Michelle Laeremans

Physical Activity through Sustainable Transport Approaches (PASTA): a study protocol for a multicentre project

Introduction Only one-third of the European population meets the minimum recommended levels of physical activity (PA). Physical inactivity is a major risk factor for non-communicable diseases. Walking and cycling for transport (active mobility, AM) are well suited to provide regular PA. The European research project Physical Activity through Sustainable Transport Approaches (PASTA) pursues the following aims: (1) to investigate correlates and interrelations of AM, PA, air pollution and crash risk; (2) to evaluate the effectiveness of selected interventions to promote AM; (3) to improve health impact assessment (HIA) of AM; (4) to foster the exchange between the disciplines of public health and transport planning, and between research and practice. Methods and analysis PASTA pursues a mixed-method and multilevel approach that is consistently applied in seven case study cities. Determinants of AM and the evaluation of measures to increase AM are investigated through a large scale longitudinal survey, with overall 14 000 respondents participating in Antwerp, Barcelona, London, Örebro, Rome, Vienna and Zurich. Contextual factors are systematically gathered in each city. PASTA generates empirical findings to improve HIA for AM, for example, with estimates of crash risks, factors on AM-PA substitution and carbon emissions savings from mode shifts. Findings from PASTA will inform WHOs online Health Economic Assessment Tool on the health benefits from cycling and/or walking. The studys wide scope, the combination of qualitative and quantitative methods and health and transport methods, the innovative survey design, the general and city-specific analyses, and the transdisciplinary composition of the consortium and the wider network of partners promise highly relevant insights for research and practice. Ethics and dissemination Ethics approval has been obtained by the local ethics committees in the countries where the work is being conducted, and sent to the European Commission before the start of the survey. The PASTA website (http://www.pastaproject.eu) is at the core of all communication and dissemination activities.

Wearable Sensors for Personal Monitoring and Estimation of Inhaled Traffic-Related Air Pollution: Evaluation of Methods

Physical activity and ventilation rates have an effect on an individuals dose and may be important to consider in exposure-response relationships; however, these factors are often ignored in environmental epidemiology studies. The aim of this study was to evaluate methods of estimating the inhaled dose of air pollution and understand variability in the absence of a true gold standard metric. Five types of methods were identified: (1) methods using (physical) activity types, (2) methods based on energy expenditure, METs (metabolic equivalents of task), and oxygen consumption, (3) methods based on heart rate or (4) breathing rate, and (5) methods that combine heart and breathing rate. Methods were compared using a real-life data set of 122 adults who wore devices to track movement, black carbon air pollution, and physiological health markers for 3 weeks in three European cities. Different methods for estimating minute ventilation performed well in relative terms with high correlations among different methods, but in absolute terms, ignoring increased ventilation during day-to-day activities could lead to an underestimation of the daily dose by a factor of 0.08-1.78. There is no single best method, and a multitude of methods are currently being used to approximate the dose. The choice of a suitable method for determining the dose in future studies will depend on both the size and the objectives of the study.

Physical activity and sedentary behaviour in daily life: A comparative analysis of the Global Physical Activity Questionnaire (GPAQ) and the SenseWear armband

Reduction of sedentary time and an increase in physical activity offer potential to improve public health. However, quantifying physical activity behaviour under real world conditions is a major challenge and no standard of good practice is available. Our aim was to compare the results of physical activity and sedentary behaviour obtained with a self-reported instrument (Global Physical Activity Questionnaire (GPAQ)) and a wearable sensor (SenseWear) in a repeated measures study design. Healthy adults (41 in Antwerp, 41 in Barcelona and 40 in London) wore the SenseWear armband for seven consecutive days and completed the GPAQ on the final day. This was repeated three times. We used the Wilcoxon signed rank sum test, Spearman correlation coefficients, mixed effects regression models and Bland-Altman plots to study agreement between both methods. Mixed models were used to assess the effect of personal characteristics on the absolute and relative difference between estimates obtained with the GPAQ and SenseWear. Moderate to vigorous energy expenditure and duration derived from the GPAQ were significantly lower (p<0.05) compared to the SenseWear, yet these variables showed significant correlations ranging from 0.45 to 0.64. Estimates of vigorous-intensity physical activity in particular showed high similarity (r>0.59). Results for sedentary behaviour did not differ, yet were poorly correlated (r<0.25). The differences between all variables were reproducible across repeated measurements. In addition, we observed a relationship between these differences and BMI, body fat and physical activity domain. Due to the lack of a standardized protocol, results from different studies measuring physical activity and sedentary behaviour are difficult to compare. Therefore, we suggested an easy-to-implement approach for future studies adding the GPAQ to the wearable of choice as a basis for comparisons.

Short-term effects of physical activity, air pollution and their interaction on the cardiovascular and respiratory system

Physical activity (PA) in urban environments may lead to increased inhalation of air pollutants. As PA and air pollution (AP) have respectively beneficial and detrimental effects on the cardiorespiratory system, the responses to these exposures can interact. Therefore, we assessed the short-term effects of PA, AP and their interaction on a set of subclinical cardiovascular and respiratory outcomes in a panel of healthy adults: heart rate variability (HRV), retinal vessel diameters, lung function and fractional exhaled nitric oxide (FeNO). One hundred twenty two participants measured their PA level and exposure to black carbon (BC), a marker of AP exposure, with wearable sensors during an unscripted week in three different seasons. The study was part of the PASTA project in three European cities (Antwerp: 41 participants, Barcelona: 41 participants, London: 40 participants). At the end of each measurement week, the health outcomes were evaluated. Responses to PA, BC and their interaction were assessed with mixed effect regression models. Separate models were used to account for a 2-h and 24-h time window. During the 2-h time window, HRV and lung function changed statistically significantly in response to PA (METhours) and logarithmic BC (%change). Changes in HRV marked an increased sympathetic tone with both PA (logarithmic LF/HF: +7%; p < 0.01) and BC (logarithmic HF: -19%; p < 0.05). In addition, PA provoked bronchodilation which was illustrated by a significant increase in lung function (FEV1: +15.63 mL; p < 0.05). While a BC %increase was associated with a significant lung function decrease (PEF: -0.10 mL; p < 0.05), the interaction indicated a potential protective effect of PA (p < 0.05). We did not observe a response of the retinal vessel diameters. Most subclinical outcomes did not change in the 24-h time window (except for a few minor changes in LF/HF, FeNO and PEF). Our results on the separate and combined effects of short-term PA and AP exposure on subclinical markers of the cardiorespiratory system are relevant for public health. We provide insights on the physiological responses of multiple, complementary markers. This may move further research towards elucidating potential pathways to disease and the long-term clinical impact of the observed physiological changes.

Concern over health effects of air pollution is associated to NO 2 in seven European cities

Subjective perception of air pollution is important and can have impacts on health in its own rights, can lead to protective behaviour, or it can be leveraged to engage citizens and stakeholders in support of cleaner air policies. The aim of the current analysis was to examine associations between level of concern over health effects of air pollution and personal and environmental factors. In seven European cities, 7622 adult participants were recruited to complete an online questionnaire on travel and physical activity behaviour, perceptions and attitudes on active mobility and the environment, and sociodemographics. Air pollution at the home address was determined using Europe-wide PM2.5 and NO2 land use regression models. Mixed effects logistic regression was used to model concern over air pollution (worried versus not worried; city as random effect). Fifty-eight percent of participants were worried over health effects of air pollution with large differences across cities (Antwerp 78%, Barcelona 81%, London 64%, Orebro 11%, Rome 72%, Vienna 43%, Zurich 33%). Linking mean modelled air pollution to mean level of concern per city gave a good correlation for NO2 (r2 = 0.75), and a lower correlation for PM2.5 (r2 = 0.49). In the regression model, sex, having children in the household, levels of physical activity, and NO2 at the home address were significantly linked to individual concern over health effects of air pollution. We found that NO2 but not PM2.5 at the home address was associated with concern over health effects of air pollution.

1 Transport modes and subjective general health: roles of mental health, social contacts, and physical activity

Background/aim Transport behaviours have been associated with several positive and negative health effects. The current study evaluates the association between different modes of transport and subjective general health in an adult population in seven European cities, and explores whether mental health, vitality, perceived stress, social contacts, and physical activity are mediators of this association. Methods A longitudinal study was performed in seven European cities (Antwerp, Barcelona, London, Örebro, Rome, Vienna, and Zürich). Participants responded to two comprehensive questionnaires (Baseline and Final) concerning their transport behaviour and health, using an on-line platform. The transport mode usage was assessed using a frequency scale (days/month) of five different transport modes: car, motorbike, public transport, e-bike, bicycle, and walking. Participants were categorised as with ‘good or more’ or ‘less than good’ subjective general health. Multilevel regression models will be used to evaluate the association between transport mode and subjective general health, adjusting for potential confounders. We will follow Vander Weele’s framework to establish the mediation roles. Results (ongoing analyses): The sample had more than 7000 adults, fairly distributed in the seven cities (16% Antwerp, 16% Barcelona, 14% London, 10% Örebro, 14% Rome, 16% Vienna, 14% Zürich). In initial analyses we find positive associations between active transport modes (e-bike, bicycle, walking) and subjective general health and negative associations between motorised transport modes (car, motorbike, public transport) and subjective general health. We also expect to find indications for mediation of these associations by mental health, vitality, perceived stress, social contacts, and physical activity. Conclusion We hypothesise that mental health, social contacts, perceived stress, and levels of physical activity may be important consequences of transport behaviours which could lead to different levels of subjective general health.

P I – 1–7 Effects of air pollution and physical activity on blood pressure

Background/aim The increased inhalation rate during physical activity in urban environments may result in increased inhaled dose of traffic-related air pollutants. Short-term exposure to traffic-related air pollutants has been associated with increasing blood pressure. The current study assesses the main effects and interaction effects of traffic-related air pollution and physical activity on blood pressure. Methods A panel study was performed in three European cities (Antwerp, Barcelona, and London) with 122 healthy adults (approx. 40 participants/city) who completed 7 day measurement periods in winter, summer, and mid-season, between February 2015 and March 2016. The participants wore sensors to measure exposure to black carbon (marker of traffic-related air pollution) and physical activity levels. Blood pressure was measured three times during each measurement period. Participants also completed a questionnaire about their personal characteristics and lifestyle behaviours. Multilevel regression models will be used to assess associations and interaction effects. All models will be adjusted by potential confounders. Results (ongoing analyses): Participants had a median (IQR) moderate-to-vigorous physical activity of 71 (49–111) min/day measured by an accelerometer. Mean black carbon exposure over all sample in coinciding time periods was 1636±673 ng/m³. The mean black carbon exposure increased with higher levels of physical activity. In initial analyses we find associations between the two exposures (black carbon and physical activity) and blood pressure. We also expect to find that physical activity levels moderates the negative effects of black carbon exposure on blood pressure. Conclusion We hypothesise that the cardiovascular effects from traffic-related air pollution exposure could be attenuated by physical activity levels.

P II – 2–7 No2 but not pm2.5 at the home address is associated with concern over health effects of air pollution

Background/aim People living in urban areas in Europe are exposed to elevated concentrations of air pollution. The lower the air pollution levels, the better for your health; so people exposed to higher concentrations should be worried more about air pollution. The aim of this analysis was to examine associations between concern over health effects of air pollution and personal and environmental factors. Methods In 7 European cities, >12 000 participants over 18 years were recruited to complete an online questionnaire on travel and physical activity behaviour, perceptions and attitudes, and sociodemographics. The following question was assessed on a 5-point scale: ‘Are you worried that air pollution in the neighbourhood of either your home or work can lead to health problems?’ Mixed effects logistic regression was used to model concern over health effects of air pollution (worried (level 4–5) versus not-worried (level 1–3); city as random effect). Air pollution at the home address was determined using the West-European PM2.5 and NO2 land use regression models from de Hoogh et al. (2016). Potential confounding variables were chosen based on previous studies, and most variables were self-reported. Results 57% of participants were worried over health effects of air pollution with large differences across cities (Antwerp 77%; Barcelona 81%; London 64%; Oerebro 12%; Rome 72%; Vienna 43%; Zurich 34%). Linking mean modelled air pollution to mean level of concern per city, gave a good correlation for NO2 (r²=0.75) and a lower correlation for PM2.5 (r²=0.49). In bivariate analyses, city, sex, education level, self-reported health, having children in the household, distance to the nearest major road, physical activity level, and NO2 and PM2.5 at home were significantly linked to concern over health effects of air pollution. In the mixed effects logistic regression model sex, self-reported health, having children in the household, physical activity level, and NO2 at home remained significant. Conclusion Being male, having a worse self-reported health, having children in the household, being more physically active, and higher NO2 at the home address were associated with higher concern over health effects of air pollution.

Transport mode choice and body mass index: Cross-sectional and longitudinal evidence from a European-wide study

BACKGROUND In the fight against rising overweight and obesity levels, and unhealthy urban environments, the renaissance of active mobility (cycling and walking as a transport mode) is encouraging. Transport mode has been shown to be associated to body mass index (BMI), yet there is limited longitudinal evidence demonstrating causality. We aimed to associate transport mode and BMI cross-sectionally, but also prospectively in the first ever European-wide longitudinal study on transport and health. METHODS Data were from the PASTA project that recruited adults in seven European cities (Antwerp, Barcelona, London, Oerebro, Rome, Vienna, Zurich) to complete a series of questionnaires on travel behavior, physical activity levels, and BMI. To assess the association between transport mode and BMI as well as change in BMI we performed crude and adjusted linear mixed-effects modeling for cross-sectional (n = 7380) and longitudinal (n = 2316) data, respectively. RESULTS Cross-sectionally, BMI was 0.027 kg/m2 (95%CI 0.015 to 0.040) higher per additional day of car use per month. Inversely, BMI was -0.010 kg/m2 (95%CI -0.020 to -0.0002) lower per additional day of cycling per month. Changes in BMI were smaller in the longitudinal within-person assessment, however still statistically significant. BMI decreased in occasional (less than once per week) and non-cyclists who increased cycling (-0.303 kg/m2, 95%CI -0.530 to -0.077), while frequent (at least once per week) cyclists who stopped cycling increased their BMI (0.417 kg/m2, 95%CI 0.033 to 0.802). CONCLUSIONS Our analyses showed that people lower their BMI when starting or increasing cycling, demonstrating the health benefits of active mobility.