilation system with > 20 years of continuous use, and with a high rate of building-related respiratory complains. Design: An epidemiologic study was done among individuals working in places with ventilation machinery and ducts with > 20 years of use, before and after intervention. Analysis of symptoms and logistic regression were performed to check the associations between air-conditioning intervention and reported symptoms. Results: The air-conditioning intervention showed a protective effect on building-related worsening of respiratory symptoms (odds ratio, 0.132; 95% confidence interval, 0.030 to 0.575), naso-ocular symptoms (odds ratio, 0.231; 95% confidence interval, 0.058 to 0.915), and persistent cough (odds ratio, 0.071; 95% confidence interval, 0.014 to 0.356). Conclusion: Intervention in high-risk occupational locations can be effective in improving perceived indoor air quality. (CHEST 2004; 125:326 –329) Key words: air conditioning; air pollution; indoor; intervention studies; occupational health Abbreviations: IAQ ⫽ indoor air quality; HVAC ⫽ heating, ventilation, and air conditioning

increasing number of complains and health A neffects related to time spent in artificially ventilated buildings have been reported during the last 30 years. Mucosa-related complaints such as nasal congestion, pharyngeal pruritus, persistent cough, wheezing, dry throat, and increased number of viral and bacterial infections are frequently reported in these populations.1 Considering that no single causative agent is commonly reported in cross-sectional *From the Division of Allergy and Clinical Immunology, Internal Medicine Department (Drs. Graudenz, Kalil, and MoratoCastro), and Department of Pathology (Dr. Saldiva), School of Medicine; and Department of Epidemiology (Dr. Latorre), School of Public Health, University of Sa˜o Paulo, Sa˜o Paulo, Brazil. This work was performed at University of Sa˜o Paulo, Sa˜o Paulo, Brazil. This work was partially supported by grants obtained from the following Brazilian institutions: Laborato´rio de Investigac¸a˜o Me´dica do Hospital das Clı´nicas da Faculdade de Medicina da 326

or prospective studies,2 the role of protective and improvement measures is still a matter of debate. We have previously reported an association between upper airway symptoms and places with heating, ventilation, and air conditioning (HVAC) systems with ⬎ 20 years of continuous use, but no improvement measures were mentioned.3 After the evaluaUniversidade de Sa˜o Paulo (Medical Investigation Laboratory of the Clinics Hospital of the School of Medicine of the University of Sa˜o Paulo), Fundac¸a˜o de Amparo a Pesquisa do Estado de Sa˜o (Sa˜o Paulo State Research Support Foundation), Conselho Nacional de Pesquisa (National Research Council), and Programa de Nacional de Exceleˆncia (National Excellence Program). Manuscript received December 4, 2002; revision accepted May 20, 2003. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (e-mail: [email protected]). Correspondence to: Gustavo S. Graudenz, MD, Rua Heitor Penteado 477, Sa˜o Paulo, Brazil 05437– 000; e-mail: gustavog@ usp.br Occupational and Environmental Lung Disease

tion, the HVAC system with the highest rate of health complaints was renovated and the same population returned to the studied place. After reoccupation, the population was reassessed to evaluate the modifications in the perceived indoor air quality (IAQ). Materials and Methods The studied office is located on the 35th floor of a building located in the downtown area of Sa˜ o Paulo. It has artificial illumination during daytime and is fully carpeted. The equipment used by the studied group consisted of individual video displays, one photocopy machine, five laser printers, five fax machines, and a self-service coffee machine. All of this equipment was replaced after renovation, except for the addition of another laser printer. The epidemiologic survey was based on a self-administered questionnaire regarding atopy, smoking status, respiratory symptoms, diagnosis of previous asthma or rhinitis, and work relation of the respiratory symptoms. The questionnaire was a combination of two previously standardized questionnaires validated for Portuguese language: the American Thoracic Society Division of Lung Diseases 78 questionnaire,4 and the International Study of Asthma and Allergies in Childhood questionnaire.5 The questions about asthma symptoms were as follows: Did you have wheezing or whistling in your chest in the last 12 months when you did not have a flu? Have you ever had attacks of shortness of breath with wheezing? The core questions about nasal symptoms were as follows: In the past 6 months, have you had a problem with sneezing, or a runny or a blocked nose when you did not have a flu? In the past 6 months, has this nose problem been accompanied by itchy-watery eyes? The question about sinus symptoms was as follows: In the last 12 months, did you have sinusitis (purulent nasal discharge accompanied by sinus pain and fever)? The question about upper respiratory infection was as follows: How many flu-like episodes did you have in the last 12 months. The question about persistent cough was as follows: Do you have daily coughs for ⬎ 3 weeks every year? The question about where

the symptoms were perceived was as follows: Where were the above symptoms more frequently evoked? The questionnaire was applied before and after the renovation of the air-conditioning system to the population of 23 subjects working in the studied place, and the occupational medical advice was to use antihistamines on an as-needed basis. Questions concerning sinusal and naso-ocular symptoms were considered as related to upper airways, whereas questions about wheezing and breathlessness were considered as related to the lower airways. The renovation of the HVAC system (Hitachi; Tokyo, Japan) [self-type, 10 tons of refrigeration] consisted of exchanging the ventilation ducts, and cleaning and maintenance of the ventilation machinery. There was an internal rearrangement of the office desks and exchange of the carpets and coverings as well. The renovations were done simultaneously, and the office was reoccupied 3 months after the work was initiated. Reassessment of the symptoms was done in September of 2002 (spring in Brazil), 14 months after the initial survey, which was done in July of 2001 (winter in Brazil). The control group was the population working in the same company, with the same office design, similar jobs, and with the same HVAC system but with ⬍ 2 years of continuous use, interrogated on the initial study. The population-reported symptoms before and after the air-conditioning renovation were compared using McNemar tests and after intervention and control using ␹2 tests. Univariate and multiple logistic regressions were used to analyze the effect of the air-conditioning renovation on naso-ocular, chest wheezing, sinus symptoms, persistent cough, and building-related worsening of self-stated symptoms. The symptoms were the outcome variables, and the control variables were gender, age, accumulated work time, smoking habits, passive smoking, history of familiar atopy, previous medical diagnosis of asthma and rhinitis, and the ventilation system groups. The Hosmer and Lemeshow tests were used to evaluate the goodness of fit of the model.

Results The questionnaire response rate for the before and after survey was 78%, totaling 18 of the available

Figure 1. Percentage of reported respiratory and building-related symptoms in control, before (pre), and after (post) air-conditioning renovation. *p ⬍ 0.05 in differences between before and after air-conditioning renovation-related symptoms. www.chestjournal.org

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Table 1—Renovation of the Ventilation System as a Related Factor for Respiratory Symptoms* Outcomes

OR Crude

95% CI OR Crude

OR Adjusted†

95% CI Adjusted OR†

H-L

Building-related worsening Naso-ocular symptoms Wheezing Persistent cough Breathlessness Sinusitis Frequent upper airway infections

0.132 0.231 1.523 0.071 2.428 0.400 0.438

0.030–0.575 0.058–0.915 0.290–8.011 0.014–0.356 0.386–15.272 0.104–1.544 0.069–2.762

0.059 0.085 0.186 0.083 2.372 0.294 0.399

0.005–0.647 0.012–0.609 0.014–2.410 0.016–0.438 0.318–17.682 0.049–1.757 0.031–5.070

0.803 0.656 0.750 0.505 0.458 0.995 0.331

*OR ⫽ odds ratio; CI ⫽ confidence interval; H-L ⫽ Hosmer-Lemeshow. †Adjusted by accumulated work time, smoking habits, and gender.

population of 23 subjects (50% male, 38.9% female, and 11.1% who chose to remain anonymous). The comparison of symptoms before and after renovation showed a reduction of naso-ocular symptoms (nasal pruritus, congestion, or water discharge concomitant with itchy-watery eyes), persistent cough, and workrelated worsening of the respiratory symptoms. Work-related symptoms consisted of blocked, runny, or itching noses in all subjects, and accompanied by itchy-watery eyes in 76.5% of this subset of the population. There was no significant difference between postintervention and control groups, showing a reduction of all symptoms to the basal level (Fig 1). The logistic regression showed a protective effect of the air-conditioning renovation, in the univariated and in the multivariated model adjusted by gender, accumulated work time, and smoking habits. There was a clear association of improvement of upper airway symptoms with air-conditioning renovation, but no effect was observed on the number of reported upper airway infections (Table 1). Discussion Since it was not possible to blind the participants of the study, there is a potential Hawthorne effect, due to a positive psychological impact of renovation of the air-conditioning system. However, if a positive psychological impact of the air-conditioning renovation existed, one should have expected it to have affected all types of symptoms and not only those from the upper airways. Measuring the symptoms by a self-administered questionnaire is also a potential limitation of this study. The use of questionnaires in assessing indoor air quality is still largely used in most studies of sick-building syndrome because there is a wide range in the threshold of response in any population, and a wide spectrum of response to any given agent.2 This study is a follow-up to a previous study,6 in which a detailed evaluation on airborne fungi, mite, 328

animal dander, and insect allergen exposure was performed. Although the aging of the ventilation system could lead to biological contamination,6 no significant biological or allergenic significant exposure was found.3 Considering that pollen exposure in Sa˜ o Paulo is clinically irrelevant,7 and the allergenic level found on the carpet was clinically insignificant, the allergenic exposure in this scenario was disregarded. The atopic individuals were considered a risk group for indoor air-related complaints. This apparent controversy is quite common in epidemiologic and occupational studies.8,9 We also found that places with ventilation systems with poor control of thermic parameters are at risk for work-related symptoms. Considering that atopic individuals have a decreased capacity to warm the inspired air,10 and the potential degranulation effect on mast cells of the cold and dry air,11 this could partially explain the atopy-related complaints in the absence of significant allergen exposure. IAQ-related problems are complex and multifactorial, involving multiple indoor pollutants, such as endotoxins, volatile organic compounds, particulate mater, and other indoor and outdoor pollutants. In spite of the fact that they could influence the perceived quality of the indoor air, the routine investigation of all these factors is considered expensive and not elucidative.12 In the present study, the prevalence of most building-related symptoms decreased substantially after the renovation of the air conditioning, and the respiratory complaints dropped to control levels. Previously reported conservative intervention studies8,13 to improve IAQ failed to demonstrate significant improvements. Our results are in agreement with the concept that “cleanliness is next to healthiness,”14 specifically of the upper airways in this context. IAQ is considered a major public health concern, and the efforts to produce cost-effective interventions are a current priority in occupational health. Occupational and Environmental Lung Disease

Controlled experiments on simulated work places and cohort studies in population samples living under artificial ventilation systems may bring further understanding of how to prevent and improve indoor air-related occupational health. ACKNOWLEDGMENT: We thank Alexandre T. Rotta, MD, for review of the manuscript.

References 1 Bardana EJ Jr, Montanaro A, O’Hollaren MT. Buildingrelated illness: a review of available scientific data. Clin Rev Allergy 1988; 6:61– 89 2 Menzies D, Bourbeau J. Building-related illnesses. N Engl J Med 1997; 337:1524 –1531 3 Graudenz GS, Kalil J, Saldiva PH, et al. Upper respiratory symptoms associated with aging of the ventilation system in artificially ventilated offices in Sao Paulo, Brazil. Chest 2002; 122:729 –735 4 Ferris BG. Epidemiology Standardization Project (American Thoracic Society). Am Rev Respir Dis 1978; 118:1–120 5 Asher MI, Keil U, Anderson HR, et al. International Study of Asthma and Allergies in Childhood (ISAAC): rationale and methods. Eur Respir J 1995; 8:483– 491

www.chestjournal.org

6 Oliver LC, Shackleton BW. The indoor air we breathe. Public Health Rep 1998; 113:398 – 409 7 Polinose ME. In alergia no Brasil. 1st ed. Sa˜ o Paulo, Brazil: Manole Publishers, 1989; 67– 86 8 Menzies D, Pasztor J, Rand T, et al. Germicidal ultraviolet irradiation in air conditioning systems: effect on office worker health and wellbeing: a pilot study. Occup Environ Med 1999; 56:397– 402 9 Ooi PL, Goh KT, Phoon MH, et al. Epidemiology of sick building syndrome and its associated risk factors in Singapore. Occup Environ Med 1998; 55:188 –193 10 Rouadi P, Baroody FM, Abbott D, et al. A technique to measure the ability of the human nose to warm and humidify air. J Appl Physiol 1999; 87:400 – 406 11 Togias AG, Naclerio RM, Proud D, et al. Nasal challenge with cold, dry air results in release of inflammatory mediators: possible mast cell involvement. J Clin Invest 1985; 76: 1375–1381 12 Bardana EJ, Jr. Sick building syndrome: a wolf in sheep’s clothing. Ann Allergy Asthma Immunol 1997; 79:283–293 13 Kildeso J, Wyon D, Skov T, et al. Visual analogue scales for detecting changes in symptoms of the sick building syndrome in an intervention study. Scand J Work Environ Health 1999; 25:361–367 14 Raw G, Roys MS, Whitehead C. Sick building syndrome: cleanliness is next to healthiness. Indoor Air 1993; 3:237–245

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