Ole Hertel

• DSc, PhD, MSc, BSc
• Vice-Dean for Outreach at Aarhus University

Background Epidemiologic studies have demonstrated that ambient concentrations of particulate matter < 2.5 μm (PM 2.5 ) are associated with reduced fecundability, the per cycle probability of conception. The specific constituents driving this association are unknown. Objectives We examined the association between ambient concentrations of PM 2.5 c...

This study assesses low-cost sensors (LCS) for mobile monitoring of air quality, which has thus far been scarcely investigated. NO2 and PM2.5 were measured using LCS and higher-grade instruments while driving across various environments in London (943 km) and northern Europe (2923 km), including urban areas, motorways, and tunnels. The data was cla...

This paper describes the DAnish Lagrangian Model (DALM), which is a new high-resolution air pollution model based on the concept of Lagrangian particles. The new model is developed from the simpler Gaussian plume-in-grid Urban Background Model (UBM) and is to be integrated with the DEHM/UBM/AirGIS modeling system, developed at Aarhus University. In...

Low-cost sensors (LCS) could help extend current air pollution monitoring programs by improving their density and time resolution. We evaluate rapid and hyperlocal pollution gradients in London using a network of LCS nodes and a Mobile Air Pollution Sensing (MAPS) car, focusing on NO2. The measurements were strongly correlated; the R2-value decreas...

Air pollution has been shown to significantly impact human health including cancer. Gastric and upper aerodigestive tract (UADT) cancers are common and increased risk has been associated with smoking and occupational exposures. However, the association with air pollution remains unclear. We pooled European subcohorts (N = 287,576 participants for g...

Ultrafine particles (UFPs) are airborne particles with a diameter of less than 100 nm. They are emitted from various sources, such as traffic, combustion, and industrial processes, and can have adverse effects on human health. Long-term mean ambient average particle size (APS) in the UFP range varies over space within cities, with locations near UF...

This article aims to assess the performance of Nord2000, RTN-96, and CNOSSOS-EU, the Nordic and European noise prediction standards, in predicting daily LAeq24h and Lden levels (dBA), by comparing them with measurements gathered over 76 days from the E45 motorway in Helsted, Central Jutland, Denmark. In addition, the article investigates the potent...

A widely used method for estimating fine scale long-term spatial variation in air pollution, especially for epidemiology studies, is land use regression (LUR) modeling using fixed off-road monitors. More recently, LUR models have been developed using data from mobile monitors that repeatedly measure road pollutants and mixed-effects modeling. Here,...

Aims: We provide an overview of nationwide environmental data available for Denmark and its linkage potentials to individual-level records with the aim of promoting research on the potential impact of the local surrounding environment on human health. Background: Researchers in Denmark have unique opportunities for conducting large population-ba...

Road transport is one of the significant sources of ambient air pollution. Machine learning approaches are becoming increasingly popular to predict and forecast air quality. In conjunction, this study aims to explore the potential of commonly used machine learning algorithms, Artificial Neural Networks (ANN), Random Forests (RF), and Support Vector...

Air pollution exhibits hyper-local variation, especially near emissions sources. In addition to people's time-activity patterns, this variation is the most critical element determining exposure. Pollution exposure is time-activity- and path-dependent, with specific behaviours such as mode of commuting and time spent near a roadway or in a park play...

The Copenhagen Metro comprises four lines, the M1, M2, M3 and M4, with 25 subterranean stations and an additional 14 stations above ground, serving ca. 80 million passengers annually. In this study we measure fine particulate matter (PM2.5) and carbon dioxide (CO2) concentrations in stations and in trains across the entire system. In partially unde...

In this study fine particulate matter (PM2.5) levels throughout the Copenhagen metro system are measured for the first time and found to be ∼10 times the roadside levels in Copenhagen. In this Part 2 article, low-cost sensor (LCS) nodes designed for personal-exposure monitoring are tested against a conventional mid-range device (TSI DustTrak), and...

Background: Established risk factors for breast cancer include genetic disposition, reproductive factors, hormone therapy, and lifestyle-related factors such as alcohol consumption, physical inactivity, smoking, and obesity. More recently a role of environmental exposures, including air pollution, has also been suggested. The aim of this study, wa...

Hyperlocal air quality maps are becoming increasingly common, as they provide useful insights into the spatial variation and sources of air pollutants. In this study, we produced several high-resolution concentration maps to assess the spatial differences of three traffic-related pollutants, Nitrogen dioxide (NO2), Black Carbon (BC) and Ultrafine P...

Accurate calibration of low-cost gas sensors is, at present, a time consuming and difficult process. Laboratory calibration and field calibration methods are currently used, but laboratory calibration is generally discounted due to poor transferability, and field methods requiring several weeks are standard. The Enhanced Ambient Sensing Environment...

Background: Particulate matter (PM) is classified as a group 1 human carcinogen. Previous experimental studies suggest that particles in diesel exhaust induce oxidative stress, inflammation and DNA damage in kidney cells, but the evidence from population studies linking air pollution to kidney cancer is limited. Methods: We pooled six European coho...

We assessed mortality risks associated with source-specific fine particles (PM2.5) in a pooled European cohort of 323,782 participants. Cox proportional hazard models were applied to estimate mortality hazard ratios (HRs) for source-specific PM2.5 identified through a source apportionment analysis. Exposure to 2010 annual average concentrations of...

Air pollution exhibits hyper-local variation, especially near emissions sources. In addition to people's time-activity patterns, this variation is the most critical element determining exposure. Pollution exposure is time-activity and path-dependent with specific behaviors such as mode of commuting and time spent near a roadway or in a park playing...

Background The majority of studies has shown higher greenness exposure associated with reduced mortality risks, but few controlled for spatially correlated air pollution and traffic noise exposures. We aim to address this research gap in the ELAPSE pooled cohort. Methods Mean Normalized Difference Vegetation Index (NDVI) in a 300-m grid cell and 1...

High-resolution air quality (AQ) maps based on street-by-street measurements have become possible through large-scale mobile measurement campaigns. Such campaigns have produced data-only maps and have been used to produce empirical models [i.e., land use regression (LUR) models]. Assuming that all road segments are measured, we developed a mixed mo...

Rationale: Ambient air pollution exposure has been linked to mortality from chronic cardiorespiratory diseases, while evidence on respiratory infections remains more limited. Objectives: We examined the association between long-term exposure to air pollution and pneumonia related mortality in adults in a pool of eight European cohorts. Methods:...

Background: The evidence linking ambient air pollution to bladder cancer is limited and mixed. Methods: We assessed the associations of bladder cancer incidence with residential exposure to fine particles (PM2.5), nitrogen dioxide (NO2), black carbon (BC), warm season ozone (O3) and eight PM2.5 elemental components (copper, iron, potassium, nick...

Background Many studies investigated the relationship between outdoor fine particulate matter (PM2.5) and cancer. While they generally indicated positive associations, results have not been fully consistent, possibly because of the diversity of methods used to assess exposure. Objectives To investigate how using different PM2.5 exposure assessment...

Background Long-term road traffic noise exposure is linked to cardio-metabolic disease morbidity, whereas evidence on mortality remains limited. Objectives We investigated association of long-term exposure to road traffic noise with all-cause and cause-specific mortality. Methods We linked 22,858 females from the Danish Nurse Cohort (DNC), recrui...

Background Long-term exposure to ambient air pollution has been associated with premature mortality, but associations at concentrations lower than current annual limit values are uncertain. We analysed associations between low-level air pollution and mortality within the multicentre study Effects of Low-Level Air Pollution: A Study in Europe (ELAPS...

Background Animal and epidemiologic studies indicate that air pollution may adversely affect fertility. Epidemiologic studies have been restricted largely to couples undergoing fertility treatment or have retrospectively ascertained time-to-pregnancy among pregnant women. Objectives We examined the association between residential ambient air pollu...

Background: Road traffic noise has been linked to increased risk of ischemic heart disease, yet evidence on stroke shows mixed results. We examine the association between long-term exposure to road traffic noise and incidence of stroke, overall and by subtype (ischemic or hemorrhagic), after adjustment for air pollution. Methods: Twenty-five tho...

Natural environments have been associated with mental health benefits, but globally access to these benefits is threatened by urban development and densification. However, it remains unclear how natural environments relate to mental health and how consistent the association is across populations. Here we use a life-course approach with a population...

Exposure to high levels of road traffic noise is associated with adverse health outcomes. Whereas cyclists' exposure to noise could substantially vary according to their route choice, the literature suggests that cyclists, in general, are exposed to higher noise levels than other transport mediums, e.g. cars. This work, therefore, aims to assess cy...

Objectives: Allergic diseases are prevalent in the working population, and work-related airborne pollen exposure might be substantial, especially among outdoor workers, resulting in work-exacerbated effects. Seasonal exposure to pollen may induce a priming effect on the allergic bronchial response resulting in exaggerated effects at the end of the...

Road transport is one of the significant sources of ambient air pollution. Machine learning approaches are becoming increasingly popular to predict and forecast air quality. In conjunction, this study aims to explore the potential of commonly used machine learning algorithms, Artificial Neural Networks (ANN), Random Forests (RF), and Support Vector...

Background We examined the association of long‐term exposure to air pollution and road traffic noise with incident heart failure (HF). Methods And Results Using data on female nurses from the Danish Nurse Cohort (aged >44 years), we investigated associations between 3‐year mean exposures to air pollution and road traffic noise and incident HF usin...

Background Long-term exposure to outdoor air pollution increases the risk of cardiovascular disease, but evidence is unclear on the health effects of exposure to pollutant concentrations lower than current EU and US standards and WHO guideline limits. Within the multicentre study Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE), we in...

Objective To investigate the associations between air pollution and mortality, focusing on associations below current European Union, United States, and World Health Organization standards and guidelines. Design Pooled analysis of eight cohorts. Setting Multicentre project Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) in six Euro...

Introduction: Epidemiological cohort studies have consistently found associations between long-term exposure to outdoor air pollution and a range of morbidity and mortality endpoints. Recent evaluations by the World Health Organization and the Global Burden of Disease study have suggested that these associations may be nonlinear and may persist at...

Particulate matter air pollution and diesel engine exhaust have been classified as carcinogenic for lung cancer, yet few studies have explored associations with liver cancer. We used six European adult cohorts which were recruited between 1985 and 2005, pooled within the “Effects of low‐level air pollution: A study in Europe” (ELAPSE) project, and...

BACKGROUND: Associations between long-term exposure to air pollution and road traffic noise have been established for ischemic heart disease, but findings have been mixed for atrial fibrillation (AF). OBJECTIVES: The goal of the study was to examine associations of long-term exposure to road traffic noise and air pollution with AF. METHODS: Time-...

Background Ambient air pollution is likely a risk factor for asthma, and recent evidence suggests the possible relevance of road traffic noise. Objectives We examined the associations of long-term exposure to air pollution and road traffic noise with adult-asthma incidence. Methods We followed 28,731 female nurses (age > 44 years) from the Danish...

This work reflects the recent and ongoing experiments to study individuals' time-activity patterns. The experiments are being conducted to develop a dynamic activity-based modelling framework to estimate subjects' activity-based personal exposure to air pollution. The first experiment was based on a walking activity towards Copenhagen lakes and bac...

Background Long-term exposure to ambient air pollution has been linked to childhood-onset asthma, although evidence is still insufficient. Within the multicentre project Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE), we examined the associations of long-term exposures to particulate matter with a diameter <2.5 µm (PM 2.5 ), nitroge...

Ultrafine particles (UFP; particulate matter <0.1 μm diameter) emitted from motorized traffic may be highly detrimental to health. Active mobility (walking, bicycling) is increasingly encouraged as a way to reduce traffic congestion and increase physical activity levels. However, it has raised concerns of increased exposure to UFP, due to increased...

NOx is a pervasive pollutant in urban environments. This review assesses the current state of the art of photocatalytic oxidation materials, designed for the abatement of nitrogen oxides (NOx) in the urban environment, and typically, but not exclusively based on titanium dioxide (TiO2). Field trials with existing commercial materials, such as paint...

Background While air pollution has been linked to the development of chronic obstructive pulmonary disease (COPD), evidence on the role of environmental noise is just emerging. We examined the associations of long-term exposure to air pollution and road traffic noise with COPD incidence. Methods We defined COPD incidence for 24 538 female nurses f...

Background: Evidence of nonauditory health effects of road traffic noise exposure is growing. This prospective cohort study aimed to estimate the association between long-term exposure to road traffic noise above a threshold and incident myocardial infarction (MI) in Denmark. Methods: In the Danish Nurse Cohort study, we used data of 22,378 wome...

This chapter explores how the Internet of Things and the utilization of cutting-edge information technology are shaping global research and discourse on the health and wellbeing of urban populations. The chapter begins with a review of smart cities and health and then delves into the types of data available to researchers. The chapter then discusse...

Background: Inconsistent associations between long-term exposure to particles with an aerodynamic diameter ≤2.5 μm [fine particulate matter (PM2.5)] components and mortality have been reported, partly related to challenges in exposure assessment. Objectives: We investigated the associations between long-term exposure to PM2.5 elemental component...

Background: Black carbon (BC), a component of fine particulate matter [particles with an aerodynamic diameter ≤2.5 μm (PM2.5)], may contribute to carcinogenic effects of air pollution. Until recently however, there has been little evidence to evaluate this hypothesis. Objective: This study aimed to estimate the associations between long-term expos...

Background An association between long-term exposure to fine particulate matter (PM2.5) and lung cancer has been established in previous studies. PM2.5 is a complex mixture of chemical components from various sources and little is known about whether certain components contribute specifically to the associated lung cancer risk. The present study bu...

The first-time in-depth comparison of the Nordic and European noise prediction standards.

Background We evaluated methods for the analysis of multi-level survival data using a pooled dataset of 14 cohorts participating in the ELAPSE project investigating associations between residential exposure to low levels of air pollution (PM2.5 and NO2) and health (natural-cause mortality and cerebrovascular, coronary and lung cancer incidence). M...

Objectives: To investigate if air pollution and greenness exposure from birth till adulthood affects adult asthma, rhinitis and lung function. Methods: We analysed data from 3428 participants (mean age 28) in the RHINESSA study in Norway and Sweden. Individual mean annual residential exposures to nitrogen dioxide (NO2), particulate matter (PM10...

Background/aim Ambient air pollution has been associated with lung cancer, but the shape of the exposure-response function - especially at low exposure levels - is not well described. The aim of this study was to address the relationship between long-term low-level air pollution exposure and lung cancer incidence. Methods The “Effects of Low-level...

Background Air pollution has been suggested as a risk factor for chronic obstructive pulmonary disease (COPD), but evidence is sparse and inconsistent. Objectives We examined the association between long-term exposure to low-level air pollution and COPD incidence. Methods Within the ‘Effects of Low-Level Air Pollution: A Study in Europe’ (ELAPSE)...

This volume of the Encyclopedia of Sustainability Science and Technology, Second Edition, provides a broad and comprehensive view of air pollution, extending from ground-level, localized air quality and regional and global air quality and effects, to sensors and measurement and air pollution control. Despite substantial improvements in many parts o...

Background Knowledge of the role of melatonin, xenograft experiments, and epidemiological studies suggests that exposure to light at night (LAN) may disturb circadian rhythms, possibly increasing the risk of developing breast cancer. Objectives We examined the association between residential outdoor LAN and the incidence of breast cancer: overall...

Background: Long-term exposure to ambient air pollution has been linked to childhood-onset asthma, while evidence is still insufficient. Within the multicentre project "Effects of Low-Level Air Pollution: A Study in Europe" (ELAPSE), we examined the associations of long-term exposures to particulate matter with diameter<2.5 µm (PM2.5), nitrogen di...

We developed Europe-wide models of long-term exposure to eight elements (copper, iron, potassium, nickel, sulfur, silicon, vanadium, and zinc) in particulate matter with diameter <2.5 μm (PM 2.5) using standardized measurements for one-year periods between October 2008 and April 2011 in 19 study areas across Europe, with supervised linear regressio...

The aim of this chapter is to present the Danish Nitrogen Mitigation Assessment (www.DNMARK.org), an ongoing five-year multidisciplinary research alliance, focusing on the quantification of nitrogen (N) flows and solutions scenarios for a more sustainable N use in Denmark. As one of the world’s most agriculturally intensive countries, with a long N...

Background The association between air pollution and mortality is well established, yet some uncertainties remain: there are few studies that account for road traffic noise exposure or that consider in detail the shape of the exposure–response function for cause-specific mortality outcomes, especially at low-levels of exposure. Objectives We exami...

We investigated if greenness and air pollution exposure in parents’ childhood affect offspring asthma and hay fever, and if effects were mediated through parental asthma, pregnancy greenness/pollution exposure, and offspring exposure. We analysed 1106 parents with 1949 offspring (mean age 35 and 6) from the Respiratory Health in Northern Europe, Sp...

In this pilot study, low-cost air pollution sensor nodes were fitted in waste removal trucks, hospital vans and taxis to record drivers’ exposure to air pollution in Central London. Particulate matter (PM 2.5 and PM 10 ), CO 2 , NO 2 , temperature and humidity were recorded in real-time with nodes containing low-cost sensors, an electrochemical gas...

Ambient air pollution has been linked to stroke, but few studies have examined in detail stroke subtypes and confounding by road traffic noise, which was recently associated with stroke. Here we examined the association between long-term exposure to air pollution and incidence of stroke (overall, ischemic, hemorrhagic), adjusting for road traffic n...

Cladosporium spp. and Alternaria spp. spores are dominating the airspora of Denmark. Currently, little is known about the influence of climate change on the fungal spore abundance in the air. The aim of this study was to examine temporal changes in airborne Alternaria and Cladosporium spores over 26 years. This is the first report of long-term airb...

Natural environments have been associated with mental health benefits worldwide. However, how different elements and types of natural environments associate with mental health is still largely unknown. In this study, we perform a detailed analysis on a large, nation-wide data set of mental health records (908 553 individuals) for Denmark combined w...

Childhood exposure to green space has previously been associated with lower risk of developing schizophrenia later in life. It is unclear whether this association is mediated by genetic liability or whether the 2 risk factors work additively. Here, we investigate possible gene-environment associations with the hazard ratio (HR) of schizophrenia by...

Background: Air pollution exposure has been linked to coronary heart disease, although evidence on PM 2.5 and myocardial infarction (MI) incidence is mixed. Objectives: This prospective cohort study aimed to investigate associations between long-term exposure to air pollution and MI incidence, adjusting for road traffic noise. Methods: We...

Air pollution and noise originating from urban road traffic have been linked to the adverse health effects e.g. cardiovascular disease (CVD), although their generation and propagation mechanisms vary. We aimed to (i) develop a tool to model exposures to air pollution and noise using harmonized inputs based on similar geographical structure (ii) exp...