Perceived Health Effects of Chinese Wetland Parks in the Context of COVID-19

Wetland parks are designed to support urban ecological protection, ood control and human well-being. Existing research mainly focuses on their inuence on ecology and economy. However, their inuence on human well-being and health is rarely studied. During the peak of the COVID-19 pandemic (Peak), people were very concerned about health, while simultaneously wetland parks which are generally considered benecial to health were shut down. Thus, this study explores the publics’ perception of the health effects of visiting wetland parks and the impact of the pandemic on the perception. From March 5th to 8th, 2020, before the Peak in China was over, 1,400 respondents were surveyed online nationwide. It was found that generally, the public perceived physical and mental health benets by visiting WPs, and perceived higher benets in mental health than in physical health. The expected (i.e. imagined) perceived health benets after the Peak were slightly higher than before the pandemic. The results highlight that wildlife habitat services were considered to be the most important ecosystem services that promote the perceived health benets. Interestingly, health experts perceived health benets to be lower from WPs than other groups, indicating that the health benets of visiting WPs may be overestimated by lay-people or underestimated by health experts. The results provide empirical evidence for managing ecosystem services as delivered by these urban wetlands, in the context of COVID-19 or potential future pandemics, for promoting public health. (Ni 2020), people's physical and mental health (see Sect. 1.2.2). A possible reason for the lowest perceived health benets during the Peak could be the higher risk of infection. Limited access to WPs during the Peak could also contribute to the low perception of health benets. The increase in perceived health benets after the Peak shows that inaccessibility to WPs for a period of time may improve perceived health benets from WPs. context of COVID-19 in China to contribute to existing knowledge of health benets of urban blue and green spaces and the link between ecosystem services and human health. This study conrms that most people can perceive the health benets of WPs. A slightly higher level of perceived health benets after the Peak than before indicates that limited access to WPs increases perceived health benets. Whilst very high epidemic risks might be said to have a negative impact on perceived physical health benets, and lower risks may not be conducive to perceived mental health benets, the moderate epidemic risk seems to be associated with greater physical and mental health benets for visiting WPs during the Peak. Also, quarantine did not lead to an increase in health-related motivation for visiting WPs. Interestingly, health experts perceived lower health benets than laypeople. At the same time, habitat services, which were regarded as indirect health-related ES, were perceived as the most crucial ES for promoting the perceived health benets in WPs. Overall, a better understanding of the perception of health benets of WPs in the context of COVID-19 can help to provide empirical evidence for managing ecosystem services as delivered by WPs, or green and blue space in general, in the context of COVID-19 or potential future pandemics.

The main aim of the research is to (1) understand the public's perception of the health effect of WPs before, during, and after the peak of the COVID-19 pandemic (Peak), and (2) understand the impact of the epidemic and other factors on people's perception of health effect of WPs.

Data Collection: Online Questionnaire
The data for the study was collected nationwide in China through online questionnaires, using the Tencent Questionnaire platform. The differences in pandemic risks across provinces were used to study the impact of the epidemic on perceived health effects. The questionnaire was distributed using snowball sampling on social media such as WeChat as the "seed", from March 5th to 8th, 2020. Once the target number of total valid responses (1,400) was reached, data collection was stopped. After collecting demographic data, questions of "whether you would like to visit a park/WPs after the pandemic is over?" were asked; the survey would continue if the respondents indicated willingness to visit WPs. Participants who were unwilling to visit were asked to give reasons.
Other independent variables (in uencing factors at four levels) and dependent variables (perceived health effects related to WPs) were collected, as described in the following sections. Respondents spent an average of 6.5 minutes lling out the questionnaire. Two rounds of pre-tests were conducted before March 5th to ensure that respondents correctly understand the questionnaire.

Dependent Variable: Perceived Health Effects Associated with WPS
This study uses perceived health bene ts or risks as dependent variables to characterize the impact of wetland parks on health perceived by citizens. A sevenpoint Likert Scale was used to evaluate the perceived mental and physical health effects of visiting WPs before, during, and after the Peak. Respondents were asked "Before/During/After the Peak, what do you think will be the impact of visiting WPs on your physical/mental health?" respectively.

Independent Variables: Factors of Perceived Health Effects
This study included four levels of variables, namely city, community, WPs, and individual levels.

City Level
During the Peak, the severity of the epidemic situation (i.e. the numbers of cumulative con rmed cases, newly con rmed cases and deaths) varied among provinces and cities in China, leading to different epidemic risks and emergency policies. These may affect the perceived health effects of wetland parks. The Response Level to Public Health Emergency (RLPHE) in a given region on a single day can re ect the risk level of an outbreak in that region on that day. The investigation period was at the end of the Peak, and some areas where the outbreak was not severe (i.e. there was not many con rmed cases and there had been no newly con rmed cases for a while) have lowered the RLPHE.
By asking about the main cities of residence at the peak of the epidemic, and according to the RLPHE of all provinces and cities across the country on March 6th (midpoint in the sampling period), these cities were classi ed into three categories: rst-level response, namely the highest risk; second-level response, high risk; third-level response, medium risk.

Community Level
During the Peak, many communities in cities with higher epidemic risk levels were locked down. Some communities were entirely locked down, and quarantine was required. Some communities were semi locked down, where residents could leave their homes and do activities in the communities, but could not go out of the community unless necessary. In low-risk cities, the communities were not closed. Information on the degree of community lockdown during the Peak was collected using a single-choice question.

Health Effects of WPs
Respondents were asked about the name of the wetland park they often visited or their favourite and why they like this WP. The wetland parks that the participants visited most or their favourites were classi ed according to the main wetland types they contain (e.g., lakes, rivers, coast, swamp), and the correlation analysis of various types of wetland parks in the same corresponding level of regions with health bene ts perception was carried out to study the perceived health effects of preferred wetland types.

Health Effects of Ecosystem Services
This study explored the perceived ESs from wetland parks and the health effect of these perceived ESs, by asking participants to make multiple choices for perceived ESs rst, and then ranking their choices according to importance to the improvement of their physical and mental health. ESs including habitat, water puri cation, air puri cation, noise reduction, ood regulation, recreation, aesthetics, education, and social relations were involved. These examined ESs were selected according to previous studies on perceived ESs in WPs (Zhai and Lange 2020). They belonged to the regulating, cultural and supporting category. The provisioning services were not examined in this study because WPs do not always deliver provisioning services (e.g. food, raw materials).

Individual Level
This part rst collected the respondents' socio-demographic details (such as age, gender, highest education level, professional, occupation status, and city of residence) through ve single-choice questions and two drop-down questions. Respondents' self-reported physical and mental health status before and during the Peak was then collected through four ve-point Likert scale questions.

Data Analysis
All statistical analyses were performed using SPSS Statistics 25. Descriptive statistics were used to analyze the respondents' pro les. The open-ended questions were coded for descriptive statistics. Analysis of variance (ANOVA) and one-way T-test were used to examine whether various factors affect perceived health effects. Bivariate correlation analysis was used to study the correlation between self-reported health status and perceived health effects. [1] When the survey was conducted, the epidemic was expected to end by April 2020. However, this epidemic subsequently developed into a global pandemic and has not yet ended. Therefore, in the questionnaire, "during the epidemic" refers to the Peak, and "after the epidemic" and "when the epidemic is over" mean "after the Peak".

Respondents' pro les
The majority of the respondents were young and middle-aged and enjoyed a high level of education (graduate or higher) ( Table 3). 57.9% of the respondents were females. 63.0% of the respondents were employed, 27.8% were students, and others were retired or unemployed. 43.2% were engaged in architecture and built environment, and 6.14% were health experts (i.e. medical and nursing or psychology professionals). Respondents came from 31 provinces and were evenly distributed in cities with the three levels of RLPHE. During the Peak, 75.3% of the respondents lived in semi-lockdown communities, 18.8% were quarantined at home, and 5.9% had free access to their homes and communities.

Willingness to Visit WPs
81.6% of the respondents were willing to visit parks after the Peak (N=1142). 76.9% of those who wanted to visit parks also wished to visit wetland parks (N=1077). The main reasons for not visiting WPs were poor accessibility (52.3%). After the Peak, 28.2% of the respondents would increase their visiting frequency, while 55.3% of respondents would keep their visiting frequency.
A total of 109 respondents had visited WPs (e.g. Figure 2) since they reopened after the peak of the epidemic within two weeks. Fresh air (57.8%), physical exercise (43.1%), and exposure to nature and wildlife habitats (42.2%) were the main motivations. 'WPs sparsely populated with low risk of infection' (36.7%), 'Basking in the sun and enjoy the breeze' (35.8%) and 'enjoy the beautiful scenery' (29.4%) were important driving factors.

Dependent Variables: Perceived Health Effects
The data passed reliability and validity tests. The results (Fig. 3) show that people perceive health bene ts from WPs; even during the peak of the epidemic when the perceived bene ts were the lowest, bene ts still outweigh potential risks. The perceived bene ts of visiting wetland parks on mental health were higher than that on physical health, especially during the peak of the epidemic. The perceived health bene ts expected after the Peak were slightly higher than before the Peak: approximately 70% of the respondents perceived the same level of health effects from WPs before and after the Peak; about 20% of the respondents believed that health bene ts have increased after the Peak; in contrast, about 10% of the respondents assumed that perceived health bene ts decreased.

City Level
As shown in Table 1, the RLPHE of the city of residence had a signi cant impact on the perceived physical and mental health bene ts during the Peak and on the perceived mental health bene ts after the Peak (P < 0.05). Respondents in the second RLPHE regions perceived the highest health bene ts, and those in the rst RLPHE areas (the highest-risk area) perceived the lowest physical health bene ts during the Peak and the lowest mental health bene ts after the Peak. In contrast, respondents in third RLPHE regions (medium-risk areas) perceived the lowest mental health bene ts during the Peak.

Community Level
The lockdown level of the respondents' community during the Peak had a signi cant impact on the perceived physical and mental health bene ts after the peak of the epidemic (P < 0.01). Surprisingly, as the degree of community lockdown level increased, the expected perceived physical and mental health bene ts after the peak of the epidemic decreased. Because community lockdown occurred after the outbreak, the differences in the perceived level of mental health bene ts before the Peak was not considered to be caused by community lockdown. Table 1 Impact of the factors (city and community level) (*: P < 0.05, **: P < 0.01) (2010 census data source: National Bureau of Statistics) Most respondents thought that WPs provided habitat, recreation, air puri cation, and aesthetics services (Fig. 4). Habitat and water puri cation were the two ESs that respondents rated as having the greatest perceived physical and mental health bene ts (habitat ranked the rst and water puri cation ranked the second. Air puri cation was essential for physical health, and recreation was important for mental health. Education and social relations were least important for promoting perceived health bene ts.

Wetland Types
Lake was the most popular type among the different wetland types in WPs. Wetland types did not in uence the perception of health effects, except for the perception of physical health effects before the Peak and mental health effects during the Peak in regions with the 2nd level RLPHE (Table 2).

Individual Level
As shown in Table 3, the 45-54 age group perceived the highest physical and mental health bene ts, while the 18-24 age group perceived the lowest physical and mental health bene ts (P < 0.05). Men perceived higher health bene ts than women (P < 0.05). Education levels and occupational status had no in uence on the perceived health effects level before, during and after the Peak. There is a signi cant difference in the change of perceived health bene ts before and after the Peak among various occupational status: compared with before the Peak, the temporarily unemployed and retirees perceived higher mental health bene ts than the other two groups after the Peak (P < 0.05).
Groups with various professional backgrounds had signi cant differences in the perceived health bene ts before the epidemic (P < 0.05); groups with environmental science backgrounds had the highest level of perceived health bene ts. In addition, health experts (persons with medical, nursing, and psychology backgrounds) had signi cantly lower perceptions of mental health bene ts before the epidemic and physical and mental health bene ts after the Peak than other professional groups (P < 0.05). Meanwhile, health experts believed that the health bene ts after the Peak were slightly lower than those before the epidemic, which was opposite to other groups of people.
The self-reported physical health bene t before the epidemic was positively correlated with the perceived physical health bene ts before the Peak (Pearson correlation = 0.06, P < 0.05). The perceived physical or mental health bene ts during and after the Peak were not statistically correlated with the self-reported physical or mental health status on the survey day. And the change of perceived health bene ts was not statistically correlated with the change of selfreported health status.

Discussion
In general, the public perceives wetlands to be bene cial for physical and mental health, which is consistent with the conclusion of previous studies that urban green space and blue-green space are bene cial to people's physical and mental health (see Sect. 1.2.2). A possible reason for the lowest perceived health bene ts during the Peak could be the higher risk of infection. Limited access to WPs during the Peak could also contribute to the low perception of health bene ts. The increase in perceived health bene ts after the Peak shows that inaccessibility to WPs for a period of time may improve perceived health bene ts from WPs.
On the city level, the moderate epidemic risk is associated with greater physical and mental health bene ts for those who visited the park during the Peak. In contrast, very high risks have a negative impact on perceived physical health bene ts, and lower risks are not conducive to perceived mental health bene ts. Surprisingly, for respondents who live in the most severely affected cities during the Peak, the expected psychological healing effect of visiting WPs after the epidemic was lower than those living in other regions.
On the community level, unexpectedly, the perceived level of physical and mental health bene ts after the Peak is negatively associated with the lockdown degree of the community, suggesting that quarantine did not lead to an increase in health-related motivation for visiting WPs.
In terms of WPs level, habitat services were considered to be the most important ecosystem services that promote the perceived health bene ts. The possible reasons are: (1) self-reported happiness is positively correlated with the perceived species richness of birds, butter ies, and plants (Dallimer et al. 2012); (2) the biologically diverse natural environment can improve health by exposure to a pleasant environment or encouraging health promotion behaviours (Lovell et al. 2014); (3) there is a strong positive correlation between vegetation cover and personal well-being. The relationship between human well-being and nature is weakly correlated with changes in species richness, bird abundance, and plant density (Luck et al. 2011). However, habitat services were regarded as indirect health-related ES that affect human health through another service, and the mechanism of their effect on health is still unclear. The importance of habitat, air puri cation and recreation services align with the motivation for visiting WPs (e.g. being close to nature and wildlife habitat, enjoying fresh air and going out for exercises).
On the individual level, this study has found that men perceive higher health bene ts than women when visiting urban blue-green spaces during the Peak.
There is no signi cant gender difference before and after the epidemic. This is different from the result of a previous study based on two of Canada's bluegreen spaces that women usually perceive higher health well-being than men from visiting nature reserves (Lemieux et al. 2012 could be a possible explanation to our result that the temporarily unemployed (e.g. housewives) and retirees (e.g. the elderly) perceived higher mental health bene ts than the other two groups after the Peak. In addition, health experts' perception of mental health bene ts before the epidemic and that of physical and mental health after the Peak were signi cantly lower than other professional groups, which indicate that lay people may have overestimated or health experts may have underestimated the health bene ts of visiting WPs. Besides, health experts believe that the health bene ts after the peak of the epidemic are slightly lower than before the outbreak, while other people have the opposite view. This may be because health experts believe that travel after the peak of the epidemic poses a higher risk.
This study is based on a large number of subjective responses regarding the perceived health effects of WPs. It does not objectively measure the health effects of WPs. Ecosystem disservices could negatively affect the perception of health bene ts. For conducting the questionnaire, it was the assumption that there is little risk of infection by COVID-19 when visiting wetland parks after the Peak, which naturally excludes the effect of some infectious disease-related ecosystem disservices on health perception. Moreover, factors such as the quality, area, and degree of nature of the WPs may affect health (Ekkel and de Vries 2017), and perceived health bene ts. This study is a general analysis based on national sampling. It does not provide a detailed analysis of speci c WPs, including their quality, area, and degree of nature. To control the number of questions and response time, this study did not use more detailed assessment scales (e.g. EQ-5D (Leidl 2009), General Health Questionnaire (White et al. 2013)) to assess health status. This could have an in uence on the respondents' self-reported health status. Most participants had a high level of education, suggesting that they understand the contents of the questionnaire well. Due to the nature of the epidemic, and the restrictions in face-to-face research, this study has to rely on the Internet, thus making it di cult to involve the elderly and non-Internet users.

Conclusion
This research gives an overview of the perceived health effects of WPs in the context of COVID-19 in China to contribute to existing knowledge of health bene ts of urban blue and green spaces and the link between ecosystem services and human health. This study con rms that most people can perceive the health bene ts of WPs. A slightly higher level of perceived health bene ts after the Peak than before indicates that limited access to WPs increases perceived health bene ts. Whilst very high epidemic risks might be said to have a negative impact on perceived physical health bene ts, and lower risks may not be conducive to perceived mental health bene ts, the moderate epidemic risk seems to be associated with greater physical and mental health bene ts for visiting WPs during the Peak. Also, quarantine did not lead to an increase in health-related motivation for visiting WPs. Interestingly, health experts perceived lower health bene ts than laypeople. At the same time, habitat services, which were regarded as indirect health-related ES, were perceived as the most crucial ES for promoting the perceived health bene ts in WPs. Overall, a better understanding of the perception of health bene ts of WPs in the context of COVID-19 can help to provide empirical evidence for managing ecosystem services as delivered by WPs, or green and blue space in general, in the context of COVID-19 or potential future pandemics. Wetland parks that respondents mentioned most frequently (Pictures marked with copyright are source from: www.720yun.com) Figure 3 Perceived health bene t before, during and after the peak of the COVID-19 outbreak Figure 4