Influence of tourism on the local air quality in the Mountain Laoshan forest scenic areas

Tourism activities can have a significant impact on air quality in forest scenic areas. In this work, we measured the levels of volatile organic compounds (VOCs), including carbonyls and non-methane hydrocarbons (NMHCs), in the national forest park of Mountain Laoshan (Mt. Laoshan) in Qingdao, China, and evaluated the impact of these levels on air quality in this specific area. We found that during the May Day holidays (May 1–5, 2021), when the number of tourists is typically high, the average of VOCs total concentration was around 23.8 ± 22.6 ppbv, about 1.5 times higher than during periods with fewer tourists, ≈16.3 ± 15.2 ppbv. Most VOC species exhibited a bimodal profile diurnal variation during lunch and dinner periods. Using the Positive Matrix Factorization (PMF) model, five anthropogenic sources were identified, with liquefied petroleum gas (LPG) usage and traffic emissions being the two primary sources of VOCs in the Mt. Laoshan forest scenic area, respectively. The results indicate that tourism has a significant impact on atmospheric VOCs levels in the investigated area. Based on a 0-D model, we studied the effects of additional emissions from human activity on the atmospheric chemistry in the Mt. Laoshan forest scenic area. It was found that the additional NOx and VOCs emissions from tourism obviously increased the NO₃ reactivity during the night and OH formation during the daytime, which significantly increases the local atmospheric oxidation capacity. Therefore, this study emphasizes the significant impact of tourism activities, such as catering and traffic emissions, on the local air quality in forest scenic areas.