BMC Public Health 2009, 9:221 http://www.biomedcentral.com/1471-2458/9/221 Background Since the mid-19th century, public health practitioners have understood that people's residential environment and housing conditions influence health outcomes [1,2]. Crime is among those factors suggested to be most strongly related to health in the housing environment, both by direct exposure and indirectly by residents' per- ception of feeling unsafe [3,4]. Previous research suggests that several factors influence residents' perceived safety in a neighbourhood. These factors can be divided into three main themes: crime experiences and fear of crime, demo- graphic characteristics, and the design and quality of the residential environment [5-9]. Crime experiences and fear of crime Crime in a neighbourhood has been recognized as a key stressor in the residential environment, when measured in absolute numbers of reported crimes in the neighbour- hood and as residents' personal experience of being a crime victim. Fear of crime has also been found to have a significant negative influence on residential quality, and may have a negative impact on residents' mental health comparable to crime itself [10,11]. Fear of crime is related to risk assessment, which depends on the concentration of objective risk in time and space, and on the presence of subjective perceived early signs of imminent hazard [12]. Prolonged safety-related worry and fear of crime is suggested to yield behaviour modifi- cation as it potentially decreases physical activity and lim- its the residents' personal freedom. A consequence of safety-related worry may therefore be 'time-space inequal- ities' with implications for physical and mental health [13,14]. However, crime is an elusive factor with many facets. Vio- lent crime in the immediate environment does not seem to have a great deal in common with every day offences, such as car theft or damage, in relation to perceived safety. Another aspect is the way the local newspaper communi- cates crime in specific neighbourhoods. Newspaper head- lines about local crime may result in attitudes that divide neighbourhoods into desirable and undesirable areas. Stories retold by neighbours who have been victims of crime themselves may result in negative attitudes, and increase the perception of isolation among residents [15,16]. There is thus a community-based contagious process affecting residents' perceived safety in specific areas through the influence of reports in the media and/or others around them. Demographic characteristics Earlier studies have reported that individual variables such as gender, age, social and economic resources influ- ence the potential risk of becoming a crime victim and fear of crime. Even though women are subject to lower crime victim rates than men, they are found to fear crime more [17,18]. Similarly, the elderly fear crime to a higher degree than young adults, even though they have the low- est risk of becoming a victim themselves [19]. Further, Halpern [20] found that to be unmarried or socially dis- connected from conventional society in the area where you live, the more likely you are to become a victim of crime. At neighbourhood level, the proportion of residential het- erogeneity, level of education, mobility rate and density of the neighbourhood were found to be associated with per- ception of safety of the people living there [21,22]. Design and quality of the residential environment Newman [23] presented the model of 'defensible space' in planning and argued for a correlation between design and function of the built environment and crime rates. He observed that in small-scale neighbourhoods in which the residents have good surveillance and control of shared outdoor space, the possibility of achieving lower factual crime rates and better maintenance is higher than in neighbourhoods without the possibility of this informal control. Newman also observed that residents who had to share a common entrance and staircase to reach their dwelling reported more perceived insecurity and a lower sense of belonging to the neighbourhood. Land-use mix is another aspect that has been suggested to influence crime rates. For instance, non-residential prop- erty, such as shops, car-parking and public spaces, has been found to increase the number of crimes [24]. There is also evidence that visible signs such as litter and graffiti in an area communicate anti-social behaviour and how seriously the risk of becoming a crime victim has to be taken. The perception that one's neighbourhood is unsafe is likely a constant psychological irritant [25,26]. Several studies have suggested that perceptions of safety and fear of crime play an important role in explaining area differ- ences in health through emotional and behavioural responses on neighbourhood quality [27-29]. Factors such as the appearance of the neighbourhood and the reputation of the area have thus been found to impact on residential well-being [30,31] but few studies have focused on how these characteristics influence safety- related concerns. Due to the fact that neighbourhoods are embedded in a community context in which reputations are developed, the rumours that evolve may affect resi- dents' sense of belonging in different neighbourhoods in different ways. If a neighbourhood is held to have a spe- cific reputation, this will influence the way its residents are perceived by others. Depending on the character of the Page 2 of 11 (page number not for citation purposes)