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作者：Jacquelyn K. Beals, PhD  
出處：WebMD醫學新聞

　　December 16, 2009（阿根廷布宜諾斯艾利斯）－一項比較於封密閉人造換氣與自然通風建築物內工作參與者發生過敏性鼻炎盛行率的巴西研究發現，鼻炎與扎皮膚測試結果不一，但是兩組之間無顯著差異。
　　
　　Rio de Janeiro聯邦大學Clementino Fraga Filho大學醫院胸腔疾病機構的Jose Luiz de Magalhaes Rios博士在世界過敏組織第21屆世界過敏會議平台發表會上表示，越來越多人花很多的時間待在僅仰賴密閉人造換氣作為氣體交換機轉的建築。如果氣體交換比例低，汙染物質會蓄積在建築物中。然而，室內汙染物質的角色仍然未明。
　　
　　目前這項研究檢驗在Rio de Janeiro城區兩個不同建築工作人員發生過敏性鼻炎的關係，一個是密閉建築、一個是自然換氣建築，它們的整體揮發性有機化合物（TVOCs）的空氣濃度不同。
　　
　　研究者們研究7~14樓的全職工作人員，超過街道汙染物質直接影響的樓層。於不同天收集8小時的樣本，對這些樓層進行空氣品質分析，確認了這些密閉建築樓層的TVOC濃度超過建議值（500 μg/m3）。其中三個樓層超過1000 μg/m3。在自然換氣的建築中，所有納入的樓層TVOC濃度都低於250 μg/m3。
　　
　　在密閉建築共有210位（總數有292位），而在非密閉建築有186位（總共有296位）。每位參與者都完成兒童氣喘與免疫國際研究（ISAAC）鼻炎問卷、完成一項醫學檢查、及接受札皮膚測試來確認對歐洲塵螨（家庭塵螨）、熱帶無爪螨（一種倉庫塵螨）、煙麴黴（一種常見黴菌）、美洲蟑螂（一種美洲蟑螂）的感受性。
　　
　　過敏性鼻炎病例認定需要ISAAC問卷3分以上，有鼻炎7個臨床病徵與3個以上的症狀（打噴嚏、鼻塞、鼻子癢、鼻炎、鼻黏膜蒼白、鼻甲過度增生、鼻透明分泌物），一次以上的扎皮膚測試陽性，以符合研究之過敏性鼻炎的定義。
　　
　　Rio博士向Medscape過敏與免疫學表示，在臨床檢查中，非密閉建築物的參與者中，有一個症狀比較常見。非密閉建築物的參與者中，鼻（鼻甲）過度增生比較常見，而密閉建築物的參與者中，較常見扎皮膚測試結果呈陽性。
　　
　　兩組之間在鼻甲過度增生的盛行率達到統計上差異（P=0.006），在密閉建築物的參與者有48.6%，非密閉建築物有62.4%。相反的，密閉建築物的參與者札皮膚測試比較容易偏向陽性反應，P值從0.009到0.04。這兩組ISAAC問卷結果並無顯著差異（P=0.25）。
　　
　　因為必須要符合所有三個條件才能符合過敏性鼻炎診斷，這些結果相互抵消，確認出密閉建築內有19.5%、非密閉建築物內有20.4%工作人員罹患過敏性鼻炎，這之間的差異並未達到統計上顯著水準（P=0.82）。
　　
　　當被問到他可能如何改變研究設計來釐清結果，Rios博士向Medscape過敏與免疫學表示，這是個很困難的問題。但這項研究基本上是比較兩個建築物，且現在很難找到非密閉建築。Rio博士表示，我想目標將會是在一年期間報告三次在這兩棟建築內的人們，看症狀盛行率是否有任何改變。且對於一開始對一種反應有敏感性的人們，1或2年後會有什麼改變。
　　
　　在闡釋這些結果上有一個困難是，這兩棟建築物的流行病學差異。在密閉建築物，參與者中有58.1%是男性，平均年齡為40.67歲，且最大的一群工作人員（48.1%）被歸類為「專業工作人員」。在非密閉建築中，參與者中有33.9%為男性，平均年齡為47.11歲，但絕大多數（42.1%）被歸類為「其他類別」，非管理、專業或是辦公室/秘書職員。
　　
　　座談會共同引言人，來自巴塞隆納Biomediques August Pi i Sunyer 研究機構醫院診所ENT部門的Joaquim Mullol醫師在與Medscape過敏與免疫學對談時說到，這項研究一個重要的問題是，你必須控制許多事情，以確認兩組之間在這些建築物中生活或是工作的內容相符，因為有時候他們並不一致，且這在最終的報告中造成很大的差異。
　　
　　Mullol醫師表示，那就是為什麼這類研究並不容易進行，比較兩組的差異在方法學上是很困難的；這是這項研究中最重要的議題，而要達到這個目的是非常困難且須花費很多錢的。當被問到文獻上其他研究是否有報告比較密閉與非密閉建築物比較結果時，Mullol醫師回答，據我所知目前並沒有這樣的研究，相對於過敏，我並非這個領域的專家，但這個是應該被展現出來的議題。
　　
　　Mullol醫師觀察到，我們必須得到針對過敏或汙染物質設計嚴謹的研究結果。我們有許多來自戶外汙染物質的研究結果，但是來自室內的汙染物質，我們的資料並不多，我們需要進行更多的研究。
　　
　　Rios博士與Mullol醫師表示已無相關資金上的往來。


Volatile Organic Compounds in Buildings Linked to Allergic Rhinitis

By Jacquelyn K. Beals, PhD
Medscape Medical News

December 16, 2009 (Buenos Aires, Argentina) — A Brazilian study comparing the prevalence of allergic rhinitis in people working in sealed artificially ventilated buildings and those working in buildings with natural ventilation found variations in the occurrence of rhinitis and positive skin-prick tests, but no significant difference overall between the 2 groups.

More people are spending significant amounts of time in sealed buildings with artificial ventilation systems as the only mechanism of air exchange, noted Jose Luiz de Magalhaes Rios, PhD, from the Institute of Thoracic Diseases, Clementino Fraga Filho University Hospital, Federal University of Rio de Janeiro, in Brazil, in his platform presentation here at the World Allergy Organization XXI World Allergy Congress. If the rate of air exchange is low, pollutants accumulate in the buildings. However, the role of indoor pollution is not well understood.

The current study explored the association between the occurrence of allergic rhinitis in office workers in 2 buildings in downtown Rio de Janeiro — one sealed and the other with natural ventilation — that differed in their air concentration of total volatile organic compounds (TVOCs).

The investigators studied full-time office personnel working between the seventh and fourteenth floors, above any direct influence of street pollutants. Air quality analyses on these floors, using samples collected for 8 hours on 2 different days, determined that TVOC levels on all included floors of the sealed building exceeded the recommended level (500?μg/m3). Three floors exceeded 1000?μg/m3. In the building with natural ventilation, TVOC concentrations on all included floors were less than 250?μg/m3.

Participants were 210 (of 292) workers in the sealed building and 186 (of 296) workers in the nonsealed building. Each participant completed the International Study on Asthma and Allergies in Childhood (ISAAC) rhinitis questionnaire, had a medical examination, and underwent skin-prick tests to determine sensitivity to Dermatophagoides pteronyssinus (the house dust mite), Blomia tropicalis (a storage mite), Aspergillus fumigatus (a common mold), and Periplaneta americana (the American cockroach).

A case of allergic rhinitis required a score of 3 or higher on the ISAAC questionnaire, the presence of at least 3 of 7 clinical signs and symptoms of rhinitis (sneezing, nasal obstruction, nasal pruritus, coryza, pallor of nasal mucosa, hypertrophy of turbinates, and hyaline nasal secretion), and 1 or more positive skin-prick tests to meet the study definition of allergic rhinitis.

"In the clinical examination, there was 1 symptom more prevalent in the nonsealed building," Dr. Rios told Medscape Allergy and Immunology. "Nasal [turbinate] hypertrophy was more prevalent in the nonsealed building, and the [positive] skin-prick test was more prevalent in the sealed building."

The difference between the 2 groups in prevalence of turbinate hypertrophy was highly significant (P?= .006), with 48.6% of participants affected in the sealed building and 62.4% affected in the nonsealed building. Conversely, skin-prick tests consistently differed in the direction of more positive reactions in the sealed building, with P?values ranging from .009 to .04. Results of the ISAAC questionnaire did not differ significantly between the 2 groups (P?= .25)

Because participants had to meet all 3 criteria to be diagnosed with allergic rhinitis, the results balanced out, identifying 19.5% of workers in the sealed building and 20.4% of workers in the nonsealed building as having allergic rhinitis, a nonsignificant difference (P?= .82).

Asked how he might change the study to clarify the results, Dr. Rios told Medscape Allergy and Immunology: "It's a difficult question. But the design was basically comparing 2 buildings, and nowadays it's most difficult to find nonsealed buildings. I think that the goal would be to make a report of people in these 2 buildings 3 times in a 1-year interval to see if there are any changes in the prevalence of symptoms. And for people who responded with one type of response at the beginning, how they would be 1 or 2 years later," said Dr. Rios.

One difficulty in interpreting the results was the different demographics in the 2 buildings. In the sealed building, participants were 58.1% male, had a mean age of 40.67 years, and had the largest proportion of workers (48.1%) classified as "professional." In the nonsealed building, participants were 33.9% male, had a mean age of 47.11 years, and had the largest proportion of workers (42.1%) classified as "other" — not managerial, professional, or clerical/secretarial.

"One of the main problems with this study is that you have to have everything very well controlled?.?.?. to be sure that both groups of people living or working in these buildings match, because sometimes they don't match?.?.?. and that can make a lot of difference in the final account," said session comoderator Joaquim Mullol, MD, PhD, from the ENT Department, Hospital Clinic, Institut d'Investigacions Biomediques August Pi i Sunyer, in Barcelona, Spain, talking with Medscape Allergy and Immunology.

"That's why it's not easy to do this kind of a study.?.?.?. Comparing 2 groups is very difficult methodology; it is the most important issue in this study, and it's very difficult and expensive to do," said Dr. Mullol. Asked whether other studies in the literature had reported results from comparisons of sealed and nonsealed buildings, Dr. Mullol replied: "Not as far as I know, relative to allergy. I'm not an expert in that field, but it's an issue that should be demonstrated."

"We need to?.?.?. get good studies on either allergens or pollutants. We have some data from external pollutants?.?.?. but we have very few good data from inside buildings, and we need to do many more studies on that," observed Dr. Mullol.

Dr. Rios and Dr. Mullol have disclosed no relevant financial relationships.

World Allergy Organization XXI World Allergy Congress (WAC): Abstract?707. Presented December?8, 2009.