Wearing a face mask in public has not been recommended for preventing influenza virus infection [1]. Even though a face mask might provide some protection from inhaling larger droplets and hindering hand contact to the mouth and nose, the mask itself does not fit tightly enough to block droplets from entering between the face and mask [2]. In some Asian countries including Japan, many healthy people wear face masks in public during the influenza season, with an expectation that it helps prevent respiratory infections [3, 4].

The effectiveness of wearing a face mask in certain settings with a high risk of influenza infection such as staying with influenza patients at home and shared living setting has been demonstrated in some studies. When a face mask is used correctly by infected individuals, it may help prevent household transmission by hindering the spread of infective respiratory droplets [5–7]. Wearing a facemask as well as adopting positive hand hygiene practices has been shown to reduce respiratory illness in shared living settings among young adults [8, 9] with a relatively high compliance when wearing a mask. However, some other research has shown that compliance when wearing a face mask is low, especially in non-randomized studies [10, 11].

On the other hand, it is reasonable to suggest that wearing face masks in the community might be an indicator of positive personal hygiene practices, health behaviors and perceptions of disease prevention. Despite this fact, no studies appear to have explored the association between face mask use and other personal hygiene practices and health behaviors. Aside from the potential public health benefits, examining these associations would also be very helpful to help minimize statistical confounding during research on the effectiveness of face masks in non-randomized studies. The aim of this study, therefore, was to determine if wearing a face mask in public is associated with other hygiene practices and health behaviors among Japanese adults.

This study provides some compelling evidence that wearing a face mask in public is associated with other positive personal hygiene practices and health behaviors among Japanese adults. Participants who wore a face mask were more likely to report practicing additional preventive hygiene measures including hand washing, gargling, avoiding crowds and close contact with ill people, having good quality sleep and being vaccinated against influenza.

Previous research conducted elsewhere has also elucidated the prevalence of hygiene practices with respect to influenza. A study from Korea for example, conducted during the early phases of the influenza pandemic in 2009, reported that 57% of female and 34% of male participants washed their hands five times a day [14]. Similarly, Lau and colleagues reported that 22% of their study subjects in Hong Kong wore face masks regularly in public during the early phases of the pandemic, while 45% of them washed their hands more than 10 times [15]. The prevalence of positive hygiene practices reported in studies conducted during the 2009 influenza pandemic appears to be higher than during the ‘general’ influenza season. In fact, a much lower prevalence of preventive measures than that of the 2009 pandemic have been observed, even in outbreak situations. For example, less than 10% of participants implemented preventive measures (including frequent hand washing, wearing face masks and getting more sleep) in a study of Dutch and Finnish individuals during the SARS outbreak of 2003 [16]. Presumably, the risk of being affected by a disease within a community and country influences the distribution and uptake of preventive hygiene measures.

We hypothesize that various factors probably contributed to the significant associations between face mask use and other hygiene practices and health behaviors during the Japanese influenza season. Firstly, they might reflect a high level of social and cultural acceptance of hygiene practices and health behaviors in this country [4], generally, as personal preventive measures are deeply engrained in cultural attitudes and behaviors within the Japanese community – including in the workplace [17]. All hygiene practices and health behaviors investigated during the current study are recommended by Japanese health authorities such as the Ministry of Health, Labour, and Welfare. Secondly, it is reasonable to suspect that individual risk perceptions might have influenced the statistical association we elucidated in the current study. An investigation from Hong Kong, for example, looked at hygiene behaviors during the early phases of the influenza A(H1N1) 2009 pandemic [15] and revealed that wearing a face mask in public was associated with a perception of the effectiveness of face mask use versus the dangers of influenza A(H1N1). Although previous studies have been conducted in culturally different settings and at different times (such as in the early phase of a pandemic), the current research nevertheless suggests that significant associations might have been influenced by individual perceptions. As such, further studies regarding the impact of individual perceptions are needed for verification [18].

Although the effectiveness of wearing a face mask for preventing infectious diseases has been investigated in various other studies [5, 7, 9, 10, 19, 20], most have not considered possible associations between wearing a face mask and additional hygiene practices. However, we should note that a randomized controlled study which allocated face masks only revealed no statistically significantly differences in hand hygiene practices [8]. As such, it can be seen that any additional research to assess the contribution of face masks in preventing respiratory infections, will clearly need to monitor other health behaviors as part of their investigation.

Given that our research was one of the first of its kind, we acknowledge that the study might have incurred some limitations. Firstly, the generalizability of the results might be limited because the study participants were recruited using an online survey tool. This population would, presumably, have had internet access and therefore, might be more aware of preventive measures against influenza – especially those promoted on the internet [21]. In addition, as this study utilized an internet survey, we do not have any information on the non-respondents. Secondly, there is the possibility that it may be difficult for people to accurately recall their hygiene practices of the previous year in detail. A bias may exist among people who wear masks if they are more inclined to report undertaking other positive hygiene practices at higher rates than individuals who report lower mask use. Thirdly, as our current study was conducted in only one country (Japan), further research is therefore needed to determine the situation in other countries, especially those with a relatively lower rate of face mask use in the general population. Lastly, given that our study was cross-sectional in design, we are unable to confirm the existence of causal relationships.

Overall, this study suggests that wearing a face mask in public may be associated with other personal hygiene practices and health behaviors among Japanese adults. Rather than preventing influenza itself, face mask use might instead be a marker of additional, positive hygiene practices and other favorable health behaviors in the same individuals.