Incubator-based active noise control device: comparison to ear covers and noise reduction zone quantification.

BACKGROUND: Noise exposure in the neonatal intensive care unit (NICU) is consistently higher than current recommendations. This may adversely affect neonatal sleep, weight gain, and overall health. We sought to evaluate the effect of a novel active noise control (ANC) system. METHODS: An ANC device's noise reduction performance was compared to that of adhesively affixed foam ear covers in response to alarm and voice sounds in a simulated NICU environment. The zone of noise reduction of the ANC device was quantified with the same set of alarm and voice sounds. RESULTS: The ANC device provided greater noise reduction than the ear covers in seven of the eight sound sequences tested in which a noise reduction greater than the just noticeable difference was achieved. For noise in the 500 Hz octave band, the ANC device exhibited consistent noise reduction throughout expected patient positions. It provided better performance for noise below 1000 Hz than above 1000 Hz. CONCLUSIONS: The ANC device provided generally superior noise reduction to the ear covers and provided a zone of noise reduction throughout the range where an infant would be placed within an incubator. Implications for patient sleep and weight gain are discussed. IMPACT: Active noise control device can effectively reduce noise inside an infant incubator due to bedside device alarms. This is the first analysis of an incubator-based active noise control device and comparison to adhesively affixed silicone ear covers. A non-contact noise reduction device may be an appropriate means of reducing noise exposure of the hospitalized preterm infant.

Dental drill noise reduction using a commercially-available earplug device.

AIM: The dental handpiece noise in a dental surgery is concerning to both patients and staff as a major cause of dental phobia in patients and potential hearing loss in clinical staff. High-frequency noise generated by dental handpieces is considered to be the worst of the many noises in a dental clinic. Methods to reduce this noise have been proposed and either passive or active noise reduction headphones are often suggested. However, in a dental surgery environment, the need for good verbal communication with the patient needs to be maintained. As a result, this paper aims to evaluate one proprietary anti-noise device considered suitable for this specific purpose. METHODS: Lab-based experiments were set up and carried out to evaluate QuietOn, using GRAS 43AG-1 Ear and Cheek Simulator to mimic a section of the human head and ear to represent the acoustic characteristics of an actual ear. Two types of dental drill noise recordings, one for electric motor-driven and another one for air turbine-driven, were played back through high-definition speakers. Sound data captured by the simulator are then visualised and plotted using MATLAB for analysis. MAIN FINDINGS: QuietOn is effective at low frequencies (< 1kHz). However, when dealing with high-frequency noise such as dental handpieces it is ineffective yet subdues verbal communication. CONCLUSIONS: Further development of passive or active noise cancellation earplugs is still needed to target dental handpiece noise while maintaining verbal communication.

Sound and Light Levels in a General Intensive Care Unit Without Windows to Provide Natural Light.

BACKGROUND: Appropriate levels and patterns of sound and light in an intensive care room help to maintain the patient's normal physiological functions. High sound levels can disrupt the patient's normal sleep architecture, cause hearing deficits, and induce the onset of delirium. Intensive care unit patients frequently report poor sleep, partly due to the environment. OBJECTIVES: An observational pilot prospective study was designed to record sound pressure and light pollution levels in an Italian intensive care unit, without windows to provide natural light. METHOD: Sound levels were measured in decibel A (dBA) every 10 seconds. Sound data were analyzed for sound peak, defined as the number of times sound levels exceeded 45, 50, 60, 65, 70, 75, 80, and 85 dBA. Light measures were taken every 10 seconds on a continuous basis. Light data were analyzed for light "peaks," defined as the number of times light levels exceeded 100, 200, 300, 400, and 500 lux. RESULTS: The overall median sound level during the study period was equal to 54.60 (interquartile range [IQR], 51.70-57.70) dBA. The daytime median sound level was 56.00 (IQR, 53.00-59.50) dBA, and the nighttime median was 53.00 (IQR, 49.50-55.20) dBA (P < .001). The overall median light level was equal to 114 (IQR, 0-225) lux. The daytime median light level was 184 (IQR, 114-293) lux, and the nighttime median was 0 (IQR, 0-50) lux (P < .001). With respect to room lighting, rooms were observed to have "no lights on" 12.6% of daytime and 41% of nighttime. DISCUSSION: The sound levels recorded in our sample demonstrated that peaks >45 dBA during daytime and nighttime are, respectively, equal to 99.9% and 98.6% of all readings. The Environmental Protection Agency/World Health Organization recommended thresholds for both day (45 dBA) and night (35 dBA). Sound levels reached "toxic levels" when sound-generating activities were performed by nurses and physicians.

The Sound of a Circular City: Towards a Circularity-Driven Quietness.

The circular economy paradigm can be beneficial for urban sustainability by eliminating waste and pollution, by circulating products and materials and by regenerating nature. Furthermore, under an urban circular development scheme, environmental noise can be designed out. The current noise control policies and actions, undertaken at a source-medium-receiver level, present a linearity with minimum sustainability co-benefits. A circular approach in noise control strategies and in soundscape design could offer numerous ecologically related co-benefits. The global literature documenting the advantages of the implementation of circular economy in cities has highlighted noise mitigation as a given benefit. Research involving circular economy actions such as urban green infrastructure, green walls, sustainable mobility systems and electro-mobility has acknowledged reduced noise levels as a major circularity outcome. In this research paper, we highlight the necessity of a circularity and bioeconomy approach in noise control. To this end, a preliminary experimental noise modeling study was conducted to showcase the acoustic benefits of green walls and electric vehicles in a medium-sized urban area of a Mediterranean island. The results indicate a noise level reduction at 4 dB(A) when simulating the introduction of urban circular development actions.

Active Indoor Soundscape Design: A Case Study of Ceramic Passive Amplifiers.

Indoor soundscape research has developed rapidly in recent years, with the aim of improving the single indoor noise reduction method and people's acoustic comfort. However, practical solutions to promote the generation of positive indoor soundscapes are still insufficient. The purpose of this study was to explore the improvement effect of ceramic passive amplifiers on the indoor soundscape and the relationship between the improvement effect and different amplifier shapes. Objective sound pressure level (SPL) values and subjective soundscape perception were measured for 10 ceramic passive amplifiers based on the soundscape, mainly using a comparative method. Ten sample amplifiers were compared with the acoustic data of the original open-plan studio environment, and then with an electronic sound amplifier. The results show that ceramic passive amplifiers can improve the quality of the indoor soundscape by creating sound scenes with appropriate loudness. Regarding non-acoustic aspects, the shape and materials of ceramic passive amplifiers play a positive role in emotional guidance.

Assessment of Real-Time Active Noise Control Devices in Dental Treatment Conditions.

Dental clinics are exposed to various uncomfortable noises. The aim of this study was to quantify the effectiveness of active noise control devices in dental treatment conditions. Two types of commercial headsets (Airpods Pro, QC30) and two types of dental headsets (Alltalk, Quieton Dental) were used for the experiment. Three sounds (high-speed handpiece, low-speed handpiece, and suction system) were measured at three different distances from the dental teeth model, typodont. The distances of 10, 40, and 70 cm reflected the positions of the patient, assistant, and practitioner's ears, respectively. Sound analysis was performed, and the significance of differences in the maximum noise level using each device was determined with the Kruskal−Wallis test. Dental noise was characterized by the peak in sound pressure level (SPL) at 4−5 kHz and >15 kHz frequencies. The commercial headsets efficiently blocked 1 kHz and 10 kHz of noise. The dental headsets efficiently reduced 4−6 and >15 kHz noise. Quieton had the highest maximum SPL in all situations and positions among the four devices. For a better dental clinic, however, active noise control devices more suitable for the characteristics of dental noise should be developed.

[Reducing noise nuisance in open-plan office rooms by masking unwanted sounds with pyramid-shaped sound columns]. / Zmniejszenie uciazliwosci halasu w biurowych pomieszczeniach open space przez maskowanie dzwieków niepozadanych kolumnami dzwiekowymi w ksztalcie piramid.

BACKGROUND: In order to obtain appropriate, acoustic conditions of working environment in open plan offices, it is necessary to apply quite a large acoustic treatment in these rooms (e.g., to achieve reverberation time 0.2-0.4 s). However, in cases where the background noise levels in rooms are very low (A-weighted sound pressure level <30 dB), then acoustic treatment alone may be insufficient. In such cases, it may be necessary to use a sound system that generate an "artificial" background noise (sound masking system). It is important that the sound masking system must mask the sound in many workplaces. Therefore, sound masking systems contain a large number of sound sources (loudspeakers), evenly distributed throughout the room. Most often, these loudspeakers are placed in a sound-absorbing suspended ceiling. MATERIAL AND METHODS: The article considers the possibility of reducing the number of sound masking sources by using 4-loudspeakers columns. These columns use speakers with much smaller dimensions and less power. The shape of the columns and the arrangement of the loudspeakers in the columns result in a directional radiation pattern that allows for a more even distribution of the masking sound in a room. The article provides the criterion of obtaining a uniform masking sound in the open plan offices. These criteria relate to obtaining appropriate masking sound parameters in the working area, and are based on the criterion value of the distraction distance of the room. RESULTS: The article provides the results of measurement tests of the uniformity of masking sound in the room with the use of the above-mentioned sound masking columns. CONCLUSIONS: It is possible to limit the number of standard masking sound sources in the rooms under consideration using pyramid-shaped sound columns with 4 loudspeakers are used. Med Pr. 2022;73(3):229-40.

New novel thermal insulation and sound-absorbing materials from discarded facemasks of COVID-19 pandemic.

Due to the COVID-19 pandemic, people were encouraged and sometimes required to wear disposable facemasks, which then are discarded creating an environmental problem. In this study, we aim at investigating novel ideas to recycle wasted facemasks in order to lower the environmental impact. An experimental study has been carried out to investigate the possibility of using discarded masks for thermal insulation and sound absorption. The wasted masks are simulated by new masks, which stripped off the nose clips, elastic ear loops and are heated to 120 °C for one hour to kill any biological contaminants. The masks are also melted to investigate their thermal insulation and sound absorption properties. Results show that the thermal conductivity coefficients of the loose and melted masks are 0.03555 and 0.08683 W/m K, respectively, at room temperature of about 25 °C. Results show also that the sound absorption coefficient for loose masks is above 0.6 for the frequency range 600-5000 Hz. The loose facemasks are found to be thermally stable up to 295 °C, elastic ear loops at 304.7 °C, and the composite (melted) facemasks at 330.0 °C using the thermo-gravimetric analysis. Characterization of the facemask's three-layer fibers and the composite (melted) samples is obtained using scanning electron microscopy (SEM). The three-point bending test is obtained for the composite specimens showing good values of flexural stress, flexural strain, and flexural elastic modulus. These results are promising about using such discarded masks as new thermal insulation and sound-absorbing materials for buildings replacing the synthetic or petrochemical insulation materials.

The Effect of a Quality Improvement Intervention on Sleep and Delirium in Critically Ill Patients in a Surgical ICU.

BACKGROUND: Delirium is a deleterious condition affecting up to 60% of patients in the surgical ICU (SICU). Few SICU-focused delirium interventions have been implemented, including those addressing sleep-wake disruption, a modifiable delirium risk factor common in critically ill patients. RESEARCH QUESTION: What is the effect on delirium and sleep quality of a multicomponent nonpharmacologic intervention aimed at improving sleep-wake disruption in patients in the SICU setting? STUDY DESIGN AND METHODS: Using a staggered pre-post design, we implemented a quality improvement intervention in two SICUs (general surgery or trauma and cardiovascular) in an academic medical center. After a preintervention (baseline) period, a multicomponent unit-wide nighttime (ie, efforts to minimize unnecessary sound and light, provision of earplugs and eye masks) and daytime (ie, raising blinds, promotion of physical activity) intervention bundle was implemented. A daily checklist was used to prompt staff to complete intervention bundle elements. Delirium was evaluated twice daily using the Confusion Assessment Method for the Intensive Care Unit. Patient sleep quality ratings were evaluated daily using the Richards-Campbell Sleep Questionnaire (RCSQ). RESULTS: Six hundred forty-six SICU admissions (332 baseline, 314 intervention) were analyzed. Median age was 61 years (interquartile range, 49-70 years); 35% of the cohort were women and 83% were White. During the intervention period, patients experienced fewer days of delirium (proportion ± SD of ICU days, 15 ± 27%) as compared with the preintervention period (20 ± 31%; P = .022), with an adjusted pre-post decrease of 4.9% (95% CI, 0.5%-9.2%; P = .03). Overall RCSQ-perceived sleep quality ratings did not change, but the RCSQ noise subscore increased (9.5% [95% CI, 1.1%-17.5%; P = .02). INTERPRETATION: Our multicomponent intervention was associated with a significant reduction in the proportion of days patients experienced delirium, reinforcing the feasibility and effectiveness of a nonpharmacologic sleep-wake bundle to reduce delirium in critically ill patients in the SICU. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03313115; URL: www.clinicaltrials.gov.

Multifunctional Textiles/Metal-Organic Frameworks Composites for Efficient Ultraviolet Radiation Blocking and Noise Reduction.

Ultraviolet radiation (UVR) and noise are the ubiquitous environmental hazards with considerable detrimental effects on the physiological and psychological health of humans. Exploiting efficient protective materials that can be extensively used in daily life for simultaneous anti-UVR and noise mitigation will be of crucial importance, but it is still a significant challenge in materials design. Herein, we developed a series of protective textiles for efficient anti-UVR and noise reduction via MOFs nanocrystal-modified cotton textiles. The formation of MOFs@cotton textiles was confirmed by using electron microscopy, X-ray diffraction, infrared spectroscopy, and X-ray photoelectron spectroscopy. The fabricated MOFs@cotton textiles exhibited substantial improvement in the UVR blocking and acoustic absorption properties compared to blank cotton textiles. Therefore, this work provides a good strategy for designing and preparing multifunctional protective textiles.

Analysis of the Sound Environment and the Sound Level in the Delivery Room in the First Hour of a Newborn's Life.

OBJECTIVE: The aim of the study was to analyse the sound environment and the range of sound levels recorded in the delivery room immediately after the birth of a newborn. MATERIALS AND METHODS: The research method was open observation combined with recording measurements of the sound intensity levels. The material was collected by means of an observation questionnaire. The research was conducted in 11 maternity hospitals in Warsaw. A total of 304 vaginal labours were analysed. RESULTS: The average sound level in the delivery room after the birth of a newborn was 58.03 ± 7.66 dB, and the sound intensity ranged from 40.30 dB to 78.0 dB. Staff conversations were the most common sources of noise. A statistically significant relationship between the number of people in the delivery room and sound intensity was observed. The number of people positively correlated with the average sound level (R=0.520, p<0.001). CONCLUSIONS: Based on the tests, it was found that the average sound level in the delivery room exceeded the recommended standards. The noise was mainly caused by the activity of staff. The present study indicates the need for staff education and the use of noise reduction procedures.

Efectos del ruido en la calidad vocal de docentes de instituciones educativas / Effects of noise on the vocal quality of educational institute teachers

Introducción: la investigación tuvo como objetivo identificar el efecto del ruido en la calidad vocal mediante el análisis acústico de la voz en docentes de instituciones educativas en Cúcuta, Norte de Santander. Métodos: se llevó a cabo un estudio descriptivo de enfoque cuantitativo, con una población total de 71 docentes, a quienes se les realizó: audiometría, análisis acústico de la voz, protocolo índice de incapacidad vocal y sonometría. Resultados: se encontró un promedio de ruido para cada área entre 62 y 65 dB y se identificó alteración en JITTER local a 25 docentes de los 57 evaluados. JITTER =0,307+0,015 edad-0,126 sexo-0,012 tiempo de servicio +0,018 horas trabajadas -0,008 ruido Análisis y discusión: en modelos de regresión el resultado fue R2=18,6% lo cual indica que, en conjunto, las variables independientes explican en un 18,6% la varia-bilidad que se presenta en la variable dependiente, JITTER. A pesar de que esta ecuación no es la mejor para fines predictivos, las relaciones que obtuvimos están en correspondencia con los postulados teóricos de la voz. Conclusiones: no hubo variabilidad en las mediciones del ruido. Sus porcentajes fueron homogéneos, esto impidió realizar un registro predictivo con el modelo de regresión. Sin embargo, la literatura indica que el ruido es un factor significativa-mente influyente en la calidad vocal cuando se ve acompañado de otros factores de exposición

Introduction: the objective of this research was to identify noise effect on vocal quality through acoustic analysis of the voice of teachers who work in educational institutions in Cúcuta, Norte de Santander. Methods: a descriptive study with a quantitative approach was carried out with a total po-pulation of 71 teachers, who underwent: audiometry, acoustic analysis of the voice, vocal disability index protocol and sonometry.Results: the average noise level found for each area ranged between 62 and 65 dB and an alteration in local JITTER in 25 of the 57 teachers evaluated was discovered. JITTER = 0.307 + 0.015 age-0.126 sex-0.012 service time +0.018 hours worked -0.008 noise. Analysis and discussion: in the regression models the result was R2 = 18.6%, which indica-tes that, as a whole, the independent variables explain 18.6% of the variability that occurs in the dep endent variable, JITTER. Although this equation is not the best for predictive purposes, the relationships we obtained are in correspondence with the voice theoretical postulates. Conclusions: there was no variability in noise measurements. Their percentages were ho-mogeneous, which prevented a predictive registration with the regression model. However, according to literature noise is a factor that significantly influences vocal quality as long as it is accompanied of other exposure factors.

Listening to Japanese Gardens: An Autoethnographic Study on the Soundscape Action Design Tool.

Landscape architecture and urban design disciplines could benefit from soundscape thinking in order to enhance experiential qualities in their projects, though the available tools are not yet fully developed nor tested. The present research aims to substantiate one of the available tools, Soundscape Actions, and thereby increase the understanding of soundscape design. The study focuses on the Japanese garden tradition, which is known for high preference ratings, tranquil qualities and consideration for sound and other sensory experiences. An autoethnographic approach was used to conduct field studies in 88 gardens in Japan, the majority of which are located in urban areas with potential noise disturbance. The studies are based on observations in situ, supported by video documentation, field recordings and readings of sound pressure levels (SPL). A total of 19 Soundscape Actions are described and discussed in the paper. They are structured around three main categories: localisation of functions, reduction of unwanted sounds and introduction of wanted sounds. The study provides concrete examples of how the tool can be used to enhance tranquil qualities, particularly focusing on small green spaces in dense urban settings, involving the (simultaneous) reduction of unwanted sounds and enhancement of wanted sounds/effects. The autoethnographic approach allowed for the phenomenological perspective to be brought forward, which contributed new insights regarding the design tool. The findings are discussed in relation to health and soundscape research, focusing on multisensory experiences, masking strategies and potentials for implementation and future developments of the design tool.

Quality Improvement Initiative to Reduce Nighttime Noise in a Transplantation and Cellular Therapy Unit.

Sleep is an essential biologic function vital for physiologic rest, healing, and emotional well-being. Sleep disruption is commonly seen in patients and caregivers with lengthy hospital stays such as patients undergoing hematopoietic stem cell transplantation and cellular therapy (TCT). Sleep disruption can lead to increased stress and fatigue, affecting caregivers' ability to support their loved one. The global aim of our quality improvement initiative was to improve sleep quality in TCT patients and caregivers. The smart aim of our project was to decrease nighttime hallway noise from 47 dB to 43 dB and decrease the number of overnight noise peaks greater than 60 dB from 865 to 432 in 6 months. Through a cross-sectional quantitative and qualitative evaluation of sleep we had previously identified poor sleep quality, and with a cross-sectional focus group analysis of patients, caregivers, and medical staff we identified the factors associated with poor sleep. Hallway noise was a major factor. A simplified failure mode analysis identified 4 main key drivers; unobtrusive nighttime cleaning process, nighttime awareness maintenance system, quiet nighttime nursing system, and reliable nighttime awareness system. Several plan-do-study-act interventions took place and were adopted. From January to June 2018 the overnight mean decibel level decreased from 47 dB to 44 dB (6% reduction). Overnight noise spikes above 60 dB decreased from a mean of 865 spikes to a mean of 463 spikes (46% reduction). With a quality improvement initiative, we identified the causes of hallway nighttime hospital unit noise that negatively impact sleep and through a team-based approach performed interventions that successfully mitigated these factors.

Is patient satisfaction related to patient reported sounds from ceramic on ceramic total hip arthroplasty? A study of 265 hips.

INTRODUCTION: The ideal method and implant to perform total hip arthroplasty (THA) is still a debated topic. Ceramic on ceramic (CoC) bearings have favourable wear properties, but squeaking has been reported as an unwanted side effect. We aimed to determine the rate of noise generation from CoC hips and investigate whether there is a relationship with patient satisfaction. METHODS: A total of 246 consecutive CoC bearing uncemented THA were retrospectively identified in a single institution. Post-operatively patients were sent a postal questionnaire to evaluate their reported sounds and satisfaction with their THA. Uni- and multi-variate analyses were performed to identify potential predictor variables for reported post-operative sounds. RESULTS: Questionnaires were returned by 172 patients (70% return rate). 24% reported sounds from their hips with 11% reporting a squeak. Median satisfaction levels were minimally, but significantly less for "noisy" (9/10) than "quiet" hips (10/10) (median difference = - 1, 95% CI - 2 to 0, p < 0.001). Compared to those with "noisy" hips, patients with "quiet" hips were 1.7 times (95% CI 1.3-2.5, p = 0.0002) more likely to report a "forgotten" hip. Younger age (p < 0.043) and increased anteversion (p < 0.021) were predictors for reported sounds. CONCLUSION: We have identified a high rate of "noisy" hips in this series of CoC THA with a significant inverse relationship between "noisy" hips and patient satisfaction levels. In our unit, we are moving towards the use of ceramic on cross-linked polyethylene bearings as a result of these findings and the excellent survivorship of this bearing combination.

Implementation of Quiet Areas in Sweden.

The notion of quiet areas has received increasing attention within the EU in recent years. The EU Environmental Noise Directive (END) of 2002 stipulates that member states should map existing quiet areas and formulate strategies to keep these quiet. Quiet areas could play an important role in balancing densified urban development by ensuring access to relative quietness and associated health benefits. This paper reports on a recent study investigating how the notion of quiet areas has been implemented in Sweden. The study, initiated by the Sound Environment Center in 2017, was carried out in two phases. In phase one, an overview of the current situation was obtained by scrutinizing regional and municipal mapping initiatives, aided by a short digital questionnaire sent out to all 290 municipalities in Sweden. This provided a general understanding and highlighted initiatives for further study in phase two. The results revealed that 41% (n = 118) of Sweden's municipalities include quiet areas in their general plans, but that significantly fewer of these have sophisticated strategies for implementation (n = 16; 6%). Moreover, the interest in quiet areas in municipalities does not seem to be directly related to the END, but is instead inspired by previous regional initiatives in Sweden. The study highlights a number of considerations and examples of how quiet areas are approached in Sweden today. In general, Sweden has come a long way in terms of identifying and mapping quiet areas, but more progress is needed in developing strategies to protect, maintain, and publicize quiet areas.

Are noise and air pollution related to the incidence of dementia? A cohort study in London, England.

OBJECTIVE: To investigate whether the incidence of dementia is related to residential levels of air and noise pollution in London. DESIGN: Retrospective cohort study using primary care data. SETTING: 75 Greater London practices. PARTICIPANTS: 130 978 adults aged 50-79 years registered with their general practices on 1 January 2005, with no recorded history of dementia or care home residence. PRIMARY AND SECONDARY OUTCOME MEASURES: A first recorded diagnosis of dementia and, where specified, subgroups of Alzheimer's disease and vascular dementia during 2005-2013. The average annual concentrations during 2004 of nitrogen dioxide (NO2), particulate matter with a median aerodynamic diameter ≤2.5 µm (PM2.5) and ozone (O3) were estimated at 20×20 m resolution from dispersion models. Traffic intensity, distance from major road and night-time noise levels (Lnight) were estimated at the postcode level. All exposure measures were linked anonymously to clinical data via residential postcode. HRs from Cox models were adjusted for age, sex, ethnicity, smoking and body mass index, with further adjustments explored for area deprivation and comorbidity. RESULTS: 2181 subjects (1.7%) received an incident diagnosis of dementia (39% mentioning Alzheimer's disease, 29% vascular dementia). There was a positive exposure response relationship between dementia and all measures of air pollution except O3, which was not readily explained by further adjustment. Adults living in areas with the highest fifth of NO2 concentration (>41.5 µg/m3) versus the lowest fifth (<31.9 µg/m3) were at a higher risk of dementia (HR=1.40, 95% CI 1.12 to 1.74). Increases in dementia risk were also observed with PM2.5, PM2.5 specifically from primary traffic sources only and Lnight, but only NO2 and PM2.5 remained statistically significant in multipollutant models. Associations were more consistent for Alzheimer's disease than vascular dementia. CONCLUSIONS: We have found evidence of a positive association between residential levels of air pollution across London and being diagnosed with dementia, which is unexplained by known confounding factors.