Air Quality Research Center, University of California at Davis , Davis , California , USA.
Albany High School , Albany , California , USA.
J Air Waste Manag Assoc. 2019 Sep;69(9):1015-1022. doi: 10.1080/10962247.2019.1629362. Epub 2019 Jul 17.
A low-cost air sensor package was used to monitor indoor air quality (IAQ) in a classroom at the Albany Middle School in the San Francisco Bay Area of California. A rapid increase in carbon dioxide (CO) was observed in the classroom as soon as it is occupied. When the classroom is unoccupied, the CO levels decay slowly toward the outdoor background level. All high CO concentrations observed inside the classroom, above the outdoor background, was due to exhaling of the occupants. The CO concentrations generally exceed the recommended level of 1000 ppb towards the end of the school day. The exceedances and slow decay may suggest that the ventilation rate in this school is not sufficient. The particulate level in the classroom was low until a distant wildfire advected large amount of particulate matter to the San Francisco Bay Area. Very high (10-15 times compared to the background) particle numbers (per m of particles with diameter >0.3 µm) were observed in the classroom during the wildfire. These particles were relatively small (0.3-1.0 µm) and the filters (MERV 8) of the ventilation system were unable to filter them out. Therefore, the measurements made by low-cost particle counters can inform the school administrators of adverse IAQ during future wildfire (or other combustion) events. The particle number was independent of the occupation before and during the wildfire suggesting that all observed particles were infiltrated into the classroom from outside. Consistent with previous studies, no appreciable increase in the local ambient CO background was observed during this distant wildfire event. : Low-cost air sensors are effective in monitoring indoor air quality in classrooms. The CO levels in classrooms are mainly generated indoors due to exhalation of occupants. Concentration of CO generally exceed the recommended level of 1000 ppb towards the end of the school day. In contrast, the particulate matter mostly comes from outdoors and small particles penetrate though the filters normally used at schools. Distant wildfires do not increase the local CO background appreciably, but significantly increase the particulate matter concentrations both indoors and outdoors. Further investigations are needed to assure that ventilation rates in classrooms are sufficiently health protective.
一个低成本的空气传感器套件被用于监测加利福尼亚州旧金山湾区奥尔巴尼中学的一间教室的室内空气质量 (IAQ)。一旦教室被占用，二氧化碳 (CO) 就会迅速增加。当教室无人时，CO 浓度会缓慢衰减到室外背景水平。教室内所有高于室外背景的高 CO 浓度都是由于学生的呼气造成的。在学校的最后阶段，CO 浓度通常会超过 1000ppb 的推荐水平。CO 浓度的超标和缓慢衰减可能表明该校的通风率不足。在教室的颗粒物水平很低，直到远处的野火将大量颗粒物输送到旧金山湾区。在野火期间，教室中观察到非常高的颗粒物数量（每立方米大于 0.3µm 的颗粒物数量）（与背景相比高出 10-15 倍）。这些颗粒相对较小（0.3-1.0µm），通风系统的过滤器（MERV 8）无法将其过滤掉。因此，低成本粒子计数器的测量结果可以在未来野火（或其他燃烧）事件期间告知学校管理人员不利的室内空气质量。在野火前后，粒子数量与人员占用无关，这表明所有观察到的粒子都是从外部渗透到教室中的。与之前的研究一致，在这次远距离野火事件中，没有观察到当地环境 CO 背景的明显增加。低成本空气传感器在监测教室室内空气质量方面非常有效。教室中的 CO 水平主要是由于学生的呼气而在室内产生的。CO 浓度通常在学校日结束时超过 1000ppb 的推荐水平。相比之下，颗粒物主要来自室外，小颗粒会穿透学校通常使用的过滤器。远距离野火不会明显增加当地 CO 背景，但会显著增加室内外颗粒物浓度。需要进一步调查以确保教室的通风率足以保护健康。
