Publications by authors named "Timothy V Larson"

Introduction: Air pollution is linked with poor neurodevelopment in high-income countries. Comparable data are scant for low-income countries, where exposures are higher. Longitudinal pregnancy cohort studies are optimal for individual exposure assessment during critical windows of brain development and examination of neurodevelopment.

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Background: Exposure to air pollution is associated with worldwide morbidity and mortality. Diesel exhaust (DE) emissions are important contributors which induce vascular inflammation and metabolic disturbances by unknown mechanisms. We aimed to determine molecular pathways activated by DE in the liver that could be responsible for its cardiometabolic toxicity.

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Background: In contrast to fine particles, less is known of the inflammatory and coagulation impacts of coarse particulate matter (, particulate matter with aerodynamic diameter ). Toxicological research suggests that these pathways might be important processes by which impacts health, but there are relatively few epidemiological studies due to a lack of a national monitoring network.

Objectives: We used new spatiotemporal exposure models to examine associations of both 1-y and 1-month average concentrations with markers of inflammation and coagulation.

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Background: Ultrafine particles (UFP) are unregulated air pollutants abundant in aviation exhaust. Emerging evidence suggests that UFPs may impact lung health due to their high surface area-to-mass ratio and deep penetration into airways. This study aimed to assess long-term exposure to airport-related UFPs and lung cancer incidence in a multiethnic population in Los Angeles County.

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Background: While epidemiologic evidence links higher levels of exposure to fine particulate matter (PM) to decreased cognitive function, fewer studies have investigated links with traffic-related air pollution (TRAP), and none have examined ultrafine particles (UFP, ≤100 nm) and late-life dementia incidence.

Objective: To evaluate associations between TRAP exposures (UFP, black carbon [BC], and nitrogen dioxide [NO]) and late-life dementia incidence.

Methods: We ascertained dementia incidence in the Seattle-based Adult Changes in Thought (ACT) prospective cohort study (beginning in 1994) and assessed ten-year average TRAP exposures for each participant based on prediction models derived from an extensive mobile monitoring campaign.

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Mobile monitoring is increasingly used to assess exposure to traffic-related air pollutants (TRAPs), including ultrafine particles (UFPs). Due to the rapid spatial decrease in the concentration of UFPs and other TRAPs with distance from roadways, mobile measurements may be non-representative of residential exposures, which are commonly used for epidemiologic studies. Our goal was to develop, apply, and test one possible approach for using mobile measurements in exposure assessment for epidemiology.

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Inhaled particles and gases can harm health by promoting chronic inflammation in the body. Few studies have investigated the relationship between outdoor air pollution and inflammation by race and ethnicity, socioeconomic status, and lifestyle risk factors. We examined associations of particulate matter (PM) and other markers of traffic-related air pollution with circulating levels of C-reactive protein (CRP), a biomarker of systemic inflammation.

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Article Synopsis
  • Advances in air quality monitoring and prediction are essential for assessing long-term exposure to pollutants and understanding health impacts.
  • The article proposes a conceptual framework for new monitoring designs that utilize both mobile and stationary methods, emphasizing the importance of cost-effective tools.
  • Current studies often focus on land use for monitoring site selection, and future research should aim to enhance residence-based monitoring to optimize data collection and improve exposure assessments.
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Short-term mobile monitoring campaigns are increasingly used to assess long-term air pollution exposure in epidemiology. Little is known about how monitoring network design features, including the number of stops and sampling temporality, impacts exposure assessment models. We address this gap by leveraging an extensive mobile monitoring campaign conducted in the greater Seattle area over the course of a year during all days of the week and most hours.

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The Healthy Air, Healthy Schools Study was established to better understand the impact of ultrafine particles (UFPs) on indoor air quality in communities surrounding Seattle-Tacoma (Sea-Tac) International Airport. The study team took multipollutant measurements of indoor and outdoor air pollution at five participating school locations to estimate infiltration indoors. The schools participating in this project were located within a 7-mile radius of Sea-Tac International Airport and within 0.

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Background: Based on human and animal experimental studies, exposure to ambient carbon monoxide (CO) may be associated with cardiovascular disease outcomes, but epidemiological evidence of this link is limited. The number and distribution of ground-level regulatory agency monitors are insufficient to characterize fine-scale variations in CO concentrations.

Objectives: To develop a daily, high-resolution ambient CO exposure prediction model at the city scale.

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Article Synopsis
  • - The study highlights the growing trend of short-term mobile monitoring for estimating long-term air pollution levels, emphasizing the importance of balanced sampling to avoid biased data.
  • - By simulating different monitoring designs using nitrogen oxides data from California, researchers found that a year-round Balanced Design provided the most accurate annual averages compared to more limited designs focused on rush or business hours.
  • - The findings stress that maintaining a temporally-balanced sampling approach is essential for accurate epidemiological exposure assessments in air quality studies.
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Growing evidence links traffic-related air pollution (TRAP) to adverse health effects. We designed an innovative and extensive mobile monitoring campaign to characterize TRAP exposure levels for the Adult Changes in Thought (ACT) study, a Seattle-based cohort. The campaign measured particle number concentration (PNC) to capture ultrafine particles (UFP), black carbon (BC), nitrogen dioxide (NO), fine particulate matter (PM), and carbon dioxide (CO) at 309 roadside sites within a large, 1200 land km (463 mi) area representative of the cohort.

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Introduction: Air pollution has been linked to preterm birth (PTB) while findings for noise exposure have been mixed. Few studies - none considering airports - have investigated combined exposures. We explore the relationship between joint exposure to airport-related noise, airport ultrafine particles (UFP), and vehicle traffic-related air pollution (TRAP) on risk of PTB near Los Angeles International Airport (LAX).

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High-resolution, high-quality exposure modeling is critical for assessing the health effects of ambient PM in epidemiological studies. Using sparse regulatory PM measurements as principal model inputs may result in two issues in exposure prediction: (1) they may affect the models' accuracy in predicting PM spatial distribution; (2) the internal validation based on these measurements may not reliably reflect the model performance at locations of interest (e.g.

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Article Synopsis
  • Air pollution, specifically long-term exposure to fine particulate matter, may increase the risk of developing dementia, according to a study conducted on a population-based cohort in the United States.
  • The research utilized extensive data from the Adult Changes in Thought (ACT) study, analyzing health outcomes from 1978 to 2018 and specifically focusing on a 10-year average of exposure to fine particulate matter.
  • Findings revealed that each increase in fine particulate matter exposure was associated with a 16% higher risk of all-cause dementia, highlighting the importance of controlling for various confounding factors when assessing these risks.
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We designed and built a network of monitors for ambient air pollution equipped with low-cost gas sensors to be used to supplement regulatory agency monitoring for exposure assessment within a large epidemiological study. This paper describes the development of a series of hourly and daily field calibration models for Alphasense sensors for carbon monoxide (CO; CO-B4), nitric oxide (NO; NO-B4), nitrogen dioxide (NO; NO2-B43F), and oxidizing gases (OX-B431)-which refers to ozone (O) and NO. The monitor network was deployed in the Puget Sound region of Washington, USA, from May 2017 to March 2019.

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Ultrafine particles (UFP; diameter less than or equal to 100 nm) may reach the brain via systemic circulation or the olfactory tract and have been implicated in the risk of brain tumors. The effects of airport-related UFP on the risk of brain tumors are not known. Here we determined the association between airport-related UFP and risk of incident malignant brain cancer ( = 155) and meningioma ( = 420) diagnosed during 16.

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Article Synopsis
  • The review highlights the evolution of exposure assessment in air pollution studies, focusing on spatiotemporal techniques developed during the MESA Air project, which allow for a detailed understanding of pollution variations in urban areas.
  • Recent advancements in modeling techniques enable the prediction of pollutant levels, such as PM, nitrogen oxides, and ozone, at specific locations and timeframes (e.g., residential addresses over two weeks) across the contiguous USA from 1980 to now.
  • These modern models improve upon past methods by using better statistical approaches and integrating diverse data sources, leading to more accurate insights into the health impacts of air pollution throughout people's lives.
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Mobile monitoring is increasingly employed to measure fine spatial-scale variation in air pollutant concentrations. However, mobile measurement campaigns are typically conducted over periods much shorter than the decadal periods used for modeling chronic exposure for use in air pollution epidemiology. Using the regions of Los Angeles and Baltimore and the time period from 2005 to 2014 as our modeling domain, we investigate whether including mobile or stationary passive sampling device (PSD) monitoring data collected over a single 2-week period in one or two seasons using a unified spatio-temporal air pollution model can improve model performance in predicting NO and NO concentrations throughout the 9-year study period beyond what is possible using only routine monitoring data.

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The Mobile ObserVations of Ultrafine Particles study was a two-year project to analyze potential air quality impacts of ultrafine particles (UFPs) from aircraft traffic for communities near an international airport. The study assessed UFP concentrations within 10 miles of the airport in the directions of aircraft flight. Over the course of four seasons, this study conducted a mobile sampling scheme to collect time-resolved measures of UFP, CO, and black carbon (BC) concentrations, as well as UFP size distributions.

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Although the exposure to PM has serious health implications, indoor PM monitoring is not a widely applied practice. Regulations on the indoor PM level and measurement schemes are not well established. Compared to other indoor settings, PM prediction models for large office buildings are particularly lacking.

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Article Synopsis
  • Exposure to diesel exhaust (DE) leads to a significant decrease in the ratio of reduced to oxidized glutathione (GSH/GSSG) and a notable increase in IL-6 mRNA levels in healthy adults, indicating oxidative stress.
  • A study involving 19 nonsmoking adults demonstrated that inhaling DE negatively impacts antioxidant levels, but pre-exposure antioxidant supplementation did not significantly protect against these effects.
  • The results underscore that acute exposure to traffic-related air pollution can cause oxidative stress, which may contribute to cardiovascular and respiratory diseases, emphasizing the need for further research in this area.
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Accurate predictions of pollutant concentrations at new locations are often of interest in air pollution studies on fine particulate matters (PM), in which data is usually not measured at all study locations. PM is also a mixture of many different chemical components. Principal component analysis (PCA) can be incorporated to obtain lower-dimensional representative scores of such multi-pollutant data.

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Article Synopsis
  • We propose a cost-effective, passive method for monitoring long-term light-absorbing carbon pollution indoors, using digital images to estimate changes in surface reflectance.
  • Preliminary lab tests and indoor environmental assessments across 20 locations showed strong reproducibility of results (0.99) and effective detection limits for monitoring over several months in homes using solid fuels.
  • Although the method demonstrates high precision, further validation with reliable measurements is necessary to confirm its overall accuracy.
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