Ozonation is a common remediation approach to eliminate odors from mold, tobacco and fire damage in buildings. Little information exists to: 1) assess its effectiveness; 2) provide guidance on operation conditions; and 3) identify potential risks associated with the presence of indoor ozone and ozonation byproducts. The goal of this study is to evaluate chemical changes in thirdhand smoke (THS) aerosols induced by high levels of ozone, in comparison with THS aerosols aged under similar conditions in the absence of ozone. Samples representing different stages of smoke aging in the absence of ozone, including freshly emitted secondhand smoke (SHS) and THS, were collected inside an 18-m³ room-sized chamber over a period of 42 hours after six cigarettes were consumed. The experiments involved collection and analysis of gas phase species including volatile organic compounds (VOCs), volatile carbonyls, semivolatile organic compounds (SVOCs), and particulate matter. VOC analysis was carried out by gas chromatography/mass spectrometry with a thermal desorption inlet (TD-GC/MS), and volatile carbonyls were analyzed by on-line derivatization with dinitrophenylhydrazine (DNPH), followed by liquid chromatography with UV/VIS detection. SVOCs were extracted from XAD-coated denuders and Teflon-coated fiberglass filters in the absence of ozone. In those extracts, tobacco-specific nitrosamines (TSNAs) and other SVOCs were analyzed by gas chromatography with positive chemical ionization-triple quadrupole mass spectrometric detection (GC/PCI-QQQ-MS), and polycyclic aromatic hydrocarbons (PAHs) were quantified by gas chromatography with ion trap mass spectrometric detection (GC/IT-MS) in selected ion monitoring mode. Particulate matter concentration was determined gravimetrically. In a second experiment, a 300 mg h^-1 commercial ozone generator was operated during one hour, one day after smoke was generated, to evaluate the remediation of THS by ozonation. VOCs and volatile carbonyls were analyzed before and after ozonation. Extracts from fabrics that were exposed in the chamber before and after ozonation as surrogates for indoor furnishings were analyzed by GC/IT-MS, and aerosol size distribution was studied with a real-time scanning mobility particle sizer. Ozone concentration was measured with a photometric detector. An estimated 175 mg ozone reacted with THS after one hour of treatment, corresponding to 58% of the total O₃ released during that period. Fabric-bound nicotine was depleted after ozonation, and the surface concentration of PAHs adsorbed to fabric specimens decreased by an order of magnitude due to reaction with ozone, reaching pre-smoking levels. These results suggest that ozonation has the potential to remove harmful THS chemicals from indoor surfaces. However, gas phase concentrations of volatile carbonyls, including formaldehyde, acetaldehyde and acetone were higher immediately after ozonation. Ultrafine particles (UFP, in most cases with size <60 nm) were a major ozonation byproduct. UFP number concentrations peaked shortly after ozonation ended, and remained at higher-than background levels for several hours. Based on these results, minimum re-entry times after ozone treatment were predicted for different indoor scenarios. Clearly defining re-entry times can serve as a practical measure to prevent acute human exposure to ozone and harmful ozonation byproducts after treatment. This study evaluated potential benefits and risks associated with THS remediation using ozone, providing insights into this technology.

臭氧处理是一种常见的补救方法，可消除建筑物中发霉，发烟和起火造成的气味。几乎没有信息可用于：1）评估其有效性；2）提供操作条件指导；3）确定与室内臭氧和臭氧化副产物的存在有关的潜在风险。这项研究的目的是，与在没有臭氧的情况下在类似条件下老化的THS气溶胶相比，评估由高水平的臭氧引起的二手烟（THS）气溶胶的化学变化。在18 m ^3的空间内收集了代表没有臭氧的烟雾老化不同阶段的样本，包括新鲜散发的二手烟（SHS）和THS。消耗了六支香烟后，在42小时内达到了房间大小的房间。实验涉及气相种类的收集和分析，其中包括挥发性有机化合物（VOC），挥发性羰基，半挥发性有机化合物（SVOC）和颗粒物。通过气相色谱/质谱联用热脱附入口（TD-GC / MS）进行VOC分析，并通过使用二硝基苯肼（DNPH）在线衍生化分析挥发性羰基，然后通过具有UV / VIS检测的液相色谱进行分析。SVOC是在没有臭氧的情况下从XAD涂层的剥蚀仪和Teflon涂层的玻璃纤维过滤器中提取的。在这些摘录中 采用正化学电离三重四极杆质谱（GC / PCI-QQQ-MS）进行气相色谱分析，分析烟草特有的亚硝胺（TSNA）和其他SVOC，并通过带离子阱的气相色谱法对多环芳烃（PAH）进行定量所选离子监测模式下的质谱检测（GC / IT-MS）。重量法测定颗粒物浓度。在第二个实验中，^-1商用臭氧发生器在产生烟气的一天后的1小时内运行，以评估臭氧处理对THS的修复。在臭氧化之前和之后分析VOC和挥发性羰基。通过GC / IT-MS分析了臭氧处理前后暴露在室内的织物提取物作为室内装饰的替代物，并使用实时扫描迁移率粒度仪研究了气溶胶粒径分布。用光度检测器测量臭氧浓度。处理一小时后，估计有175 mg臭氧与THS反应，相当于O ₃总量的58％在此期间释放。臭氧处理后，与织物结合的尼古丁消耗ple尽，由于与臭氧的反应，吸附在织物样品上的PAHs的表面浓度降低了一个数量级，达到了吸烟前的水平。这些结果表明，臭氧化有可能从室内表面去除有害的THS化学物质。但是，臭氧化后，挥发性羰基化合物（包括甲醛，乙醛和丙酮）的气相浓度立即升高。超细颗粒（UFP，大多数情况下尺寸小于60 nm）是主要的臭氧化副产物。臭氧化作用结束后不久，UFP数浓度达到峰值，并保持高于背景水平数小时。根据这些结果，可以预测不同室内情况下臭氧处理后的最小再进入时间。明确规定再入时间可以作为一种实用措施，以防止人类急性接触治疗后的臭氧和有害的臭氧化副产物。这项研究评估了与使用臭氧进行THS修复相关的潜在收益和风险，从而提供了对该技术的见解。