Climate and health benefits of a transition from gas to electric cooking.

Household electrification is thought to be an important part of a carbon-neutral future and could also have additional benefits to adopting households such as improved air quality. However, the effectiveness of specific electrification policies in reducing total emissions and boosting household livelihoods remains a crucial open question in both developed and developing countries. We investigated a transition of more than 750,000 households from gas to electric cookstoves-one of the most popular residential electrification strategies-in Ecuador following a program that promoted induction stoves and assessed its impacts on electricity consumption, greenhouse gas emissions, and health. We estimate that the program resulted in a 5% increase in total residential electricity consumption between 2015 and 2021. By offsetting a commensurate amount of cooking gas combustion, we find that the program likely reduced national greenhouse gas emissions, thanks in part to the country's electricity grid being 80% hydropower in later parts of the time period. Increased induction stove uptake was also associated with declines in all-cause and respiratory-related hospitalizations nationwide. These findings suggest that, when the electricity grid is largely powered by renewables, gas-to-induction cooking transitions represent a promising way of amplifying the health and climate cobenefits of net-carbon-zero policies.

Nonthermal plasma air disinfection for the inactivation of airborne microorganisms in an experimental chamber and indoor air.

AIMS: Airborne transmission of diseases presents a serious threat to human health, so effective air disinfection technology to eliminate microorganisms in indoor air is very important. This study evaluated the effectiveness of a non-thermal plasma (NTP) air disinfector in both laboratory experiments and real environments. METHODS AND RESULTS: An experimental chamber was artificially polluted with a bioaerosol containing bacteria or viruses. Additionally, classroom environments with and without people present were used in field tests. Airborne microbial and particle concentrations were quantified. A 3.0 log10 reduction in the initial load was achieved when a virus-containing aerosol was disinfected for 60 min and a bacteria-containing aerosol was disinfected for 90 min. In the field test, when no people were present in the room, NTP disinfection decreased the airborne microbial and particle concentrations (P < 0.05). When people were present in the room, their constant activity continuously contaminated the indoor air, but all airborne indicators decreased (P < 0.05) except for planktonic bacteria (P = 0.094). CONCLUSIONS: NTP effectively inactivated microorganisms and particles in indoor air.

Transforming pollution into solutions: A bibliometric analysis and sustainable strategies for reducing indoor microplastics while converting to value-added products.

Microplastics (MPs), as emerging indoor contaminants, have garnered attention due to their ubiquity and unresolved implications for human health. These tiny particles have permeated indoor air and water, leading to inevitable human exposure. Preliminary evidence suggests MP exposure could be linked to respiratory, gastrointestinal, and potentially other health issues, yet the full scope of their effects remains unclear. To map the overall landscape of this research field, a bibliometric analysis based on research articles retrieved from the Web of Science database was conducted. The study synthesizes the current state of knowledge and spotlights the innovative mitigation strategies proposed to curb indoor MP pollution. These strategies involve minimizing the MP emission from source, advancements in filtration technology, aimed at reducing the MP exposure. Furthermore, this research sheds light on cutting-edge methods for converting MP waste into value-added products. These innovative approaches not only promise to alleviate environmental burdens but also contribute to a more sustainable and circular economy by transforming waste into resources such as biofuels, construction materials, and batteries. Despite these strides, this study acknowledges the ongoing challenges, including the need for more efficient removal technologies and a deeper understanding of MPs' health impacts. Looking forward, the study underscores the necessity for further research to fill these knowledge gaps, particularly in the areas of long-term health outcomes and the development of standardized, reliable methodologies for MP detection and quantification in indoor settings. This comprehensive approach paves the way for future exploration and the development of robust solutions to the complex issue of microplastic pollution.

Indoor air quality improvement with filtration and UV-C on mitigation of particulate matter and airborne bacteria: Monitoring and modeling.

Indoor air, especially with suspended particulate matter (PM), can be a carrier of airborne infectious pathogens. Without sufficient ventilation, airborne infectious diseases can be transmitted from one person to another. Indoor air quality (IAQ) significantly impacts people's daily lives as people spend 90% of their time indoors. An industrial-grade air cleaner prototype (filtration + ultraviolet light) was previously upgraded to clean indoor air to improve IAQ on two metrics: particulate matter (PM) and viable airborne bacteria. Previous experiments were conducted to test its removal efficiency on PM and airborne bacteria between the inlet and treated air. However, the longer-term improvement on IAQ would be more informative. Therefore, this research focused on quantifying longer-term improvement in a testing environment (poultry facility) loaded with high and variable PM and airborne bacteria concentrations. A 25-day experiment was conducted to treat indoor air using an air cleaner prototype with intermittent ON and OFF days in which PM and viable airborne bacteria were measured to quantify the treatment effect. The results showed an average of 55% reduction of total suspended particulate (TSP) concentration between OFF days (110 µg/m3) and ON days (49 µg/m3). An average of 47% reduction of total airborne viable bacteria concentrations was achieved between OFF days (∼3200 CFU/m3) and ON days (∼2000 CFU/m3). A cross-validation (CV) model was established to predict PM concentrations with five input variables, including the status of the air cleaner, time (h), ambient temperature, indoor relative humidity, and day of the week to help simulate the air-cleaning effect of this prototype. The model can approximately predict the air quality trend, and future improvements may be made to improve its accuracy.

Low-cost interventions to improve ventilation in long-term care facilities.

Residents of long-term care facilities are particularly vulnerable to communicable diseases. Low-cost interventions to increase air exchange rates (AERs) may be useful in reducing the transmission of airborne communicable diseases between long-term care residents and staff. In this study, carbon dioxide gas was used as a tracer to evaluate the AER associated with the implementation of low-cost ventilation interventions. Under baseline conditions with the room's door closed, the mean AER was 0.67 ACH; while baseline conditions with the door open had a significantly higher mean AER of 3.87 ACH (p < 0.001). Subsequently opening a window with the door open increased mean AER by 1.49 ACH (p = 0.012) and adding a fan in the window further increased mean AER by 1.87 ACH (p < 0.001). Regression analyses indicated that the flow rate of air entering through the window, both passively and through the use of a fan, was significantly associated with an increase in AER (p < 0.001). These results indicate that low-cost interventions that pull outside air into resident rooms were effective in improving the air exchange rates in these facilities. While implementation of these interventions is dependent on facility rules and isolation requirements of residents with airborne communicable diseases, these interventions remain viable options for long-term care facilities to improve resident room ventilation without requiring costly ventilation system upgrades.

Evaluation of photocatalysis inactivation in indoor air purification of pathogenic microbes by using the different nanomaterials based on TiO2 nanomaterials.

The photocatalytic technology for indoor air disinfection has been broadly studied in the last decade. Selecting proper photocatalysts with high disinfection efficiency remains to be a challenge. By doping with the incorporation of metals, the bandgap can be narrowed while avoiding the recombination of photogenerated charge. Three photocatalysts (Ag-TiO2, MnO2-TiO2, and MnS2-TiO2) were tested in photocatalytic sterilization process. The results revealed that Ag-TiO2 had the best antibacterial performance. Within 20 min, the concentration of Serratia marcescens (the tested bacteria) decreased log number of ln 4.04 under 640 w/m2 light intensity with 1000 µg/mL of Ag-TiO2. During the process of inactivating bacteria, the cell membranes of bacterial was destructed and thus decreasing the activity of enzymes and releasing the cell contents, due to the generation of reactive oxygen species (O2•- and •OH) and thermal effect. Spectral regulation has the greatest impact on the sterilization efficiency of MnO2-TiO2, which reduces the probability of photocatalytic materials being excited.

Analysis of radon mitigation methods: 10-year review.

Exposure to the radon gas within a building can result in an increased risk of lung cancer. To minimise the health risk, indoor radon concentrations can be reduced using well-established mitigation methods. The performance of various radon reduction methods, their combination as well as other factors that can impact the efficiency of radon mitigation, were analysed using data collected from approximately 2800 dwellings that had installed radon mitigation techniques during the period 2007-2017. As demonstrated previously (Hodgson 2011), active methods are the most effective at reducing high concentrations of radon to below the Action and Target Levels (200 Bq m-3and 100 Bq m-3respectively). Reduction factors of up to 5.5 using single active methods and 8.3 using a combination of active methods were estimated in this study. For indoor radon levels greater than 1 000 Bq m-3, the Active Sump remained the most efficient technique, with the Active Underfloor Ventilation being the second most effective method. Passive methods alone or in combination with other passive methods offered moderate reductions at high radon concentration. Of the passive methods, Underfloor Ventilation was found to have the highest performance with a reduction factor of 1.8. The conclusions of this study should be used to update guidance for stakeholders including householders, contractors, radon awareness campaigns and the UKradon.org website.

Bauen mit Holz ­ Empfehlungen für eine gute Raumluftqualität : Mitteilung der Kommission Innenraumlufthygiene (IRK).

Wood is a sustainable and widely applicable building material. Wood products emit gaseous substances into the indoor air, which is why they should meet the same indoor air quality requirements as any other building product used indoors. The Commission on Indoor Air Hygiene (IRK) provides advice on how to ensure healthy indoor living conditions in the presence of wood products. Important requirements are the selection of low-emission woods and wood-based materials, compliance with health-related assessment standards, and a ventilation concept that is tailored to the usage and emission sources in the building. When considering these guidelines, wood and wood-based materials can be successfully used both in existing buildings and in newly constructed, airtight buildings with low energy requirements.

Ventilation Improvements Among K-12 Public School Districts - United States, August-December 2022.

Improving ventilation has been one of several COVID-19 prevention strategies implemented by kindergarten through grade 12 (K-12) schools to stay open for safe in-person learning. Because transmission of SARS-CoV-2 occurs through inhalation of infectious viral particles, it is important to reduce the concentration of and exposure time to infectious aerosols (1-3). CDC examined reported ventilation improvement strategies among U.S. K-12 public school districts using telephone survey data collected during August-December 2022. Maintaining continuous airflow through school buildings during active hours was the most frequently reported strategy by school districts (50.7%); 33.9% of school districts reported replacement or upgrade of heating, ventilation, and air conditioning (HVAC) systems; 28.0% reported installation or use of in-room air cleaners with high-efficiency particulate air (HEPA) filters; and 8.2% reported installation of ultraviolet (UV) germicidal irradiation (UVGI) devices, which use UV light to kill airborne pathogens, including bacteria and viruses. School districts in National Center for Education Statistics (NCES) city locales, the West U.S. Census Bureau region, and those designated by U.S. Census Bureau Small Area Income Poverty Estimates (SAIPE) as high-poverty districts reported the highest percentages of HVAC system upgrades and HEPA-filtered in-room air cleaner use, although 28%-60% of all responses were unknown or missing. Federal funding remains available to school districts to support ventilation improvements. Public health departments can encourage K-12 school officials to use available funding to improve ventilation and help reduce transmission of respiratory diseases in K-12 settings.

HEPA filtration intervention in classrooms may improve some students' asthma.

OBJECTIVE: The School Inner-City Asthma Intervention Study 2 (SICAS 2) tested interventions to reduce exposures in classrooms of students with asthma. The objective of this post-hoc analysis was limited to evaluating the effect of high-efficiency particulate (HEPA) filtration interventions on mold levels as quantified using the Environmental Relative Moldiness Index (ERMI) and the possible improvement in the students' asthma, as quantified by spirometry testing. METHODS: Pre-intervention dust samples were collected at the beginning of the school year from classrooms and corresponding homes of students with asthma (n = 150). Follow-up dust samples were collected in the classrooms at the end of the HEPA or Sham intervention. For each dust sample, ERMI values and the Group 1 and Group 2 mold levels (components of the ERMI metric) were quantified. In addition, each student's lung function was evaluated by spirometry testing, specifically the percentage predicted forced expiratory volume at 1 sec (FEV1%), before and at the end of the intervention. RESULTS: For those students with a higher Group 1 mold level in their pre-intervention classroom than home (n = 94), the FEV1% results for those students was significantly (p < 0.05) inversely correlated with the Group 1 level in their classrooms. After the HEPA intervention, the average Group 1 and ERMI values were significantly lowered, and the average FEV1% test results significantly increased by an average of 4.22% for students in HEPA compared to Sham classrooms. CONCLUSIONS: HEPA intervention in classrooms reduced Group 1 and ERMI values, which corresponded to improvements in the students' FEV1% test results.

Childhood asthma and household exposures to nitrogen dioxide and fine particles: a triple-crossover randomized intervention trial.

OBJECTIVE: Triple-crossover randomized controlled intervention trial to test whether reduced exposure to household NO2 or fine particles results in reduced symptoms among children with persistent asthma. METHODS: Children (n = 126) aged 5-11 years with persistent asthma living in homes with gas stoves and levels of NO2 15 ppb or greater recruited in Connecticut and Massachusetts (2015-2019) participated in an intervention involving three air cleaners configured for: (1) NO2 reduction: sham particle filtration and real NO2 scrubbing; (2) particle filtration: HEPA filter and sham NO2 scrubbing; (3) control: sham particle filtration and sham NO2 scrubbing. Air cleaners were randomly assigned for 5-week treatment periods using a three-arm crossover design. Outcome was number of asthma symptom-days during final 14 days of treatment. Treatment effects were assessed using repeated measures, linear mixed models. RESULTS: Measured NO2 was lower (by 4 ppb, p < .0001) for NO2-reducing compared to control or particle-reducing treatments. NO2-reducing treatment did not reduce asthma morbidity compared to control. In analysis controlling for measured NO2, there were 1.8 (95% CI -0.3 to 3.9, p = .10) fewer symptom days out of 14 in the particle-reducing treatment compared to control. CONCLUSIONS: It remains unknown if using an air cleaner alone can achieve levels of NO2 reduction large enough to observe reductions in asthma symptoms. We observed that in small, urban homes with gas stoves, modest reductions in asthma symptoms occurred using air cleaners that remove fine particles. An intervention targeting exposures to both NO2 and fine particles is complicated and further research is warranted. REGISTRATION NUMBER: NCT02258893.

Building parameters linked with indoor transmission of SARS-CoV-2.

The rapid spread of Coronavirus Disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emphasized the importance of understanding and adapting to the indoor remediation of transmissible diseases to decrease the risk for future pandemic threats. While there were many precautions in place to hinder the spread of COVID-19, there has also been a substantial increase of new research on SARS-CoV-2 that can be utilized to further mitigate the transmission risk of this novel virus. This review paper aims to identify the building parameters of indoor spaces that could have considerable influence on the transmission of SARS-CoV-2. The following building parameters have been identified and analyzed, emphasizing their link with the indoor transmission of SARS-CoV-2: temperature and relative humidity, temperature differences between rooms, ventilation rate and access to natural ventilation, occupant density, surface type and finish, airflow direction and speed, air stability, indoor air pollution, central air conditioning systems, capacity of air handling system and HVAC filter efficiency, edge sealing of air filters, room layout and interior design, and compartmentalization of interior space. This paper also explains the interactions of SARS-CoV-2 with indoor environments and its persistence. Furthermore, the modifications of the key building parameters have been discussed for controlling the transmission of SARS-CoV-2 in indoor spaces. Understanding the information provided in this paper is crucial to develop effective health and safety measures that will aid in infection prevention.

Effects of a household air pollution intervention using liquefied petroleum gas stoves, continuous fuel distribution and behavioural messaging on dietary and sodium intake of adult women in Puno, Peru: a randomised controlled trial.

OBJECTIVE: Household air pollution (HAP) is a widespread environmental exposure worldwide. While several cleaner fuel interventions have been implemented to reduce personal exposures to HAP, it is unclear if cooking with cleaner fuels also affects the choice of meals and dietary intake. DESIGN: Individually randomised, open-label controlled trial of a HAP intervention. We aimed to determine the effect of a HAP intervention on dietary and Na intake. Intervention participants received a liquefied petroleum gas (LPG) stove, continuous fuel delivery and behavioural messaging during 1 year whereas control participants continued with usual cooking practices that involved the use of biomass-burning stoves. Dietary outcomes included energy, energy-adjusted macronutrients and Na intake at baseline, 6 months and 12 months post-randomisation using 24-h dietary recalls and 24-h urine. We used t-tests to estimate differences between arms in the post-randomisation period. SETTING: Rural settings in Puno, Peru. PARTICIPANTS: One hundred women aged 25-64 years. RESULTS: At baseline, control and intervention participants were similar in age (47·4 v. 49·5 years) and had similar daily energy (8894·3 kJ v. 8295·5 kJ), carbohydrate (370·8 g v. 373·3 g) and Na intake (4·9 g v. 4·8 g). One year after randomisation, we did not find differences in average energy intake (9292·4 kJ v. 8788·3 kJ; P = 0·22) or Na intake (4·5 g v. 4·6 g; P = 0·79) between control and intervention participants. CONCLUSIONS: Our HAP intervention consisting of an LPG stove, continuous fuel distribution and behavioural messaging did not affect dietary and Na intake in rural Peru.

Comprehensive interventions to reduce occupational hazards among medical staff in the pathology department of five primary hospitals.

OBJECTIVE: To explore comprehensive interventions to reduce occupational hazards among medical staff in the pathology department of five primary hospitals. METHODS: The indoor air quality in the pathology department of five primary hospitals and the health status of staff were investigated and analyzed. Formaldehyde and benzene concentrations in the technical and diagnostic rooms of the pathology departments were analyzed before and after comprehensive interventions. The Environmental Protection Agency risk assessment paradigm was used to assess the health risks from occupational exposure to benzene and formaldehyde. Consequently, considering the local environment, targeted comprehensive intervention measures were developed, including optimizing management, raising awareness, updating equipment, and replacing reagents. RESULTS: Eye discomfort was higher among technicians in the pathology department than among clinical medical staff (P < 0.05). Before comprehensive interventions, formaldehyde concentrations were higher in the technical room than in the diagnostic room at the five primary hospitals (P < 0.05). However, compared to before interventions, formaldehyde and benzene concentrations in both rooms were significantly lower after comprehensive interventions. Furthermore, although medium risks of occupational exposure to benzene and formaldehyde remained in both rooms before and after comprehensive interventions, the risk values before interventions were higher than after comprehensive interventions. The staff of the technical rooms showed higher risk values that those of the diagnostic rooms before and after comprehensive interventions. Similarly, although hazard quotient (HQ) values for occupational exposure to benzene and formaldehyde were < 1 in both the technical and diagnostic rooms before and after comprehensive interventions, with lower noncarcinogenic risks, the values were higher before than after comprehensive interventions. Moreover, staff in the technical room had higher HQ values before and after comprehensive interventions than those in the diagnostic room. The use of environmentally friendly reagents for the preparation of frozen sections was effective. CONCLUSION: Comprehensive interventions significantly reduced occupational hazards among staff at the pathology department of five primary hospitals, which is of great practical significance to protect the health of staff.

In former smokers with COPD, HEPA and carbon filter air cleaners improved moderate exacerbations but not QoL.

SOURCE CITATION: Hansel NN, Putcha N, Woo H, et al. Randomized clinical trial of air cleaners to improve indoor air quality and chronic obstructive pulmonary disease health: results of the CLEAN AIR study. Am J Respir Crit Care Med. 2022;205:421-30. 34449285.

From Raising Awareness to a Behavioural Change: A Case Study of Indoor Air Quality Improvement Using IoT and COM-B Model.

The topic of indoor air pollution has yet to receive the same level of attention as ambient pollution. We spend considerable time indoors, and poorer indoor air quality affects most of us, particularly people with respiratory and other health conditions. There is a pressing need for methodological case studies focusing on informing households about the causes and harms of indoor air pollution and supporting changes in behaviour around different indoor activities that cause it. The use of indoor air quality (IAQ) sensor data to support behaviour change is the focus of our research in this paper. We have conducted two studies-first, to evaluate the effectiveness of the IAQ data visualisation as a trigger for the natural reflection capability of human beings to raise awareness. This study was performed without the scaffolding of a formal behaviour change model. In the second study, we showcase how a behaviour psychology model, COM-B (Capability, Opportunity, and Motivation-Behaviour), can be operationalised as a means of digital intervention to support behaviour change. We have developed four digital interventions manifested through a digital platform. We have demonstrated that it is possible to change behaviour concerning indoor activities using the COM-B model. We have also observed a measurable change in indoor air quality. In addition, qualitative analysis has shown that the awareness level among occupants has improved due to our approach of utilising IoT sensor data with COM-B-based digital interventions.

Cleaning technologies integrated in duct flows for the inactivation of pathogenic microorganisms in indoor environments: A critical review of recent innovations and future challenges.

Pathogenic microorganisms are a major concern in indoor environments, particularly in sensitive facilities such as hospitals, due to their potential to cause nosocomial infections. This study evaluates the concentration of airborne bacteria and fungi in the University Hospital Complex of Albacete (Spain), comparing the results with recent literature. Staphylococcus is identified as the most prevalent bacterial genus with a percentage distribution of 35%, while Aspergillus represents the dominant fungal genus at 34%. The lack of high Technology Readiness Levels (TRL 6, TRL 7) for effective indoor air purification requires research efforts to bridge this knowledge gap. A screening of disinfection technologies for pathogenic airborne microorganisms such as bacteria and fungi is conducted. The integration of filtration, irradiation or and (electro)chemical gas treatment systems in duct flows is discussed to enhance the design of the air-conditioning systems for indoor air purification. Concerns over microbial growth have led to recent studies on coating commercial fibrous air filters with antimicrobial particles (silver nanoparticles, iron oxide nanowires) and polymeric materials (polyaniline, polyvinylidene fluoride). Promising alternatives to traditional short-wave UV-C energy for disinfection include LED and Far-UVC irradiation systems. Additionally, research explores the use of TiO2 and TiO2 doped with metals (Ag, Cu, Pt) in filters with photocatalytic properties, enabling the utilization of visible or solar light. Hybrid photocatalysis, combining TiO2 with polymers, carbon nanomaterials, or MXene nanomaterials, enhances the photocatalytic process. Chemical treatment systems such as aerosolization of biocidal agents (benzalkonium chloride, hydrogen peroxide, chlorine dioxide or ozone) with their possible combination with other technologies such as adsorption, filtration or photocatalysis, are also tested for gas disinfection. However, the limited number of studies on the use of electrochemical technology poses a challenge for further investigation into gas-phase oxidant generation, without the formation of harmful by-products, to raise its TRL for effectively inactivating airborne microorganisms in indoor environments.

[Study on revision of standard limits for benzene in"Standards for indoor air quality（GB/T 18883-2022）"in China].

Benzene, as a major indoor pollutant, has received widespread attention. In order to better control indoor benzene pollution and protect people's health, the limit value of benzene in the"Standards for indoor air quality (GB/T 18883-2022)'' was reduced from 0.11 mg/m3 to 0.03 mg/m3. This study reviewed and discussed the relevant technical contents of the determination of benzene limit value, including the exposure status of benzene, health effects, and derivation of the limit value. It also proposed prospects for the future direction of formulating indoor air benzene standards.