Indoor Air

A large amount of surgical smoke in electrosurgery seriously deteriorates the clean environment of the operating room and can potentially harm medical staff and patients. Exploring the distribution and removal of indoor particulate matter and selecting efficient ventilation patterns are effective ways to control harmful smoke. Therefore, in this study, we combined simulations and full-scale experiments to quantitatively explore the high-concentration spatial regions of particles and compared three ventilation patterns: vertical laminar airflow (VLAF), horizontal laminar airflow (HLAF), and hybrid ventilation, wherein unidirectional airflow (UDAF) was applied to the operating table along with peripheral mixing (UDAF + mixing). We found that simple laminar flow ventilation was significantly affected by the equipment layout and air change rate (air changes per hour; ACH), and the smoke particles were distributed in large amounts in the operating area and could not be removed completely. Conversely, hybrid ventilation can work effectively, and the optimal ACH is approximately 60, which can remove nearly 72% of smoke particles. The airflow distribution in the operating room is also an important factor affecting the distribution and removal of smoke particles. Therefore, medical staff should avoid prolonged exposure to areas with high particle concentrations and particle removal paths.

Indoor air quality on board a 36-year-old ship has been characterized at several locations. The ship is dedicated to nearshore operations at the Belgian coast. This paper presents time-averaged and continuous-time measurements of several indoor pollutant concentrations such as NO₂, O₃, NO, CO, total volatile organic compounds (TVOC), polycyclic aromatic hydrocarbons (PAH), particulate matter PM_2.5 and PM₁₀, black carbon, and individual organic compounds. Time-averaged measurements suggest that the ship’s indoor air quality is sufficiently safe according to the prescribed occupational and nonoccupational health limits. However, the concentration of some indoor pollutants is comparable to that of the outdoor air of a large city such as Brussels, Belgium. Continuous-time analyses show that the temporal trends of indoor pollutant concentrations are inherently unstable. A large number of peaks or valleys are observed on a slowly fluctuating background. At some occasions, pollutant concentrations exceed the nonoccupational thresholds. Several pollutant peaks occur simultaneously, resulting in a pattern of peaks that is typical for a pollution source (e.g., exhaust gases entering the ship’s castle through the ventilation inlet, human presence, and bunkering). This study illustrates that multiparameter monitoring campaigns give valuable information about the behaviour of pollution sources, facilitating the definition of mitigation actions.

Residents and workers exposure to high carbon dioxide (CO₂) levels in buildings may cause headache, dyspnea, fatigue, or drowsiness. However, the effect of plants on in-building CO₂ reduction and adverse effect relief is largely unknown. We recruited 36 healthy participants from an office room with plants and 32 healthy participants from another office room without plant in the same office building in Taipei. The participants in the office room with plants during 2020 would move to the office room without plant in 2021. The twelve repeated measurements per year of CO₂, fine particles (PM_2.5), total volatile organic compounds (TVOCs), blood pressure (BP), serum CO₂ (TCO₂), and four rating questions of headache, dyspnea, fatigue, and drowsiness were obtained for each participant. The statistical results showed that levels of drowsiness and systolic BP were significantly lower among participants in the office room with plants compared to those in the office room without plants by -test and paired -test. The associations between increased indoor CO₂ and increased serum CO₂ were observed in the office room with plants (1.32%) and without plant (4.52%) by mixed-effects models. Also, the associations between indoor CO₂ and drowsiness were observed in office rooms (with plants: 14.57%; without plant: 3.82%). The conclusion of the present study is that plants in office environment can reduce CO₂ levels and may lower CO₂-related health effects.

The direct ingestion of indoor dust particles at historical heritage sites is a primary exposure pathway for employees to heavy metals. Water-soluble ions (WSIs) and heavy metal levels, sources, bioaccessibility, and health risks associated with indoor dust in the Mogao Grottoes were analyzed using comprehensive methods to determine the differences in the concentrations and distribution characteristics of WSIs and heavy metals between statue dust and floor dust. The concentrations of WSIs and heavy metals and the magnetic values of and SIRM in indoor dust were higher than those in street dust and topsoil. The mean and SIRM of statue dust particles were and . Specifically, the concentration of Pb was , 15-fold higher than the background value, indicating the continual receipt of heavy metals with high magnetic minerals during dust deposition. WSIs mainly originate from the weathering of surrounding rocks and earthen plaster; Pb originates from the shedding of paint of murals and sculptures; and Zn, Cu, and magnetic minerals originate from traffic sources. The bioaccessibility of heavy metals is high in the gastrointestinal phases of indoor dust. Overall, the health risks posed by heavy metals in indoor dust were low, with moderate to high risks in individual caves. Ingestion presents the highest noncarcinogenic and carcinogenic risk to employees. These results provide essential knowledge on indoor dust characteristics in the Mogao Grottoes, facilitating strategies for dust pollution mitigation and employee health risk control.

Cognitive performance is essential to foster learning. High CO₂ concentrations are common in classrooms and can lead to reduced cognitive performance. Negative air ions (NAIs) can improve cognitive performance. This study explored the effects of indoor NAIs on the cognitive performance and health of college students exposed to a high pure CO₂ environment. Forty college students were exposed to four sets of conditions (NAIs+500 ppm CO₂, 500 ppm CO₂, NAIs+2500 ppm CO₂, and 2500 ppm CO₂). Participants’ cognitive performance, including reasoning, short-term memory, concentration, and verbal ability, was assessed under each condition using the Cambridge Brain Sciences tool. Acute health symptoms were investigated using a subjective questionnaire, and simultaneously, participants’ blood pressure, heart rate, and lung function were tested. Analysis of variance (ANOVA) in a repeated-measures design was used to analyze the effects of different conditions on cognitive performance and health symptoms. The results revealed that the different levels of CO₂ and NAIs had a significant effect on cognitive performance after one hour of exposure and had no significant effect after three hours of exposure. Compared with 500 ppm CO₂, 500 ppm CO₂+NAIs resulted in better reasoning skills, short-term memory, and verbal skills, and 2500 ppm CO₂ led to poorer reasoning skills. The addition of NAIs to 2500 ppm CO₂ improved reasoning skills, short-term memory, and verbal skills. The benefits of adding NAIs to high pure CO₂ condition on cognitive performance are more noticeable than those to low CO₂ condition. Moreover, adding NAIs can reduce nasal irritation or dryness, skin irritation or dryness, sleepiness symptoms, and heart rate elevation caused by pure CO₂. However, the benefits of NAIs on health symptoms and physiology were not observed under the 500 ppm CO₂ condition. Adding NAIs to a high pure CO₂ level is an effective means to improve the cognitive performance and health of college students.

The purpose of this study was to measure the number and concentration of airborne particulates occurring in a dental clinic while performing dental procedures, with and without the simultaneous use of air purifier systems and a central ventilation system. The initial background concentrations of airborne particulates recorded during dental procedures, i.e., grinding of natural teeth and metals, without the use of air purifier systems, and with closed windows, reduced by 68% for ΡΜ₁₀, 77% for ΡΜ_2.5, and 81% for ΡΜ₁ when the same procedures were carried out with the simultaneous use of air purifying systems. In addition, measurements taken during patient treatment showed that an operating central ventilation system contributes to the reduction of airborne particles by a significant 94% for ΡΜ₁₀, 94% for ΡΜ_2.5, and 88% for ΡΜ₁ compared to dental procedures performed without the simultaneous use of air purifiers. Air purifying systems were also observed to contribute to the further reduction of airborne particulates when dental procedures were performed in combination with an operating central ventilation system. The majority of particles captured had diameters of 0.25-0.30 μm, 0.5 μm, and 1.0-4.0 μm, while particles with diameters of >5.0 μm were the least commonly observed in all experiments. Finally, a statistically significant difference between concentrations of particulate matter was recorded during dental procedures carried out with and without the simultaneous operation of air purifiers and central ventilation system increasing the risk of SARS-CoV-2 virus contamination in dental clinics due to the aerosols emitted by the use of common dental instruments during standard treatments.