Secondhand smoke exposure in public outdoor spaces in the Netherlands: The stronger the smell, the more exposure to nicotine.

INTRODUCTION: While secondhand smoke exposure in outdoor spaces has been investigated before, no data on outdoor secondhand smoke exposure have been collected in the Netherlands. Such data could help policymakers gain support for smoke-free outdoor public spaces. METHODS: Between May and November 2021, we visited 25 outdoor locations across the Netherlands. At each location, we conducted four measurements with smokers and one measurement without smokers. During each measurement, we counted the number of smokers present and we rated tobacco smell intensity on a five-point scale. Airborne nicotine and 3-ethenylpyridine (3-EP) data were collected through active sampling on thermal desorption tubes. The contents of these tubes were later analyzed using gas chromatography-mass spectrometry. Using linear mixed models, we investigated the association between levels of nicotine and the presence of smokers, the number of smokers, and the intensity of tobacco smell. We also investigated these association with levels of 3-EP. RESULTS: Nicotine levels were higher when smokers were present (B=1.40; 95% CI: 0.69-2.11, p<0.001). For each additional smoker present, we measured higher levels of nicotine (B=0.23; 95% CI: 0.10-0.37, p=0.001). When the smell of tobacco smoke was noted to be stronger by the researchers, higher levels of nicotine were measured through sampling (B=0.85; 95% CI: 0.44-1.26, p<0.001). We found similar results for 3-EP levels. CONCLUSIONS: This study showed that both nicotine and 3-EP are useful in quantifying levels of secondhand smoke in various outdoor locations. The level of nicotine exposure outdoors was positively associated with the number of smokers nearby. The intensity of the tobacco smell was also related to nicotine exposure: the stronger the smell of tobacco smoke, the more nicotine was measured in the air.

Estimating and Testing Causal Mediation Effects in Single-Case Experimental Designs Using State-Space Modeling.

In this article, we present single-case causal mediation analysis as the application of causal mediation analysis to data collected within a single-case experiment. This method combines the focus on the individual with the focus on mechanisms of change, rendering it a promising approach for both mediation and single-case researchers. For this purpose, we propose a new method based on time-discrete state-space modeling to estimate the direct and indirect treatment effects. We demonstrate how to estimate the model for a single-case experiment on stress and craving in a routine alcohol consumer before and after an imposed period of abstinence. Furthermore, we present a simulation study that examines the estimation and testing of the standardized indirect effect. All parameters used to generate the data were recovered with acceptable precision. We use maximum likelihood and permutation procedures to calculate p-values and standard errors of the parameters estimates. The new method is promising for testing mediated effects in single-case experimental designs. We further discuss limitations of the new method with respect to causal inference, as well as more technical concerns, such as the choice of the time lags between the measurements.

Testing Mediators of Youth Intervention Outcomes Using Single-Case Experimental Designs.

The major aim of this manuscript is to bring together two important topics that have recently received much attention in child and adolescent research, albeit separately from each other: single-case experimental designs and statistical mediation analysis. Single-case experimental designs (SCEDs) are increasingly recognized as a valuable alternative for Randomized Controlled Trials (RCTs) to test intervention effects in youth populations. Statistical mediation analysis helps provide understanding about the most potent mechanisms of change underlying youth intervention outcomes. In this manuscript we: (i) describe the conceptual framework and outline desiderata for methods for mediation analysis in SCEDs; (ii) describe the main aspects of several data-analytic techniques potentially useful to test mediation in SCEDs; (iii) apply these methods to a single-case treatment data set from one clinically anxious client; and (iv) discuss pros and cons of these methods for testing mediation in SCEDs, and provide future directions.