Air quality and mental health: evidence, challenges and future directions.

BACKGROUND: Poor air quality is associated with poor health. Little attention is given to the complex array of environmental exposures and air pollutants that affect mental health during the life course. AIMS: We gather interdisciplinary expertise and knowledge across the air pollution and mental health fields. We seek to propose future research priorities and how to address them. METHOD: Through a rapid narrative review, we summarise the key scientific findings, knowledge gaps and methodological challenges. RESULTS: There is emerging evidence of associations between poor air quality, both indoors and outdoors, and poor mental health more generally, as well as specific mental disorders. Furthermore, pre-existing long-term conditions appear to deteriorate, requiring more healthcare. Evidence of critical periods for exposure among children and adolescents highlights the need for more longitudinal data as the basis of early preventive actions and policies. Particulate matter, including bioaerosols, are implicated, but form part of a complex exposome influenced by geography, deprivation, socioeconomic conditions and biological and individual vulnerabilities. Critical knowledge gaps need to be addressed to design interventions for mitigation and prevention, reflecting ever-changing sources of air pollution. The evidence base can inform and motivate multi-sector and interdisciplinary efforts of researchers, practitioners, policy makers, industry, community groups and campaigners to take informed action. CONCLUSIONS: There are knowledge gaps and a need for more research, for example, around bioaerosols exposure, indoor and outdoor pollution, urban design and impact on mental health over the life course.

Assessing the health risk of living near composting facilities on lung health, fungal and bacterial disease in cystic fibrosis: a UK CF Registry study.

AIM: To explore the health risk of living near permitted composting sites (PCSs) on disease severity in children and adults with cystic fibrosis (CF) across the UK.  METHODS: A semi-individual cross-sectional study was used to examine the risk of disease severity in people with CF (pwCF) within and beyond 4 km of PCSs in the UK in 2016. All pwCF registered in the UK CF Registry were eligible for this study. Linear and Poisson regressions, adjusted for age, gender, genotype, BMI, Pseudomonas aeruginosa and deprivation, were used to quantify associations between distance to a PCS and percent predicted forced expiratory volume in one second (ppFEV1), pulmonary exacerbations (#IVdays), and fungal and bacterial infections. RESULTS: The mean age of the 9,361 pwCF (3,931 children and 5,430 adults) studied was 20.1 (SD = 14.1) years; 53.3% were male; and 49.2% were homozygous F508del. Over 10% of pwCF (n = 1,015) lived within 4 km of a PCS. We found no statistically significant difference in ppFEV1 and #IVdays/year in children. However, in adults, ppFEV1 was -1.07% lower (95% confidence interval (CI): -2.29%, 0.16%) and #IVdays/year were 1.02 day higher (95%CI: 1.01, 1.04) within 4 km of a PCS. Furthermore, there were statistically significant differences in mean ppFEV1 in CF adults with Aspergillus fumigatus (58.2.% vs 62.0%, p = 0.005) and Candida spp. (56.9% vs 59.9%, p = 0.029) residing within 4 km of a PCS. No associations were identified for allergic bronchopulmonary aspergillosis, P. aeruginosa or Staphylococcus aureus. CONCLUSIONS: This novel national study provides evidence that adults with CF living near a PCS may experience small reductions in lung function, an increased risk of pulmonary exacerbations, and more frequent fungal infections. If confirmed by studies using refined exposure assessment methods accounting for bioaerosol dispersion, these results could have important implications for the living environment of pwCF.

A systematic review of outdoor airborne fungal spore seasonality across Europe and the implications for health.

Fungal spores make up a significant proportion of organic matter within the air. Allergic sensitisation to fungi is associated with conditions including allergic fungal airway disease. This systematic review analyses outdoor fungal spore seasonality across Europe and considers the implications for health. Seventy-four studies met the inclusion criteria, the majority of which (n = 64) were observational sampling studies published between 1978 and 2020. The most commonly reported genera were the known allergens Alternaria and Cladosporium, measured in 52 and 49 studies, respectively. Both displayed statistically significant increased season length in south-westerly (Mediterranean) versus north-easterly (Atlantic and Continental) regions. Although there was a trend for reduced peak or annual Alternaria and Cladosporium spore concentrations in more northernly locations, this was not statistically significant. Peak spore concentrations of Alternaria and Cladosporium exceeded clinical thresholds in nearly all locations, with median peak concentrations of 665 and 18,827 per m3, respectively. Meteorological variables, predominantly temperature, precipitation and relative humidity, were the main factors associated with fungal seasonality. Land-use was identified as another important factor, particularly proximity to agricultural and coastal areas. While correlations of increased season length or decreased annual spore concentrations with increasing average temperatures were reported in multi-decade sampling studies, the number of such studies was too small to make any definitive conclusions. Further, up-to-date studies covering underrepresented geographical regions and fungal taxa (including the use of modern molecular techniques), and the impact of land-use and climate change will help address remaining knowledge gaps. Such knowledge will help to better understand fungal allergy, develop improved fungal spore calendars and forecasts with greater geographical coverage, and promote increased awareness and management strategies for those with allergic fungal disease.

Risk of respiratory hospital admission associated with modelled concentrations of Aspergillus fumigatus from composting facilities in England.

Bioaerosols have been associated with adverse respiratory-related health effects and are emitted in elevated concentrations from composting facilities. We used modelled Aspergillus fumigatus concentrations, a good indicator for bioaerosol emissions, to assess associations with respiratory-related hospital admissions. Mean daily Aspergillus fumigatus concentrations were estimated for each composting site for first full year of permit issue from 2005 onwards to 2014 for Census Output Areas (COAs) within 4 km of 76 composting facilities in England, as previously described (Williams et al., 2019). We fitted a hierarchical generalized mixed model to examine the risk of hospital admission with a primary diagnosis of (i) any respiratory condition, (ii) respiratory infections, (iii) asthma, (iv) COPD, (v) diseases due to organic dust, and (vi) Cystic Fibrosis, in relation to quartiles of Aspergillus fumigatus concentrations. Models included a random intercept for each COA to account for over-dispersion, nested within composting facility, on which a random intercept was fitted to account for clustering of the data, with adjustments for age, sex, ethnicity, deprivation, tobacco sales (smoking proxy) and traffic load (as a proxy for traffic-related air pollution). We included 249,748 respiratory-related and 3163 Cystic Fibrosis hospital admissions in 9606 COAs with a population-weighted centroid within 4 km of the 76 included composting facilities. After adjustment for confounders, no statistically significant effect was observed for any respiratory-related (Relative Risk (RR) = 0.99; 95% Confidence Interval (CI) 0.96-1.01) or for Cystic Fibrosis (RR = 1.01; 95% CI 0.56-1.83) hospital admissions for COAs in the highest quartile of exposure. Similar results were observed across all respiratory disease sub-groups. This study does not provide evidence for increased risks of respiratory-related hospitalisations for those living near composting facilities. However, given the limitations in the dispersion modelling, risks cannot be completely ruled out. Hospital admissions represent severe respiratory episodes, so further study would be needed to investigate whether bioaerosols emitted from composting facilities have impacts on less severe episodes or respiratory symptoms.

Risk of congenital anomalies near municipal waste incinerators in England and Scotland: Retrospective population-based cohort study.

BACKGROUND: Few studies have investigated congenital anomalies in relation to municipal waste incinerators (MWIs) and results are inconclusive. OBJECTIVES: To conduct a national investigation into the risk of congenital anomalies in babies born to mothers living within 10 km of an MWI associated with: i) modelled concentrations of PM10 as a proxy for MWI emissions more generally and; ii) proximity of residential postcode to nearest MWI, in areas in England and Scotland that are covered by a congenital anomaly register. METHODS: Retrospective population-based cohort study within 10 km of 10 MWIs in England and Scotland operating between 2003 and 2010. Exposure was proximity to MWI and log of daily mean modelled ground-level particulate matter ≤10 µm diameter (PM10) concentrations. RESULTS: Analysis included 219,486 births, stillbirths and terminations of pregnancy for fetal anomaly of which 5154 were cases of congenital anomalies. Fully adjusted odds ratio (OR) per doubling in PM10 was: 1·00 (95% CI 0·98-1·02) for all congenital anomalies; 0·99 (0·97-1·01) for all congenital anomalies excluding chromosomal anomalies. For every 1 km closer to an MWI adjusted OR was: 1·02 (1·00-1·04) for all congenital anomalies combined; 1·02 (1·00-1·04) for all congenital anomalies excluding chromosomal anomalies; and, for specific anomaly groups, 1·04 (1·01-1·08) for congenital heart defect sand 1·07 (1·02-1·12) for genital anomalies. DISCUSSION: We found no increased risk of congenital anomalies in relation to modelled PM10 emissions, but there were small excess risks associated with congenital heart defects and genital anomalies in proximity to MWIs. These latter findings may well reflect incomplete control for confounding, but a possible causal effect cannot be excluded.

Bioaerosol exposure from composting facilities and health outcomes in workers and in the community: A systematic review update.

BACKGROUND: Rapid population growth and urbanisation around the world has led to increasing waste generation rates. Composting of organic waste in large-scale facilities is part of a growing trend in the UK, and elsewhere, to better manage and re-use the organic waste. However, composting inevitably generates bioaerosols, which have been associated with human health effects. In 2015, we reported that there was some, albeit limited, qualitative evidence linking bioaerosol emissions from composting facilities to poor respiratory health in nearby residents. However, the limited evidence precluded any quantitative assessment. Since then, the number of operational industrial-scale composting facilities in England has increased by 9% - nearly twice the growth from 2012 to 2014. At the same time, rapid urbanisation has led to expansion of city borders with more people living near large composting facilities and exposed to bioaerosol pollution. It is essential that regulatory authorities have access to the most up to date and accurate information. OBJECTIVE: In this update of a systematic review published in 2015, we review and summarise the evidence from more recent studies that have assessed bioaerosol exposures within and near composting facilities and their associated health effects in both community and occupational health settings. Specifically, we wanted to find out if new evidence has emerged since the previous review to strengthen and confirm its conclusions. MATERIAL AND METHODS: Two electronic databases (Medline and Embase) and bibliographies were searched for studies reporting on health outcomes and/or exposure to bioaerosols from composting facilities published between 1 January 2014 and 15 June 2018. Identification of relevant articles and data extraction was undertaken and studies were assessed for risk of bias. RESULTS: 23 studies met the inclusion criteria (15 exposure studies, 4 health studies, 4 health and exposure studies (one of which used an exposure proxy)). The majority of studies were conducted in occupational settings, and over short time periods. Some progress has been made in the characterisation of bioaerosol emissions from these composting facilities, with the application of molecular-based methods. Whilst the latest health studies do not rely solely on subjective self-reported measures of health status but include more objective health measures, these studies were almost exclusively carried out in compost workers and were characterised by profound methodological limitations. Only one community health study was identified and used a proxy measure of bioaerosol exposure. CONCLUSIONS: Although this review identified an additional 23 studies since the earlier review, the conclusions remain largely unchanged. Given the absence of any consistent evidence on the toxicity of bioaerosols from composting facilities, there is insufficient evidence to provide a quantitative comment on the risk to nearby residents from exposure to compost bioaerosols. To improve risk assessment and to best advise on risk management, it is important to ensure that the research recommendations outlined in this review are addressed.

Fetal growth, stillbirth, infant mortality and other birth outcomes near UK municipal waste incinerators; retrospective population based cohort and case-control study.

BACKGROUND: Some studies have reported associations between municipal waste incinerator (MWI) exposures and adverse birth outcomes but there are few studies of modern MWIs operating to current European Union (EU) Industrial Emissions Directive standards. METHODS: Associations between modelled ground-level particulate matter ≤10 µm in diameter (PM10) from MWI emissions (as a proxy for MWI emissions) within 10 km of each MWI, and selected birth and infant mortality outcomes were examined for all 22 MWIs operating in Great Britain 2003-10. We also investigated associations with proximity of residence to a MWI. Outcomes used were term birth weight, small for gestational age (SGA) at term, stillbirth, neonatal, post-neonatal and infant mortality, multiple births, sex ratio and preterm delivery sourced from national registration data from the Office for National Statistics. Analyses were adjusted for relevant confounders including year of birth, sex, season of birth, maternal age, deprivation, ethnicity and area characteristics and random effect terms were included in the models to allow for differences in baseline rates between areas and in incinerator feedstock. RESULTS: Analyses included 1,025,064 births and 18,694 infant deaths. There was no excess risk in relation to any of the outcomes investigated during pregnancy or early life of either mean modelled MWI PM10 or proximity to an MWI. CONCLUSIONS: We found no evidence that exposure to PM10 from, or living near to, an MWI operating to current EU standards was associated with harm for any of the outcomes investigated. Results should be generalisable to other MWIs operating to similar standards.

A systematic review of the public health risks of bioaerosols from intensive farming.

BACKGROUND: Population growth, increasing food demands, and economic efficiency have been major driving forces behind farming intensification over recent decades. However, biological emissions (bioaerosols) from intensified livestock farming may have the potential to impact human health. Bioaerosols from intensive livestock farming have been reported to cause symptoms and/or illnesses in occupational-settings and there is concern about the potential health effects on people who live near the intensive farms. As well as adverse health effects, some potential beneficial effects have been attributed to farm exposures in early life. The aim of the study was to undertake a systematic review to evaluate potential for adverse health outcomes in populations living near intensive livestock farms. MATERIAL AND METHODS: Two electronic databases (PubMed and Scopus) and bibliographies were searched for studies reporting associations between health outcomes and bioaerosol emissions related to intensive farming published between January 1960 and April 2017, including both occupational and community studies. Two authors independently assessed studies for inclusion and extracted data. Risk of bias was assessed using a customized score. RESULTS: 38 health studies met the inclusion criteria (21 occupational and 1 community study measured bioaerosol concentrations, 16 community studies using a proxy measure for exposure). The majority of occupational studies found a negative impact on respiratory health outcomes and increases in inflammatory biomarkers among farm workers exposed to bioaerosols. Studies investigating the health of communities living near intensive farms had mixed findings. All four studies of asthma in children found increased reported asthma prevalence among children living or attending schools near an intensive farm. Papers principally investigated respiratory and immune system outcomes. CONCLUSIONS: The review indicated a potential impact of intensive farming on childhood respiratory health, based on a small number of studies using self-reported outcomes, but supported by findings from occupational studies. Further research is needed to measure and monitor exposure in community settings and relate this to objectively measured health outcomes.

Estimating Particulate Exposure from Modern Municipal Waste Incinerators in Great Britain.

Municipal Waste Incineration (MWI) is regulated through the European Union Directive on Industrial Emissions (IED), but there is ongoing public concern regarding potential hazards to health. Using dispersion modeling, we estimated spatial variability in PM10 concentrations arising from MWIs at postcodes (average 12 households) within 10 km of MWIs in Great Britain (GB) in 2003-2010. We also investigated change points in PM10 emissions in relation to introduction of EU Waste Incineration Directive (EU-WID) (subsequently transposed into IED) and correlations of PM10 with SO2, NOx, heavy metals, polychlorinated dibenzo-p-dioxins/furan (PCDD/F), polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions. Yearly average modeled PM10 concentrations were 1.00 × 10-5 to 5.53 × 10-2 µg m-3, a small contribution to ambient background levels which were typically 6.59-2.68 × 101 µg m-3, 3-5 orders of magnitude higher. While low, concentration surfaces are likely to represent a spatial proxy of other relevant pollutants. There were statistically significant correlations between PM10 and heavy metal compounds (other heavy metals (r = 0.43, p = <0.001)), PAHs (r = 0.20, p = 0.050), and PCBs (r = 0.19, p = 0.022). No clear change points were detected following EU-WID implementation, possibly as incinerators were operating to EU-WID standards before the implementation date. Results will be used in an epidemiological analysis examining potential associations between MWIs and health outcomes.

Emerging and legacy flame retardants in UK human milk and food suggest slow response to restrictions on use of PBDEs and HBCDD.

The legacy flame retardants (LFRs) polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD), together with six emerging flame retardants (EFRs) were measured in United Kingdom (UK) human milk collected in 2010 (n=25) and 2014-15 (n=10). These data are the first report of the presence of EFRs in UK human milk. The most abundant EFR was ß-tetrabromoethylcyclohexane (DBE-DBCH) (average=2.5ng/g lw; geometric mean=1.5ng/g lw), which is comparable to the concentrations of the most abundant LFRs i.e. BDE 47 and α-HBCDD at 2.8 and 2.1ng/g lw, respectively (geometric mean=2.1 and 1.7). The estimated median dietary intake of ΣEFRs by UK nursing infants was 18ng/kg bw/day. EFRs were also measured in UK foodstuffs with ß-DBE-DBCH again the predominant compound detected, accounting - on average - for 64.5±23.4% of ΣEFRs. Average estimated dietary intakes of ∑EFRs in the UK were 89 and 26ng/day (1.3 and 2.6ng/body weight/day) for adults and toddlers, respectively. Concentrations of Σtri-hexa BDEs in our UK food samples exceeded those reported in UK samples from the same food categories collected in 2003-04 and 2006. Despite this and our recent report elsewhere of significant temporal declines in concentrations of BDE 209 in UK indoor dust (p<0.05) and HBCDDs in UK indoor dust and air (p<0.001), no significant temporal differences (p>0.05) were observed between concentrations of Σtri-hexa BDEs, BDE 209 and HBCDDs in human milk sampled in 2010 and those obtained in 2014-15. UK adult body burdens for EFRs were predicted via inhalation, diet and dust ingestion using a simple pharmacokinetic model. The predicted EFR body burdens compared well with observed concentrations in human milk.

Predicting Aspergillus fumigatus exposure from composting facilities using a dispersion model: A conditional calibration and validation.

Bioaerosols are released in elevated quantities from composting facilities and are associated with negative health effects, although dose-response relationships are unclear. Exposure levels are difficult to quantify as established sampling methods are costly, time-consuming and current data provide limited temporal and spatial information. Confidence in dispersion model outputs in this context would be advantageous to provide a more detailed exposure assessment. We present the calibration and validation of a recognised atmospheric dispersion model (ADMS) for bioaerosol exposure assessments. The model was calibrated by a trial and error optimisation of observed Aspergillus fumigatus concentrations at different locations around a composting site. Validation was performed using a second dataset of measured concentrations for a different site. The best fit between modelled and measured data was achieved when emissions were represented as a single area source, with a temperature of 29°C. Predicted bioaerosol concentrations were within an order of magnitude of measured values (1000-10,000CFU/m3) at the validation site, once minor adjustments were made to reflect local differences between the sites (r2>0.7 at 150, 300, 500 and 600m downwind of source). Results suggest that calibrated dispersion modelling can be applied to make reasonable predictions of bioaerosol exposures at multiple sites and may be used to inform site regulation and operational management.

Respiratory hospital admission risk near large composting facilities.

BACKGROUND: Large-scale composting can release bioaerosols in elevated quantities, but there are few studies of health effects on nearby communities. METHODS: A cross-sectional ecological small area design was used to examine risk of respiratory hospital admissions within 2500m of all 148 English large-scale composting facilities in 2008-10. Statistical analyses used a random intercept Poisson regression model at Census Output Area (COA) level (mean population 310). Models were adjusted for age, sex, deprivation and tobacco sales. RESULTS: Analysing 34,963 respiratory hospital admissions in 4656 COAs within 250-2500m of a site, there were no significant trends using pre-defined distance bands of >250-750m, >750-1500m and >1500-2500m. Using a continuous measure of distance, there was a small non-statistically significant (p=0.054) association with total respiratory admissions corresponding to a 1.5% (95% CI: 0.0-2.9%) decrease in risk if moving from 251m to 501m. There were no significant associations for subgroups of respiratory infections, asthma or chronic obstructive pulmonary disease. CONCLUSION: This national study does not provide evidence for increased risks of respiratory hospital admissions in those living beyond 250m of an outdoor composting area perimeter. Further work using better measures of exposure and exploring associations with symptoms and disease prevalence, especially in vulnerable groups, is recommended to support regulatory approaches.

Exposures and health outcomes in relation to bioaerosol emissions from composting facilities: a systematic review of occupational and community studies.

The number of composting sites in Europe is rapidly increasing, due to efforts to reduce the fraction of waste destined for landfill, but evidence on possible health impacts is limited. This article systematically reviews studies related to bioaerosol exposures within and near composting facilities and associated health effects in both community and occupational health settings. Six electronic databases and bibliographies from January 1960 to July 2014 were searched for studies reporting on health outcomes and/or bioaerosol emissions related to composting sites. Risk of bias was assessed using a customized score. Five hundred and thirty-six papers were identified and reviewed, and 66 articles met the inclusion criteria (48 exposure studies, 9 health studies, 9 health and exposure studies). Exposure information was limited, with most measurements taken in occupational settings and for limited time periods. Bioaerosol concentrations were highest on-site during agitation activities (turning, shredding, and screening). Six studies detected concentrations of either Aspergillus fumigatus or total bacteria above the English Environment Agency's recommended threshold levels beyond 250 m from the site. Occupational studies of compost workers suggested elevated risks of respiratory illnesses with higher bioaerosol exposures. Elevated airway irritation was reported in residents near composting sites, but this may have been affected by reporting bias. The evidence base on health effects of bioaerosol emissions from composting facilities is still limited, although there is sufficient evidence to support a precautionary approach for regulatory purposes. While data to date are suggestive of possible respiratory effects, further study is needed to confirm this and to explore other health outcomes.