Indoor air最新文献

Indoor air quality is becoming one of the most important factors for public health, as people tend to spend more time indoors, either at home or at work. This paper combines the use of calibrated low-cost particulate matter (PM) sensors with source apportionment algorithms to understand the factors that affect the indoor air quality within a typical UK school. Low-cost optical particle counter (OPC) sensors were placed in three different classrooms within the school, measuring PM concentrations during a typical school week and the subsequent holiday period, to understand the role of occupancy within schools for air quality. When students were in attendance during school hours (09:00–15:30), the classroom with the greatest average PM levels had PM_2.5 and PM₁₀ mass concentrations of 14.4 and 51.0 μg/m³, respectively. During school hours, when students were present, all classrooms had average PM_2.5 concentrations greater than 8.1 μg m⁻³ and average PM₁₀ concentrations greater than 13.1 μg m⁻³. Notably, the English studies classroom exceeded the 24-h WHO ambient PM₁₀ guideline (45 μg m⁻³). Employing the non-negative matrix factorization (NMF) algorithm for source apportionment revealed that between 93% and 98% of PM₁ observed within classrooms derived from outdoor sources. This contribution diminished as particle size increased, with outdoor sources accounting for 74%–89% of PM_2.5, and 19%–40% of PM₁₀, respectively. The differences in classroom PM concentration and source percentages are attributed to differences in lesson activities, lesson frequency, flooring (carpeted versus hard flooring), location within the school, and proximity to outdoor sources such as roads. The approach described within the paper is easily translated to other indoor locations and could also be straightforwardly scaled due to its relatively low cost. Thereby, it allows for air quality management in locations crucial for the public health and educational outcomes of children.

Understanding radon-prone areas is vital to prevent radon-related health problems, enhance public safety, and ensure adherence to regulations aimed at minimizing radon exposure. We conducted a comprehensive review of cross-sectional studies reporting on residential radon exposure in Iran. Our review encompassed studies published until February 13, 2022. Out of the 966 articles initially identified, 37 studies were included in our analysis, which measured indoor radon levels in a total of 3480 residential buildings in Iran. Notably, the highest residential radon levels (Bq.m⁻³) were found in Mazandaran province, with the most hazardous recorded levels in Talesh Mahalleh (3235), followed by Ramsar (1299). Conversely, Tehran, the capital city of Iran, had the lowest recorded levels of residential radon, at 11.0 Bq.m⁻³. Remarkably, indoor radon concentration exceeded both the reference levels recommended by the World Health Organization (WHO) and the standard levels set by the U.S. Environmental Protection Agency (US.EPA), with approximately 51% and 26%, respectively. The mean effective doses received by Iranian residents were 5.0 mSv.y⁻¹ (0.3–81.7). Moreover, the mean excess lifetime cancer risk (ELCR) associated with indoor radon exposure was determined to be two per 1000 people. The annual incidence of lung cancer cases (LCCs) per million people attributed to indoor radon exposure in Iranian residential buildings ranged from 5.00E − 06 to 1.47E − 03. The included studies addressed a wide range of variables affecting radon levels, but they did not cover all factors comprehensively. These factors encompass the meteorological parameters, geological characteristics, building construction materials, building type, window type, occupancy information, and ventilation rates in enclosed spaces. The potential health risks associated with indoor radon exposure necessitate the implementation of effective control measures. These should include raising public awareness, revising construction regulations, enhancing ventilation systems, identifying high-risk areas, and conducting more comprehensive studies to better understand the factors that influence radon concentration.

The cytotoxicity of PM_2.5 (fine particulate) derived from varying fuels burning in different microenvironments remains unclear. In this study, the toxicity of PM_2.5 collected from northern China in the winter on human cervical carcinoma (HeLa) cells was determined. The PM_2.5 from chunk coal (CC) combustion caused greater apoptosis (22.47%) than firewood (FW) burning (5.32%), while the effects on cell viability showed contrary patterns between FW (stimulation: 132.38%) and CC (inhibition: 87.05%). Furthermore, all the samples induced significant oxidative stress and inflammatory responses in cells. Intriguingly, PM_2.5 samples collected from FW burning upregulated the expression genes involved in pathways in cancer, whereas those from CC burning downregulated the levels. Accordingly, the health risks of different samples were assessed through a probabilistic model. The risk level of samples of CC burning from the living room (CC/L) was 0.752, followed by CC from the bedroom (CC/B, 0.736), and then CC from the kitchen (CC/K, 0.562), FW without a chimney (FW-C, 0.451), and FW with a chimney (FW+C, 0.446). Meanwhile, the survival curves established by gene expression indicated that PM_2.5 from FW might be positively correlated with cancer progression. This pilot investigation demonstrated that CC combustion in the living room posed the highest health risk, and improved cookstoves (with a chimney) markedly reduced the risk. This pilot study presents a novel model for assessing health risks associated with air pollution using the toxicology method and real-time PM_2.5 quantification.

People generally spend most of their time indoors; thus, household air pollution (HAP), especially indoor air pollution, is of paramount importance. In this study, real-time particulate matter (PM_2.5) monitors were used to collect high temporal resolution concentrations of fine PM_2.5 in different microenvironments from 104 urban and rural households in Guizhou Province to investigate the urban–rural difference in HAP and the contribution of cooking activity to HAP. Results showed that PM_2.5 concentrations among different rural microenvironments varied largely, ranging from 26.10 ± 33.27 (mean ± standard deviation) in the bedroom to 69.20 ± 72.50 μg/m³ in the kitchen while varying slightly across various urban microenvironments, ranging from 32.30 ± 17.5 in the living room to 34.65 ± 16.37 μg/m³ in the kitchen. Cooking activity can rapidly increase PM_2.5 concentrations in the kitchen, whose peaks were at least five times higher than baseline levels. The contribution of cooking to the kitchen PM_2.5 was 18.43 ± 12.17% and 5.39 ± 4.15% in rural and urban homes, respectively. Biomass burning affected indoor PM_2.5 concentrations significantly, where rural households using biomass had the highest PM_2.5 levels than households burning other fuels. This study identified the urban–rural disparities in household PM_2.5 pollution and the contributions of cooking activities to HAP, illustrating the importance of cooking activities to indoor air pollution, which can assist in controlling indoor air pollution.

Background: Volatile organic compounds (VOCs) are indoor and outdoor air pollution, but the VOCs that were shared across chronic respiratory diseases (CRDs) remained unknown. Meanwhile, the mediating roles of system inflammation need to be further explored.

Methods: This study included 9114 adults based on the National Health and Nutrition Examination Survey (NHANES) 2005–2006 and 2011–2018. Internal exposure levels of 14 urinary metabolites of VOC (mVOCs), blood cell count–derived inflammatory biomarkers, and prevalent CRDs, including asthma, chronic bronchitis, and emphysema, were assessed and collected. Associations of single- and multiple-mVOCs with CRDs were assessed by using logistic regression and quantile-based g-computation (QGcomp) methods to select the key and shared mVOCs among CRDs. Mediation effects of system inflammation on mVOC-CRD associations were further evaluated by causal mediation analysis.

Results: Increased levels of total 14 mVOCs were associated with increased risk of chronic bronchitis (OR = 1.62, 95% CI: 1.37–1.91), emphysema (OR = 1.73, 95% CI: 1.27–2.35), and both conditions combined (defined as chronic obstructive pulmonary disease, COPD) (OR = 1.61, 95% CI: 1.37–1.88), but not for asthma (OR = 1.07, 95% CI: 0.94–1.21). In both single- and multiple-mVOC exposure models, 8 key mVOCs were COPD associated, including 6 mVOCs (34MHA, AMCC, CEMA, DHBMA, 3HPMA, and MHBMA3) and 5 mVOCs (34MHA, CYMA, 3HPMA, MA, and MHBMA3) that were associated with increased risk of chronic bronchitis and emphysema, respectively. Particularly, 34MHA, 3HPMA, and MHBMA3 were shared risk factors across chronic bronchitis, emphysema, and COPD. Neutrophils mediated the associations of three shared mVOCs with chronic bronchitis (by 5.20%, 7.80%, 6.30%), emphysema (by 6.90%, 9.30%, 9.70%), and COPD (by 5.80%, 8.90%, 7.70%).

Conclusions: These findings provide valuable insights into the shared risk mVOCs and mediating roles of neutrophils involved in the pathogenesis of CRDs, which can be useful in developing more effective prevention and intervention strategies for CRDs.

In regions experiencing severe cold, inadequate ventilation during winter months often leads to increased concentrations of indoor pollutants. While there have been several studies on indoor particulate matter and inorganic pollutants in such regions, bioaerosol pollution has not been as extensively investigated. This study examines the indoor bioaerosol situation in a university located in one of the severe cold regions in China, focusing on bacteria as a representative pollutant. It investigated random samples of an office and a dormitory (including washrooms) and spanned heating and nonheating periods. The findings indicated that bacterial abundance in the dormitory and office was approximately equivalent. The predominant airborne bacterial communities identified were Proteobacteria, Bacteroidota, Actinobacteriota, Firmicutes, and Myxococcota. Opening windows effectively reduced bacterial concentrations during both heating and nonheating periods. When windows remained closed, bacterial concentrations exceeded the standard by 9.1% during the nonheating period and by 14.3% during the heating period. Furthermore, temperature and relative humidity influenced bacterial particle size, activity, and consequently, aerosol concentrations. In the office, the highest percentage of bioaerosols was observed in particle sizes <1.1 and 1.1–2.1 μm, with smaller percentages observed in other particle sizes. Conversely, the percentage of particle sizes 2.1–3.3 μm in the dormitory was higher. The highest bacterial aerosol concentrations were detected in the morning in both the dormitory and office, during heating and nonheating periods. Bacterial concentrations in the office were lower on weekends than on weekdays, whereas in the dormitory, concentrations were higher on weekends than on weekdays. The above results indicate that indoor bacterial aerosol pollution is serious in winter in severe cold regions, which needs more attention.

In the quest to optimize residential environments for health and sustainability, understanding the interaction between pedestrian dynamics and environmental parameters is crucial. This study delves into this intersection by conducting a detailed spatial-temporal analysis within an apartment building. The research reveals pivotal insights about the relationship between pedestrian flow and environmental quality. Key findings reveal distinct patterns in pedestrian traffic, with two main peaks in early morning and late evening, accounting for approximately 24% of daily movement. The study identifies a pronounced preference for upward elevator use, reflecting residents’ lifestyle and floor-level choices. Importantly, we observed variable correlations between pedestrian flow and environmental pollutants. Pollutants like PM_2.5 and carbon monoxide exhibited weak correlations, while noise, TVOC, formaldehyde, and ozone showed stronger associations with human movement. The research uncovered significant spatial differences in pollutant levels across the building, with higher particulate matter and ozone levels in the seventh-floor elevator room. The data suggest a need for tailored pollution management strategies, especially for noise and hazardous compounds like formaldehyde and ozone, which exceed safety limits in certain areas. Our findings offer critical insights for the design and management of residential environments, emphasizing the importance of considering both pedestrian flow and environmental factors in optimizing living spaces for health and efficiency.

Radon is a source of ionizing radiation that shows a carcinogenic potential. Thus, tracking radon exposure levels in the environment and managing exposure conditions is necessary for reducing the hazards such as lung cancer, which is known to be the second largest impact of radon on humans worldwide. A LR-115 Type II strippable detector for monitoring radon radiation was installed in 30 mud and 26 block houses in the periurban (Duakor) areas in the Cape Coast Metropolis, Central Region, for 3 months to determine the exposure levels. The results showed that block houses (n = 26) had a radon ionization concentration in a range of 125–356 Bq m⁻³ and mean of 221 ± 61.4 Bq m⁻³, which was significantly higher than that of mud houses (n = 30), which ranged from 50.8 to 349 Bq m⁻³, with a mean of 186 ± 13.3 Bq m⁻³. About 80% and 10% of both types of houses showed levels that were above WHO’s lower (100 Bq m⁻³) and upper (300 Bq m⁻³) limits of the annual residential guidelines. Moreover, over 70% of both building types showed annual effective doses of indoor radon levels that were within the action levels (3–10 mSv year⁻¹). The data shows that the occupants have lived in their apartments for more than 10 years, while only about 3.0% have ever received some education on radon. Additional steps to manage indoor radon exposure in the community to avoid lung cancer are necessary.

Surface dust in urban environments is an important carrier and potential source of polycyclic aromatic hydrocarbons (PAHs). However, information regarding PAHs in underground parking garage (UPG) surface dust is still limited. In the present study, a total of 30 surface dust samples were collected from UPGs in apartment communities to assess the content, potential health risks to residents and sources of PAHs. The results showed that the total PAH content in the surface dust in the UPGs ranged from 636.27 to 25448.62 μg/kg, with a mean content of 4097.73 μg/kg. The distribution pattern of PAHs based on ring number exhibited the following order: 2–3 > 5–6 > 4 rings. All these surface dust samples were contaminated with PAHs, and 80% were heavily contaminated (ΣPAH > 1000 μg/kg). Health risk assessment revealed that the mean total carcinogenic risk (TCR) for children and adults was 1.33 × 10⁻⁶ and 1.01 × 10⁻⁶, respectively, indicating that residents suffered acceptable carcinogenic risk. The diagnostic ratios and positive matrix factorization results indicate that pyrogenesis was the primary source of PAHs in UPG surface dust, with diesel combustion, gasoline combustion, vehicular emission, and coal combustion contributing 8.2%, 42.8%, 27.9%, and 21.1%, respectively. These results indicate that effective measures should be implemented to protect local workers and residents from carcinogenic effects.

Proper design and operation of buildings are expected to result in optimal thermal comfort and energy performance at the same time. If occupants are not satisfied with thermal conditions, corrective actions by building managers and maintenance staff may lead to elevated room temperatures with evident energy penalties. Because of complicated technical systems and control logic, it is worth studying how well the design intent has been realised in new office buildings. In this study, thermal comfort was analysed by measurements of draught, room, and supply air temperature as well as with occupant questionnaire surveys in five modern office buildings. Both short- and long-term measurements were conducted to demonstrate problems in the operation and to find potential solutions for improvement. The results revealed an issue of excessive overheating during the heating season despite generally low air velocities. Radiant ceiling panels had the lowest velocities in both summer and winter, while buildings with active chilled beams showed the potential to meet Category II air velocity and temperature requirements. The building with thermally activated building systems experienced the most overheating during the heating season. Occupants were satisfied with the heating season temperatures of 23°C–25°C that can be attributed to lighter clothing (0.7 clo) instead of the standard 1.0 clo. Ventilation supply air and indoor temperature analyses indicate that elevated setpoints have been used to compensate for draught, resulting in overheating. As a measure of improvement to avoid overheating, we propose control curves for room temperature based on the outdoor running mean temperature and for supply air temperature based on the extract air temperature.