Mental health impacts of environmental exposures: A scoping review of evaluative instruments.

To date, much of the health focus of environmental policy has been on preventing physical health impacts of environmental exposures. Recent research has however highlighted increasingly concurrent mental health effects and its consideration is an emerging requirement for many governments and their agencies, yet there are limited universal mental health assessment tools for environmental exposures. This paper details the findings of a scoping review that evaluated assessment tools used to measure psychological impacts from environmental exposures and pollution, as reported in recent peer-reviewed literature (2000-2022). Across the 126 papers identified in our review, a wide range of tools to assess mental health impact were identified. We document a clear recent upswing of research interest in the mental and psychological impacts of environmental exposures, and an overarching concern for air pollution from industry, traffic, and fires. A majority of studies utilised standardised assessment instruments, but there was little consistency in the way that these were combined or deployed. The dominant mental health outcomes of interest in these studies were depression, anxiety, and mental and psychiatric health. The findings of the review identify a need and opportunity to develop a best-practice approach to consistently assess the mental health impacts arising from environmental exposures. Future work is needed to define the most appropriate choice and application of assessment tools to evaluate adverse mental health impacts from environmental exposures. This will support a more universal, coordinated and cross-jurisdiction approach for the assessment, quantification and targeted response to addressing mental health impacts arising from environmental exposures.

Mental illness and increased vulnerability to negative health effects from extreme heat events: a systematic review.

RATIONALE: Across countries, extreme heat events are projected to increase in frequency and intensity because of climate change. Exposure to extreme heat events can have a substantial negative impact on human health, and extant research suggests that individuals with mental illness are particularly vulnerable. To date, there has been no review of evidence regarding this vulnerability to inform response strategies and future research. OBJECTIVE: A systematic review was undertaken to investigate mental illness as an effect modifier of the relationship between heat exposure and morbidity or mortality. METHODS: Six databases (Medline, Embase, Global Health, PsychInfo, CINAHL and Scopus) were searched for studies published between the years 2000 to 2022. Twenty-two observational studies that met the inclusion criteria were investigated through narrative synthesis. The RoBANS tool, ROBIS and GRADE were used to assess the certainty of evidence including the risk of bias. RESULTS: Individuals with mental illness experience worse morbidity and mortality outcomes compared to their counterparts without mental illness in all studies investigating high temperature over a single day. This did not hold for studies examining heatwaves, which reported mixed findings. CONCLUSIONS AND IMPLICATIONS: People with diagnosed mental illness should be targeted for policy and service attention during high temperature days. Further research should investigate specific mental illness and adjust for a wider range of confounding factors.

Mapping social vulnerability indicators to understand the health impacts of climate change: a scoping review.

The need to assess and measure how social vulnerability influences the health impacts of climate change has resulted in a rapidly growing body of research literature. To date, there has been no overarching, systematic examination of where this evidence is concentrated and what inferences can be made. This scoping review provides an overview of studies published between 2012 and 2022 on social vulnerability to the negative health effects of climate change. Of the 2115 studies identified from four bibliographic databases (Scopus, Web of Science, PubMed, and CAB Direct), 230 that considered indicators of social vulnerability to climate change impacts on health outcomes were selected for review. Frequency and thematic analyses were conducted to establish the scope of the social vulnerability indicators, climate change impacts, and health conditions studied, and the substantive themes and findings of this research. 113 indicators of social vulnerability covering 15 themes were identified, with a small set of indicators receiving most of the research attention, including age, sex, ethnicity, education, income, poverty, unemployment, access to green and blue spaces, access to health services, social isolation, and population density. The results reveal an undertheorisation and few indicators that conceptualise and operationalise social vulnerability beyond individual sociodemographic characteristics by identifying structural and institutional dimensions of vulnerability, and a preponderance of social vulnerability research in high-income countries. This Review highlights the need for future research, data infrastructure, and policy attention to address structural, institutional, and sociopolitical conditions, which will better support climate resilience and adaptation planning.

Parental co-residence and young adults' mental health.

The growing trend towards young adults staying in the parental home has garnered much recent scholarly interest. However, less is known about which young adults are living at home, and the impacts this has over young adults' lives. Using The Household, Income and Labour Dynamics in Australia (HILDA) dataset, this study examines the profiles of co-residing young adults and how these have changed over the first two decades of the 21st century. It then analyses the associations between co-residence and young adults' mental health, applying a propensity score modelling approach to determine differences in mental health between young adults living at home and their counterparts living independently. Results indicate that rates of co-residence have increased over the 2000s, most steeply amongst those residing outside of major cities (by 46%), older adults (by 36%), females (by 28%), and low-income groups (by 10%). Findings show a significant negative association between co-residence and mental health (a 4-point difference on the 100-point scale, 95% CI -5.93, -2.14). However, the greatest differential in mental health between co-resident and independent young adults is observed amongst those for whom rates of co-residence have increased most dramatically, i.e., females and older adults (a 6-point difference in mental health) and residents of regional and rural areas (a 5-point difference in mental health). We situate this discussion in the context of intensifying housing market constraints, considering how the transformation of the Australian housing system into a vehicle for wealth accumulation has generated barriers to residential independence.

An Australian housing conditions data infrastructure.

For the past two decades, researchers and policy makers have known very little about conditions within Australia's housing stock due to a lack of systematic and reliable data. In 2022, a collaboration of Australian universities and researchers commissioned a large survey of 22,550 private rental, social rental and homeowner households to build a data infrastructure on the household and demographic characteristics, housing quality and conditions in the Australian housing stock. This is the third and largest instalment in a national series of housing conditions data infrastructures.

Group A Streptococcus Vaccine Targeting the Erythrogenic Toxins SpeA and SpeB Is Safe and Immunogenic in Rabbits and Does Not Induce Antibodies Associated with Autoimmunity.

Group A streptococcus (GAS) is a global pathogen associated with significant morbidity and mortality for which there is currently no licensed vaccine. Vaccine development has been slow, mostly due to safety concerns regarding streptococcal antigens associated with autoimmunity and related complications. For a GAS vaccine to be safe, it must be ensured that the antigens used in the vaccine do not elicit an antibody response that can cross-react with host tissues. In this study, we evaluated the safety of our GAS vaccine candidate called VaxiStrep in New Zealand White rabbits. VaxiStrep is a recombinant fusion protein comprised of streptococcal pyrogenic exotoxin A (SpeA) and exotoxin B (SpeB), also known as erythrogenic toxins, adsorbed to an aluminum adjuvant. The vaccine elicited a robust immune response against the two toxins in the rabbits without any adverse events or toxicity. No signs of autoimmune pathology were detected in the rabbits' brains, hearts, and kidneys via immunohistochemistry, and serum antibodies did not cross-react with cardiac or neuronal tissue proteins associated with rheumatic heart disease or Sydenham chorea (SC). This study further confirms that VaxiStrep does not elicit autoantibodies and is safe to be tested in a first-in-human trial.

Housing typologies and asthma: a scoping review.

Asthma is related to triggers within the home. Although it is recognised that triggers likely occur due to characteristics of housing, these characteristics have not been comprehensively reviewed, and there is a paucity of housing-focused interventions to reduce asthma and asthma symptoms. Following five steps identified by Arksey and O'Malley, we conducted a scoping review of published evidence on the associations between asthma and housing characteristics. We searched three electronic databases (PubMed, Scopus, Web of Science), identifying 33 studies that met our inclusion criteria. Through an iterative approach, we identified nine housing characteristics relevant to asthma onset or exacerbation, categorised as relating to the surrounding environment (location), the house itself (dwelling), or to conditions inside the home (occupancy). We conceptualise these three levels through a housing typologies framework. This facilitates the mapping of housing characteristics, and visualises how they can cluster and overlap to exacerbate asthma or asthma symptoms. Of the three levels in our framework, associations between asthma and locational features were evidenced most clearly in the literature reviewed. Within this category, environmental pollutants (and particularly air pollutants) were identified as a potentially important risk factor for asthma. Studies concerning associations between dwelling features and occupancy features and asthma reported inconsistent results, highlighting the need for greater research in these areas. Interpreting housing-related asthma triggers through this framework paves the way for the identification and targeting of typologies of housing that might adversely affect asthma, thus addressing multiple characteristics in tandem rather than as isolated elements.

The total health gains and cost savings of eradicating cold housing in Australia.

BACKGROUND: Cold indoor temperature (<18 °C) is associated with hypertension-related and respiratory disease, depression, and anxiety. We estimate total health, health expenditure and income impacts of permanently lifting the temperature in living areas of the home to 18 °C in cold homes in South-eastern Australia (N = 17 million). METHODS: A proportional multistate lifetable model was used to estimate health adjusted life years (HALYs), health expenditure and income earnings, over the remainder of the lifespan of the population alive in 2021 (3% discount rate). Multiple data were integrated including the prevalence of cold housing (5.87%; mean temperature 15 °C), the effect of temperature to hypertension-related, respiratory disease, depression and anxiety. FINDINGS: Eradicating cold housing was predicted to lead to 89,600 (95% UI 47,700 to 177,000) lifetime HALYs gained over the population's remaining lifespan, nearly half of which occurred from 2021 to 2040. Respiratory disease (32.4%) and mental illness (60.6%) made large contributions to HALYs gained, but also had large uncertainty (95% UI 30.0%-42.9% and 45.1%-64.6%, respectively) due to uncertain estimates of their magnitude of causal association with cold housing. Health gains per capita were 6.1 times greater (95% UI 4.7 to 8.1) among the most compared to least deprived quintile. From 2021 to 2040, health expenditure decreased by AUD$0.87 billion (0.35-1.98) and income earnings increased by AUD$4.35 billion (1.89-9.81). INTERPRETATION: Eliminating cold housing would lead to substantial health gains, reductions in health inequalities, savings in health expenditure, and productivity gains. Next steps require research to reduce uncertainty about the magnitude of causal associations of cold with mental and respiratory health.

Green and blue spaces, COVID-19 lockdowns, and mental health: An Australian population-based longitudinal analysis.

Australia experienced some of the world's longest and most stringent lockdowns during the COVID-19 pandemic. While lockdown measures had consequences for mental health, investigation is lacking on the potential for green and blue space coverage within people's local environments to ameliorate the impact of lockdowns with varied lengths using longitudinal cohorts. This study examined the impact of lockdown durations on population mental health and tests the effect modification of neighbourhood green and inland and coastal blue space coverage in metropolitan areas. We merged population-based longitudinal data on more than 11,000 individuals collected over a ten-year period from 2012 to 2021 with national land use data describing green and blue space coverage. We used fixed effect models to estimate the relationship between lockdowns (with different durations and staggered introduction) and mental health, controlling for sociodemographic, health, and geographical confounders, and tested the significance of effect modification of green and blue space. Results show that extended lockdowns led to considerably larger decreases in mental health (COVID-y1: -2.66, 95%CI: -3.43, -1.89; COVID-y2: -2.65, 95%CI: -3.33, -1.97) relative to short lockdowns. The mental health effect of lockdowns was smaller where green spaces and inland and coastal blue spaces were available. Effect modification was statistically significant for green space, with smaller negative mental health effects observed where there was sizeable green space coverage, particularly during long lockdowns (COVID-y1: -2.69, 95%CI: -3.63, -1.76 for coverage <5%; -3.27, 95%CI: -4.70, -1.84 for coverage 5%-10%; -0.60, 95%CI: -2.03, 0.83 for coverage ≥30%; COVID-y2: -2.74, 95%CI: -3.62, -1.87 for coverage <5%, -2.95, 95%CI: -3.98, -1.92 for coverage 5%-10%; -2.08, 95%CI: -3.28, -0.88 for coverage ≥30%). Findings support the consideration of nature exposure to improve people's mental wellbeing and resilience when designing lockdown measures in response to future public health emergencies.

The effect of energy poverty on mental health, cardiovascular disease and respiratory health: a longitudinal analysis.

Background: Houses in mild-climate countries, such as Australia, are often ill-equipped to provide occupants protection during cold weather due to their design. As a result, we rely on energy to warm homes, however, energy is becoming increasingly expensive, and evidence is emerging of a sizable burden to population health of being unable to afford to warm homes causing exposure to cold indoor temperatures. Methods: We use a large longitudinal sample of adult Australians (N = 32,729, Obs = 288,073) collected annually between 2000 and 2019 to estimate the relationship between exposure to energy poverty and mental health (SF-36 mental health score), and a smaller sample from waves collected in 2008-9, 2012-13, and 2016-17 (N = 22,378, Obs = 48,371) to estimate the relationship between energy poverty and onset of asthma, chronic bronchitis or emphysema, hypertension, coronary heart disease, and depression/anxiety. Fixed effects and correlated random-effects regression was used in models. As exposure and outcomes were self-reported, we tested alternative specifications of each to examine bias from measurement error. Findings: When people can no longer afford to warm their homes, their mental health declines significantly (by 4.6-points on the SF-36 mental health scale, 95% CI -4.93 to -4.24), their odds of reporting depression/anxiety or hypertension increases by 49% (OR 1.49, 95% CI 1.09 to 2.02) and 71% (OR 1.71, 95% CI 1.13 to 2.58) respectively. The findings for the decline in mental health were supported in additional analyses that tested alternative specifications of the exposure measure, including co-resident verification of respondent reporting of being able to afford to warm the home. Support for an effect of energy poverty on hypertension was less clearly supported in these same sensitivity models. There was little evidence of an effect of energy poverty on asthma or chronic bronchitis onset in this adult population noting, however, that we could not examine exacerbation of symptoms. Interpretation: Reducing exposure to energy poverty should be considered as an intervention with clear benefits for mental health and potential benefits for cardiovascular health. Funding: National Health and Medical Research Council, Australia.

Cold housing environments: defining the problem for an appropriate policy response.

Researchers across disciplines are increasing attention to cold housing environments. Public health, environmental and social sciences, architecture, and engineering each define and measure cold housing environments differently. Lack of standardisation hinders our ability to combine evidence, determine prevalence, understand who is most at risk--and to formulate policy responses. We conducted a systematic, cross-disciplinary review of literature to document the measures used. We examined benefits and limitations of each approach and propose a conceptualisation of cold housing: where temperature is too low to support optimal health and wellbeing of inhabitants, measured using one or a combination of economic, 'objective', or subjective approaches. More accurate data on home temperatures for all population groups, combined with an understanding of factors leading to cold homes, will enable appropriate policy response to reduce adverse health effects and costs. Policies targeting better building standards and energy subsidies both improve temperature conditions in housing environments.

Health and housing consequences of climate-related disasters: a matched case-control study using population-based longitudinal data in Australia.

BACKGROUND: Understanding the role of how people are housed in reducing the long-term health and housing effects of climate-related disasters is crucial given our changing climate. We examine long-term health and housing trajectories and health effects of climate-related disasters in relation to housing vulnerabilities over a decade. METHODS: We conducted a matched case-control study using longitudinal population-based data from the Household, Income and Labour Dynamics in Australia survey. We included data from people whose homes had been damaged by climate-related disasters (eg, flood, bushfire, or cyclone) between 2009 and 2019 and matched control cohorts with similar sociodemographic profiles who had not been exposed to disaster-related home damage during this period. We included data from de-identified individuals with at least 1 year of data before disaster and 3 years after disaster. One-to-one nearest neighbour matching was performed on the basis of demographic, socioeconomic, housing, health, neighbourhood, location, and climate characteristics 1 year before disaster. Conditional fixed-effects models for matched case-control groups were used to assess health trajectories, using eight quality-of-life domains on mental, emotional, social, and physical wellbeing, and housing trajectories, using three housing aspects of cost (ie, housing affordability and fuel poverty), security (ie, residential stability and tenure security), and condition (ie, housing quality and suitability). FINDINGS: Exposure to home damage from climate-related disasters had significant negative effects on people's health and wellbeing at disaster year (difference between exposure and control groups in mental health score was -2·03, 95% CI -3·28 to -0·78; in social functioning score was -3·95, -5·57 to -2·33; and in emotional wellbeing score was -4·62, -7·06 to -2·18), with some effects lasting for 1-2 years after disaster. These effects were more severe for people who had housing affordability stress or were living in poor quality housing before the disaster. People in the exposure group had a slight increase in housing and fuel payment arrears following disasters. Homeowners had increased housing affordability stress (1 year after disaster: 0·29, 95% CI 0·02 to 0·57; 2 years after disaster: 0·25, 0·01 to 0·50), renters had a higher prevalence of acute residential instability (disaster year: 0·27, 0·08 to 0·47), and people who were exposed to disaster-related home damage had a higher prevalence of forced moves than did the control group (disaster year: 0·29, 0·14 to 0·45). INTERPRETATION: Findings support the need for recovery planning and resilience building to consider housing affordability, tenure security, and housing condition. Interventions might require divergent strategies for populations in different precarious housing circumstances, and policies should target long-term housing support services for highly vulnerable groups. FUNDING: The National Health and Medical Research Council Centre of Research Excellence in Healthy Housing, University of Melbourne Affordable Housing Hallmark Research Initiative Seed Funding, Australian Research Council's Centre of Excellence for Children and Families over the Life Course, and Lord Mayor's Charitable Foundation.

Vulnerability and recovery: Long-term mental and physical health trajectories following climate-related disasters.

Extreme weather and climate-related disaster events are associated with a range of adverse health outcomes. People are not equally vulnerable to the adversity, experiencing varied patterns of long-term health trajectories in recovery depending on their vulnerabilities, capacities, and resiliencies. This study aims to identify latent mental and physical health trajectories and their associations with person- and place-based pre-disaster predictors. Using an Australian, population-based, longitudinal dataset spanning 2009-19, group-based multi-trajectory modelling was applied to identify the distinct mental, social, emotional, and physical health trajectories of people who had experienced damage to their home following a climate-related disaster event. Multinomial logistic regression was used to assess a series of social vulnerability predictors (demographic, socioeconomic, housing, health, neighbourhood, and geographical) of health patterns. We identified three distinct health trajectories. Most individuals experienced small or minimal health impacts at the time of the disaster year followed by a fast recovery. However, one-fifth of the exposed population were severely affected during and post disaster. This cohort had the worst mental and physical health prior to the disaster and experienced the largest decreases in mental and physical health and the lowest recoveries. Pre-existing mental and physical conditions were the most substantial risk factors, increasing the probability of experiencing high impact and slow recovery by 61% for mental health and 51% for physical health. In addition, vulnerability in the form of housing affordability stress, lower household income, and lack of community attachment, participation and safety were also significant independent risk factors for ongoing post-disaster health problems. Critically, people's mental and physical health recovery is dependent on pre-disaster vulnerabilities in health, resource access, and capacities. These findings could assist policymakers and health practitioners to more effectively target people most at risk and design prevention and response strategies to prevent the exacerbation of poor health and wellbeing.

Evidence to guide ethical decision-making in the management of older people living in squalor: a narrative review.

Older people living in squalor present healthcare providers with a set of complex issues because squalor occurs alongside a variety of medical and psychiatric conditions, and older people living in squalor frequently decline intervention. To synthesise empirical evidence on squalor to inform ethical decision-making in the management of squalor using the bioethical framework of principlism. A systematic literature search was conducted using Medline, Embase, PsycINFO and CINAHL databases for empirical research on squalor in older people. Given the limited evidence base to date, an interpretive approach to synthesis was used. Sixty-seven articles that met the inclusion criteria were included in the review. Our synthesis of the research evidence indicates that: (i) older people living in squalor have a high prevalence of frontal executive dysfunction, medical comorbidities and premature deaths; (ii) interventions are complex and require interagency involvement, with further evaluations needed to determine the effectiveness and potential harm of interventions; and (iii) older people living in squalor utilise more medical and social resources, and may negatively impact others around them. These results suggest that autonomous decision-making capacity should be determined rather than assumed. The harm associated with squalid living for the older person, and for others around them, means a non-interventional approach is likely to contravene the principles of non-maleficence, beneficence and justice. Adequate assessment of decision-making capacity is of particular importance. To be ethical, any intervention undertaken must balance benefits, harms, resource utilisation and impact on others.

Housing and health: an updated glossary.

Recent crises have underscored the importance that housing has in sustaining good health and, equally, its potential to harm health. Considering this and building on Howden-Chapman's early glossary of housing and health and the WHO Housing and Health Guidelines, this paper introduces a range of housing and health-related terms, reflecting almost 20 years of development in the field. It defines key concepts currently used in research, policy and practice to describe housing in relation to health and health inequalities. Definitions are organised by three overarching aspects of housing: affordability (including housing affordability stress (HAS) and fuel poverty), suitability (including condition, accessibility and sustainable housing) and security (including precarious housing and homelessness). Each of these inter-related aspects of housing can be either protective of, or detrimental to, health. This glossary broadens our understanding of the relationship between housing and health to further promote interdisciplinarity and strengthen the nexus between these fields.

Estimating cardiovascular health gains from eradicating indoor cold in Australia.

BACKGROUND: Exposure to cold indoor temperature (< 18 degrees Celsius) increases cardiovascular disease (CVD) risk and has been identified by the WHO as a source of unhealthy housing. While warming homes has the potential to reduce CVD risk, the reduction in disease burden is not known. We simulated the population health gains from reduced CVD burden if the temperature in all Australian cold homes was permanently raised from their assumed average temperature of 16 degrees Celsius to 20 degrees Celsius. METHODS: The health effect of eradicating cold housing through reductions in CVD was simulated using proportional multistate lifetable model. The model sourced CVD burden and epidemiological data from Australian and Global Burden of Disease studies. The prevalence of cold housing in Australia was estimated from the Australian Housing Conditions Survey. The effect of cold indoor temperature on blood pressure (and in turn stroke and coronary heart disease) was estimated from published research. RESULTS: Eradication of exposure to indoor cold could achieve a gain of undiscounted one and a half weeks of additional health life per person alive in 2016 (base-year) in cold housing through CVD alone. This equates to 0.447 (uncertainty interval: 0.064, 1.34; 3% discount rate) HALYs per 1,000 persons over remainder of their lives through CVD reduction. Eight percent of the total health gains are achievable between 2016 and 2035. Although seemingly modest, the gains outperform currently recommended CVD interventions including persistent dietary advice for adults 5-9% 5 yr CVD risk (0.017 per 1000 people, UI: 0.01, 0.027) and persistent lifestyle program for adults 5-9% 5 yr CVD risk (0.024, UI: 0.01, 0.027). CONCLUSION: Cardiovascular health gains alone achievable through eradication of cold housing are comparable with real-life lifestyle and dietary interventions. The potential health gains are even greater given cold housing eradication will also improve respiratory and mental health in addition to cardiovascular disease.

Environmental Noise Exposure and Mental Health: Evidence From a Population-Based Longitudinal Study.

INTRODUCTION: Exposure to environmental noise from within homes has been associated with poor mental health. Existing evidence rests on cross-sectional studies prone to residual confounding, reverse causation, and small sample sizes, failing to adequately consider the causal nature of this relationship. Furthermore, few studies have examined the sociodemographic distribution of noise exposure at a country level. METHODS: The study, conducted in 2021, examined the impact of environmental noise from road traffic, airplanes, trains, and industry on mental health and psychological distress as reported by 31,387 respondents using a 19-year longitudinal data set in Australia (2001‒2019). To improve the capacity to make causal inference and reduce bias from measurement error, reverse causation, and unobserved confounders, analyses used instrumental variables, fixed-effects models, and an aggregated area-level measure of noise exposure. Utilizing the large-scale national data set, sociospatial distributions of noise exposure were described. RESULTS: Private and public rental tenants, lone parents, residents of socioeconomically disadvantaged areas, and those with long-term health conditions were more likely to report residential noise exposure. This exposure to noise was consistently associated with poorer mental health (self-reported noise: ß= -0.58; 95% CI= -0.76, -0.39; area-level noise: ß= -0.43; 95% CI= -0.61, -0.26), with the relationship strongest for traffic noise (ß= -0.79; 95% CI= -1.07, -0.51). Notably, when noise exposure decreased over time, there was an increase in mental health (ß= 0.43; 95% CI= 0.14, 0.72). CONCLUSIONS: The study provides strong evidence of a negative mental health effect of perceived residential noise, and the results have implications for healthy home design and urban planning. These findings should be validated with further studies that measure noise intensity and housing quality.

Impact of COVID-19 shocks, precarity and mediating resources on the mental health of residents of share housing in Victoria, Australia: an analysis of data from a two-wave survey.

OBJECTIVES: COVID-19 lockdown measures have challenged people's mental health, especially among economically vulnerable households. The objective of this study was to investigate the impact of exposure to COVID-19 shocks (defined as job loss, living cost pressures and changing housing conditions throughout the lockdown period) and double precarity (defined as precarity in housing and employment) on mental health outcomes for members of share households as well as the mediating effects of a range of resources. DESIGN: We conducted a two-wave survey of occupants of share housing in June and October 2020 during a prolonged period of population lockdown. Research design involved fixed effects ordered logit regression models to assess the mental health consequences of baseline precarity and COVID-related shocks. SETTING: Victoria, Australia. PARTICIPANTS: We surveyed 293 occupants of share houses (mean age 34 SD 11.5, 56% female). Members of share houses (where individuals are unrelated adults and not in a romantic relationship) are more likely to be young, casually employed, visa-holders and low-income. OUTCOME MEASURES: We measured household composition, housing and employment precarity, access to government support, household crowding, social networks and COVID-19 shocks. We used a self-reported measure of mental health. RESULTS: Those exposed to COVID-19 shocks reported a 2.7 times higher odds of mental health deterioration (OR 2.7, 95% CI 1.53 to 4.85). People exposed to double precarity (precarity in both housing and employment) reported 2.4 times higher odds of mental health deterioration (OR 2.4, 95% CI 0.99 to 5.69). Housing inadequacy and lack of access to sufficient government payments explained 14.7% and 7% of the total effect of double precarity on mental health, respectively. CONCLUSIONS: Results indicate that residents of group households characterised by pre-existing precarity were vulnerable to negative mental health effects during lockdown. Access to sufficient government payments and adequate housing buffered this negative effect.