Despite decades of indoor smoking bans and restrictions， new research from Drexel University suggests the toxins we’ve been trying to keep out are still finding their way into the air inside. Findings by a group of environmental engineers show that third-hand smoke， the chemical residue from cigarette smoke that attaches to anything and anyone in the vicinity of a smoke cloud， can make its way into the air and circulate through buildings where no one is smoking.

室內(nèi)吸煙禁限令已實施數(shù)十年。不過，德雷塞爾大學的最新研究表明，雖然我們一直努力將煙草毒素拒之門外，但這些毒素仍然能夠進入室內(nèi)空氣。環(huán)境工程師們的研究結果顯示，三手煙能在無人吸煙的建筑內(nèi)潛入空氣，進行室內(nèi)循環(huán)。三手煙是指附著在煙團附近任何人或物上面的煙草煙霧化學殘留物。

The study， which was recently published in the journal Science Advances， further clarifies our understanding of just how pervasive the toxic chemicals of cigarette smoke can be—even in a “smoke-free” indoor environment.

該研究成果不久前發(fā)表于《科學進展》雜志，讓人們進一步認清了煙草煙霧有毒化學物質(zhì)的傳播范圍——即便是“無煙”的室內(nèi)環(huán)境也無法幸免。

“While many public areas have restriction on smoking， including distance from doorways， non-smoking buildings and even full smoking bans on campus for some universities， these smoking limitations often only serve to protect non-smoking populations from exposure to second-hand smoke，” said Michael Waring， PhD， an associate professor in Drexel’s College of Engineering， and a co-author of the research. “This study shows that third-hand smoke， which we are realizing can be harmful to health as with second-hand smoke， is much more difficult to avoid.”

德雷塞爾大學工程學院副教授、該研究成果共同作者之一邁克爾·韋林博士表示：“雖然許多公共區(qū)域都有吸煙限制，比如吸煙區(qū)要與門口保持距離、樓內(nèi)禁止吸煙、一些大學實行校園內(nèi)全面禁煙，但這些限制往往只能保護非吸煙人群免受二手煙的危害。該研究顯示，避開三手煙的難度要大得多，而我們逐漸意識到三手煙和二手煙一樣對健康有害。”

Peter DeCarlo， PhD， an atmospheric chemist at Drexel， teamed up with Waring， whose research focuses on indoor air quality， on this National Science Foundation-funded work that revealed the new pathway of exposure to third-hand smoke.

德雷塞爾大學大氣化學家彼得·德卡洛博士與專事室內(nèi)空氣質(zhì)量研究的韋林博士攜手，完成了這一由美國國家科學基金會資助的項目，揭開了此前未曾發(fā)現(xiàn)的三手煙接觸途徑。

“Aerosol particles are ubiquitous particles suspended in the air—they come from a variety of sources and are known to be detrimental to health，” DeCarlo said. “The fact that third-hand smoke can attach to them， like it would to the clothing or furniture of a smoker， means that the potentially toxic chemicals associated with third hand smoke are found in places we wouldn’t have expected.”

“氣溶膠顆粒是懸浮于空氣中的微粒，幾乎無處不在。這些微粒來源廣泛，據(jù)知對人體健康有害?！钡驴宀┦拷忉尩?，“三手煙能附著在氣溶膠顆粒上，正如它會吸附在吸煙者的衣物或家具上，這意味著與其相關的潛在有毒化學物質(zhì)會出現(xiàn)在我們意想不到的任何地方?！?/p>

A surprise inside

室內(nèi)的“意外發(fā)現(xiàn)”

Anita Avery， PhD， a doctoral student working with DeCarlo was studying the transport of particles from outdoors to indoors by monitoring these particles inside an unoccupied， non-smoking classroom. The composition of these particles， measured by an aerosol mass spectrometer over the course of several weeks， provided a detailed look at the chemical differences between outdoor and indoor particles in the air.

安妮塔·埃弗里博士在德卡洛指導下攻讀博士學位期間，曾通過監(jiān)測一個閑置的無煙教室內(nèi)的顆粒物狀況，來研究顆粒物從室外到室內(nèi)的傳播。數(shù)周時間里，她借助氣溶膠質(zhì)譜儀對這些顆粒物的成分進行了檢測，詳細考察了室內(nèi)外空氣中顆粒物的化學差異。

What they found was eye-opening.

研究發(fā)現(xiàn)令人大開眼界。

“In an empty classroom， where smoking has not been allowed in some time， we found that 29 percent of the entire indoor aerosol mass contained third-hand smoke chemical species. This was obviously quite startling and raised many questions about how that much third-hand smoke could be lingering in a non-smoking， ventilated room，” Avery said.

埃弗里表示：“教室是空的，已經(jīng)禁煙一段時間，但我們發(fā)現(xiàn)，29%的室內(nèi)氣溶膠含有三手煙化學物質(zhì)。這著實令人震驚，引發(fā)了很多問題——在這樣一個無煙且通風的房間里，三手煙為何難以絕跡？”

To investigate the cause of this surprising finding， Avery and DeCarlo simulated some third-hand smoke exposure in the lab. First， they pumped cigarette smoke into a Pyrex1 container， allowing the smoke chemicals to be deposited inside. Then they pumped any residual smoke out of the container before pulling outdoor air through it to clear out any second-hand smoke.

為了探究這一驚人發(fā)現(xiàn)的背后原因，埃弗里和德卡洛在實驗室中模擬了若干種接觸到三手煙的場景。首先，他們將煙草煙霧泵入一個派熱克斯耐熱玻璃容器，使煙霧中的化學物質(zhì)沉積其中。隨后，將容器中的所有殘留煙霧抽出，再注入室外空氣，以徹底清除殘留的二手煙霧。

After a day， filtered outdoor air was circulated through the container and the researchers measured the chemical composition of the aerosol particles it acquired along the way and compared it to outdoor air that hadn’t passed through the container. They found a 13 percent increase in third-hand smoke chemical species in the air that went through the Pyrex container， which meant that， though it seemed as though the smoke had cleared， a chemical residue still existed—and found a way to attach to passing aerosol particles.

一天后，研究人員將過濾后的室外空氣在容器中循環(huán)，檢測此過程之后氣溶膠顆粒的化學成分，并與未流經(jīng)容器的室外空氣進行比較分析。他們發(fā)現(xiàn)，流經(jīng)玻璃容器的空氣中三手煙化學物質(zhì)增加了13%，這意味著，玻璃容器中的煙霧看似已經(jīng)清除，實則仍有殘留的化學物質(zhì)，并且得以附著于從容器中通過的氣溶膠顆粒。

“This means that our discovery was by no means unique to that classroom， in fact， it’s likely quite a widespread phenomenon，” DeCarlo said. “What we’d actually uncovered was a new exposure route for third-hand smoke—through aerosol particles， which are ubiquitous in the indoor environment.”

“這說明我們的研究發(fā)現(xiàn)絕非局限于那間教室，事實上，這可能是一種相當普遍的現(xiàn)象?！钡驴宀┦空f，“我們實際上發(fā)現(xiàn)了一種接觸到三手煙的新途徑，即通過室內(nèi)環(huán)境中無處不在的氣溶膠顆粒進行傳播。”

Hitching a ride

搭便車

Previous research on third-hand smoke chemicals has shown that as they transition out of gas form， they can settle just about anywhere. They can attach to clothing and furniture， on skin or hair—even onto a sterile surface， such as the Pyrex container， as the Drexel researchers found. But they can concentrate in particles when the chemicals are in gas form and they are exposed to acidic， liquid aerosols.

前期研究表明，三手煙化學物質(zhì)脫離氣態(tài)以后，可以沉積于任何地方。它們可以附著在衣物、家具、皮膚或毛發(fā)上，甚至如德雷塞爾大學研究員發(fā)現(xiàn)的那樣，可以附著于像派熱克斯耐熱玻璃容器這樣的無菌表面。但當這些化學物質(zhì)處于氣態(tài)并接觸到酸性液態(tài)氣溶膠時，它們就可以在氣溶膠顆粒中聚集。

This means that they can be unwittingly transported into smoke-free envir-onments—lying in wait for conditions that allow them to transition back into a gas and attach to aerosols.

這意味著化學物質(zhì)可能在不知不覺中被傳播至無煙環(huán)境中，等待時機變回氣態(tài)附著于氣溶膠之上。

But as it turns out， this combination of conditions is actually pretty common indoors. The study suggests that third-hand smoke chemicals on indoor surfaces can “repartition，” or return， to the gas phase when they’re exposed to chemicals such as ammonia—which is common in buildings as it’s emitted when people breathe and often found in bathrooms.

實際上，在室內(nèi)環(huán)境中，上述條件很容易達成。該研究表明，附著于室內(nèi)物體表面的三手煙化學物質(zhì)接觸到氨等化學物質(zhì)時，會“重新分配”，即重返氣態(tài)。氨氣在建筑物內(nèi)很常見，人呼吸時會釋放氨氣，衛(wèi)生間也是氨氣聚集地。

And the aqueous aerosols they need for transportation？

那么三手煙化學物質(zhì)傳播所需的液相氣溶膠從何而來呢？

“In the summertime warm air with varying amounts of water content is brought into the building， mixed with recirculated air， and conditioned to cooler temperatures，” they write. “This process leads to significant uptake of water by aerosol particles. This continuous summertime presence of aerosol water allows third-hand smoke chemicals to partition2 into the aerosol phase.”

“夏季，水分含量不一的暖空氣進入建筑物內(nèi)部，與再循環(huán)空氣混合并降溫?！毖芯咳藛T寫道，“在這一過程中，氣溶膠顆粒大量吸收水分。正是由于夏季持續(xù)存在氣溶膠水，三手煙化學物質(zhì)得以分離出來進入氣溶膠顆粒?！?/p>

Indeed， the indoor environment of buildings with mechanical heating， ventilation and air conditioning （HVAC） can be the precise confluence of factors necessary to spread these toxic chemicals.

事實上，配備暖通空調(diào)系統(tǒng)（用于供暖、通風和空氣調(diào)節(jié)）的室內(nèi)環(huán)境，正好可以匯集傳播這些有毒物質(zhì)所需的各種條件。

“The HVAC system not only serves to condition the aerosols to wet or dry states， but also to move air through a building zone. HVAC systems recirculate and disperse air throughout the multiple rooms of the zone served by the system，” they write. “For this reason， a room located near a smoking area with smoke penetration or a room occupied by a smoker can effectively expose the other occupants served by the same HVAC system to third-hand smoke， even if they do not share space directly.”

研究人員寫道：“暖通空調(diào)系統(tǒng)不僅調(diào)控著氣溶膠的干濕狀態(tài)，還能促使室內(nèi)外空氣流動。空氣可以在使用該系統(tǒng)的眾多房間之間再循環(huán)和擴散。因此，即便大家并未直接共享同一空間，建筑物內(nèi)的不吸煙者也難逃三手煙影響，就因他們所待房間與臨近吸煙區(qū)并有煙霧滲透的房間或吸煙者的房間共用暖通空調(diào)系統(tǒng)。”

Breathing easy？

易于吸入？

The researchers note that the persistence of the chemicals in the indoor environment is also linked to the amount of surface area in a particular room or building. This is because the third-hand smoke that isn’t inhaled can deposit just about anywhere—counters， wallcuuck2+pfbCXk3jcD8UTNA==s， furniture even embedding in carpet—and later return to the air when conditions are right.

研究人員指出，化學物質(zhì)在室內(nèi)環(huán)境中的滯留還與特定房間或建筑內(nèi)的表面積大小密切相關。這是因為未被人吸入的三手煙幾乎無孔不入，可以黏附在任何地方，比如柜臺、墻壁、家具，甚至嵌入地毯，待條件適宜時再次釋放到空氣中。

“While most people expect that they’ll be exposed to car exhaust， or other chemicals in low concentrations when they’re outside—they tend to think that they’re escaping all that when they step indoors，” DeCarlo said. “Understanding that we are constantly exposed to these chemicals， even in our workplaces， is a challenge to communicate to the general population.”

德卡洛說道：“大多數(shù)人能預料在室外會接觸到汽車尾氣或其他低濃度化學物質(zhì)，傾向于相信只要進入室內(nèi)就能避開它們。但現(xiàn)實情況是，即便是在室內(nèi)工作場所中，我們也會不斷接觸到各類化學物質(zhì)。讓公眾了解這一事實是一項挑戰(zhàn)?！?/p>

（譯者單位：中央民族大學外國語學院）

1 Pyrex派熱克斯玻璃是抗熱性能極佳的一種玻璃，被廣泛應用于廚房用品、化學實驗室儀器及光學設備等，它已成為其原材料硼化玻璃的通用性商標。

2 partition分隔，隔開。