背景:自COVID-19大流行以来,建筑物通风对保护健康的重要性已得到更广泛的认可。建筑物中的室外空气通风稀释了室内产生的空气污染物(包括生物气溶胶),并减少了由此产生的居住者暴露。许多国家和组织都有关于最低通风率(VR)的咨询指南或强制性标准,以保持室内空气质量(IAQ)。因为直接测量VRs通常很困难,许多IAQ指南反而规定了二氧化碳(CO2)的室内浓度限值,使用建筑物居住者呼出的二氧化碳作为VR的指标。虽然室内二氧化碳准则很常见,各种二氧化碳限制的证据基础尚不清楚。
目的:回顾当前全球室内二氧化碳排放指南和提供的支持性证据。
方法:我们确定了全球基于CO2的IAQ或通风指南,以及提供的任何支持性证据。我们排除了二氧化碳含量≥5000ppm的职业指南。
结果:在确定的43个指南中,35设置单个CO2浓度限值和八个设置多层限值;16没有提到要控制的特定人类影响,19只指定气味不满意,五种特定的非传染性健康影响,和三种特定的空气传播传染病。最常见的室内CO2限制为1000ppm。13条准则规定了最大二氧化碳限制为延长的时间加权平均值,没有证据表明平均极限与乘员效应有关。只有18个指南引用了支持限制的证据,我们发现这个证据有说服力。在这八项准则中,七个设置限制以控制气味感知。一个提供了17个基于科学的二氧化碳限制,对于特定的空间使用和占用示例,控制COVID-19在室内的远程传播。
结论:目前许多室内二氧化碳(CO2)关于室内空气质量的指南都没有规定要控制的不利影响。气味不满意是最常见的影响,很少有人提到健康,和三个提到的传染病控制。只有一个二氧化碳指南是从科学模型中开发出来的,以控制COVID-19的空中传播。大多数指南没有为指定的限制提供支持性证据;很少提供有说服力的证据。没有科学依据可以为所有建筑物的IAQ设定一个CO2限值,将IAQ的CO2限制设置为扩展的时间加权平均值,或使用一次性CO2测量来验证所需的VR。
BACKGROUND: The importance of building ventilation to protect health has been more widely recognized since the COVID-19 pandemic. Outdoor air ventilation in buildings dilutes indoor-generated air pollutants (including bioaerosols) and reduces resulting occupant exposures. Many countries and organizations have advisory
guidelines or mandatory standards for minimum ventilation rates (VRs) to maintain indoor air quality (IAQ). Because directly measuring VRs is often difficult, many IAQ guidelines instead specify indoor concentration limits for carbon dioxide (CO2), using CO2 exhaled by building occupants as an indicator of VR. Although indoor CO2
guidelines are common, the evidence basis for the various CO2 limits has not been clear.
OBJECTIVE: To review current indoor CO2 guidelines worldwide and the supportive evidence provided.
METHODS: We identified worldwide CO2-based guidelines for IAQ or ventilation, along with any supportive evidence provided. We excluded occupational
guidelines for CO2 levels ≥5000 ppm.
RESULTS: Among 43 guidelines identified, 35 set single CO2 concentration limits and eight set multi-tiered limits; 16 mentioned no specific human effect to be controlled, 19 specified only odor dissatisfaction, five specified non-infectious health effects, and three specified airborne infectious disease transmission. The most common indoor CO2 limit was 1000 ppm. Thirteen guidelines specified maximum CO2 limits as extended time-weighted averages, none with evidence linking averaged limits to occupant effects. Of only 18 guidelines citing evidence to support limits set, we found this evidence persuasive for eight. Among these eight
guidelines, seven set limits to control odor perception. One provided 17 scientifically-based CO2 limits, for specific example space uses and occupancies, to control long-range COVID-19 transmission indoors.
CONCLUSIONS: Many current indoor carbon dioxide (CO2) guidelines for indoor air quality specified no adverse effects intended for control. Odor dissatisfaction was the effect mentioned most frequently, few mentioned health, and three mentioned control of infectious disease. Only one CO2
guideline was developed from scientific models to control airborne transmission of COVID-19. Most guidelines provided no supportive evidence for specified limits; few provided persuasive evidence. No scientific basis is apparent for setting one CO2 limit for IAQ across all buildings, setting a CO2 limit for IAQ as an extended time-weighted average, or using any arbitrary one-time CO2 measurement to verify a desired VR.