In recent years, Thailand has faced a number of environmental issues, such as air pollution, water pollution, soil pollution and noise pollution (Panya, Poboon, Phoochinda, & Teungfung, 2018) Especially in the past 2 years, Thailand has experienced severe air pollution, causing the PM 2.5 level to exceed the standard level. It then affects people's living style so they have more concerns about environment changing behavior and wish to focus more and more on green consumption (Thongplew, Spaargaren, & van Koppen, 2017). Companies and brands have been developing their products to be more environmentally friendly to gain a competitive advantage. However, companies are still facing unpredictable customers' minds and decision-making (Gen, Juan, & Xixiang, 2019) caused by the price sensitivity of customers and other factors. Nevertheless, previous research has found that customers the green products when they trust the brand (Liobikienė et al., 2017; Tseng & Hung, 2013; Wu, Lin, & Chen, 2017). Although there is various research on trust affecting green product buying behaviors, there is little research focusing on brand trust, leading to brand engagement and loyalty to green products. That could contribute to our understanding of brand strategies in green product markets.

Keywords: Brand engagement, Brand trust, Green product, Loyalty