Photochemical processes drive much of the daytime gas-phase chemistry in the atmosphere. Within condensed phases, such as aerosol particles and thin films enriched in organics, much less is understood about these processes. An investigation aimed at better understanding photosensitized reactions that can occur within marine-relevant condensed-phase systems is described herein. In particular, photosensitized reactions have been investigated between a fatty acid model system and different photosensitizers within thin organic films representative of molecular species found in the sea surface microlayer and sea spray aerosols. Photosensitized reactions of thin films containing nonanoic acid and three different photosensitizers, including 4-benzoylbenzoic acid, humic acid, and marine-derived dissolved organic matter, were probed using a suite of analytical techniques, including vibrational spectroscopy, excitation–emission matrix spectroscopy, and ultra-high-resolution mass spectrometry. Considerable differences were found in the photosensitizing capability for each of these systems. We also present an analysis of the molecular differences between the different photosensitizers to explain their unique characteristics and light-absorbing properties. Overall, this study sheds light on the relevance of such reactions in the marine environment.

Background Physical activity (PA) literature is dominated by individual-level descriptive studies, which are known to have limited impact on population PA levels. Leveraging systems science methods offers opportunities to approach PA in a manner which embraces its inherent complexity. This study describes how participatory systems mapping and social network analysis (SNA) were used to understand the work of local and national level walking systems in Ireland. Methods Two adapted participatory action research workshops with multisectoral stakeholders were used to develop a systems map for walking in Cork, Ireland. The Global Action Plan for Physical Activity 2018–2030 (GAPPA) map was used as a framework to categorize workshop outcomes. Secondly, SNA methods were used to analyse the communication network between partners of Get Ireland Walking, a national walking promotion initiative, as defined within their strategic plan and the actual communication network as experienced by the partners. Results The systems mapping process allowed stakeholders to identify 19 suggested actions for the Cork walking system. The SNA found that there were considerably fewer communication ties between partners in the actual communication network than in the strategy defined network. Conclusion The systems mapping process was a useful catalyst for engaging stakeholders in cross-sectoral communication and the GAPPA was a practical way to organize workshop outcomes. Social network analysis methods highlighted that the communication network of a national level walking promotion partnership is not working as planned. Overall, the use of systems science methods can provide practical insights for local and national level walking systems.

IntroductionIncreasing population levels of walking holds benefits for public and planetary health. While individual level interventions to promote walking have been shown to be efficacious, upstream interventions such as policies harness the greatest potential for impact at the population level. However, little is known about the nature and presence of walking policy in Ireland and the extent to which it aligns to national and global goals. This paper aims to provide an overview of local and national walking policy in Ireland and to understand the potential of Irish walking policy to contribute to national and global targets.MethodsThis study used multiple methods to provide a critical overview of walking policy. Firstly, a six-phase process was employed to conduct a content analysis of local and national walking policy in Ireland. Secondly, conceptual linkage exercises were conducted to assess the contribution of walking, and national walking policy in Ireland, to Ireland's National Strategic Outcomes and the United Nations Sustainable Development Goals.ResultsOverall, half (n = 13) of the counties in the Republic of Ireland were found to have no local level walking policies. Results from the content analysis suggest that counties which had walking specific local level policies (n = 2) were outdated by almost two decades. Walking was identified to hold the potential to contribute to over half (n = 6) of Ireland's National Strategic Outcomes, and over half (n = 7) of the United Nations Sustainable Development Goals. Ireland's only national level walking specific policy, the Get Ireland Walking Strategy and Action Plan 2017–2020, was identified to potentially contribute to four of Ireland's National Strategic Outcomes and three United Nations Sustainable Development Goals.DiscussionMultidisciplinary action is required to update walking-related policy with embedded evaluation and governance mechanisms in all local walking systems. Furthermore, given sufficient collaboration across sectors, walking policy in Ireland has the potential to contribute to a wider breadth of national and global targets beyond the health, sport, tourism, and transport sectors.

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Background Organisations operating at multiple levels of the physical activity and outdoor recreation ecosystem in Ireland collect data pertaining to recreational trail use, yet despite its potential utility, there is no centralised surveillance system for Irish walking trails. Due to the little effort to collate data, recreational walking trail usage in Ireland during the COVID-19 pandemic is unknown. The aims of this study are twofold. Firstly, this study aims to compare trends in footfall count data on Irish trails prior to, and during, the period following the outbreak of COVID-19. Secondly, this study aims to triangulate findings from footfall count data with openly available mobility data. Methods This descriptive study analysed changes in footfall counts gathered from passive infrared sensors on 33 of Ireland's walking trails between January 2019 and December 2020. The relationship between Google Community Mobility Report (GCMR) data and footfall counts was analysed to corroborate trends in footfall data. Results Overall, total footfall increased by 6% (p = 0.024) between 2019 and 2020 on trails included in this analysis. Notably, mean trail usage was between 26% and 47% higher (p = 0.002) in October-December 2020 than during the same period in 2019. On average, trails >2km from an urban area had higher footfall during all periods of movement restrictions. Conclusions The conclusions of this study are twofold. Firstly, recreational walking trail use increased during the COVID-19 pandemic, especially on trails closer to urban areas. The increase reported here poses questions relating to the potential positive legacy which the pandemic period may have had on recreational trail use. Secondly, combining multiple data sources can provide trail managers with more detailed representations of trail usage. However, there are currently little efforts to harmonise data. Future research should examine the multi-level determinants of trail use to inform context specific trail promotion campaigns. Furthermore, investigating novel ways to coordinate heterogeneous datasets pertaining to recreational walking may prove fruitful for the fields of outdoor recreation and physical activity research.