*3.2. Survey Area*

The survey was conducted in Shanghai, Shenyang, and Chengdu, which are representative cities of the eastern region, northern region, and western region of China, respectively (Figure 2). In 2017, the permanent registered population was 14.55 million in Shanghai, 7.4 million in Shenyang, and 14.35 million in Chengdu. The annual GDP was 3063.3 billion yuan in Shanghai, 586.5 billion yuan in Shenyang, and 1388.9 billion yuan in Chengdu in 2017 [27].

**Figure 2.** Location map of Shanghai, Shenyang, and Chengdu. Source: Ministry of Natural Resources of the People's Republic of China (PRC).

Generally, these three cities categorize household garbage into four types: recyclable, hazardous, biodegradable (specifically known as 'wet waste' in Shanghai), and other waste (categorically called 'dry waste' in Shanghai). Both Shanghai and Chengdu stipulate local rewards for residents' sorting behaviors. Shanghai was selected in June 2000 for the implementation of China's first nationwide pilot program for garbage separation and collection, along with Beijing, Nanjing, Hangzhou, Guilin, Guangzhou, Shenzhen, and Xiamen. As past experience reveals, a high monitoring cost makes it hard for the governmen<sup>t</sup> to constantly detect the separation of solid waste from each household. It is therefore necessary to introduce some kind of incentive to induce social conscience for sustainable waste disposal behavior and practices.

In 2014, the Shanghai Huizhong Green Corporate Social Responsibility was established, with the aim to encourage citizens to sort kitchen garbage and other waste based on an economic incentive system, called the Green Account program. Under this system, one Green Account card is issued to one household upon request. If the household discards sorted kitchen garbage during the designated hours (7:00 to 9:00 in the morning, and 17:00 to 19:00 in the evening), it receives ten points each time (up to a maximum of 20 points per day). The points received are valid for two years, and can be exchanged for everyday items, movie tickets, or park tickets, among other things [28,29].

In Chengdu, Sichuan Province, the Chengdu Green Earth Environment Technology Co., a pioneer in the waste classification field in China, introduced the Green Earth program in 2008, with the aim to encourage residents to sort recyclable waste. Green Earth provides each family with a unique barcode sticker that can be put on the trash bag for identification. Households can receive reward points based on the weight of the trash bags placed in the designated recycling bins. For example, every 100 g of normal recyclable garbage (paper, plastic, and metal), every 200 g of glass, or every 500 g of clothes

will receive one green point. The points received are valid for two years, and can be exchanged for detergents, toothpastes, and other everyday items [30].
