This scoping review will examine epidemiologic studies assessing associations between ambient air pollution exposure and neurodevelopmental disorder symptoms for three childhood neurodevelopmental disorders: ADHD, ASD, and OCD. It will also characterize the modifying roles of socioeconomic and neighbourhood characteristics.

This protocol has been registered with Open Science Foundation: .

Background

Neurodevelopmental disorders in children and adolescents

There is established evidence for the interaction between childhood neurodevelopmental disorders (NDDs) and genetic, social, and environmental factors (1ā€“5). Attention Deficit Hyperactivity Disorder (ADHD; prevalence 5-11%), Autism Spectrum Disorder (ASD; 1-3%), and Obsessive-Compulsive Disorder (OCD; 0.5-2%) are among the most common NDDs, affecting children and adolescents globally (6). Childhood NDDs are often co-occurrent with other NDDs (homotypic comorbidity) and with additional psychiatric pathologies (heterotypic comorbidity) such as anxiety and mood disorders (6).

Measuring the mental health burden in children and young people requires looking beyond clinical samples to dimensional symptom scores from population-based cohorts (7). Symptom rating scales implemented in community-based samples capture children who meet threshold criteria for an NDD but have not received a formal diagnosis given various healthcare disparities related to low income, race/ethnicity, etc. (8)

Note on OCD classification: In DSM-5, OCD is classified under “Obsessive-Compulsive and Related Disorders” rather than the Neurodevelopmental Disorders chapter. Its inclusion in this review is justified by its childhood onset, high co-occurrence with ADHD and ASD, and its established use as a neurodevelopmental outcome in the environmental epidemiology literature (5).

Environmental exposures and neurodevelopmental outcomes

Air pollution is a significant and increasing global risk factor for children and youth (9). Several ambient environmental exposures are associated with ADHD, ASD, and OCD incidence, acting as either risk or protective factors depending on exposure level and timing (10ā€“14). Prenatal and early-life PM2.5 exposure is reported in multiple cohort studies to raise ASD risk and impair cognitive development (11,15). NO2, a marker of traffic-related pollution, is linked to psychomotor delays and attention difficulties in children (13). Children with greater greenspace access score lower on NDD symptom measures including OCD, plausibly because greenspace reduces pollutant exposure, supports physical activity, and lowers physiological stress (14,16,17).

Most of this evidence concerns clinical diagnosis rather than dimensional symptom severity, with some exceptions (18,19). Prior systematic reviews and meta-analyses have predominantly treated ASD or ADHD diagnosis as a binary outcome, rather than examining scale scores that capture sub-threshold and severity variation (10). Most prior reviews have also been confined to a single NDD and a single exposure type, which limits understanding of multi-exposure effects and cross-diagnostic patterns. Clarifying how environmental exposures shape NDD trait severity, rather than diagnosis incidence, could directly inform community intervention priorities and strengthen the case for urban environmental standards protective of child neurodevelopment.

Rationale and justification for a scoping review

This review examines studies assessing associations between environmental exposures and NDD trait scores, and characterizes the modifying roles of social, neighbourhood, and genetic factors (20). Given the heterogeneity of NDD outcome measures, exposure types, and study designs in this area, a scoping review is more appropriate than a systematic review or meta-analysis. It maps evidence across multiple exposures and NDD outcomes without requiring pooling of effect estimates from incompatible measurement scales.

Prior meta-analyses have typically been restricted to a single exposure-outcome pair: Shang et al. (2020) for NO2 and psychomotor development; Lin et al. (2022) for particulate matter and NDDs; Alter et al. (2024) for PM2.5 and IQ (2ā€“4). The present review takes a broader mapping approach to characterize the breadth of measurement approaches across multiple exposures (environmental and social) and NDD types, and to identify evidence gaps and research priorities.

The format is also appropriate because the use of psychometric outcomes in environmental NDD research is still emerging. A scoping review lays the groundwork for subsequent systematic reviews with more precisely defined questions.

Prior reviews

Current systematic and scoping reviews in this area examine studies that measure only the incidence rate or clinical diagnosis of NDDs in relation to environmental exposures (2ā€“4,10ā€“12,21ā€“23). From an initial search of systematic and scoping reviews in December 2025, a search of PROSPERO, MEDLINE, the Cochrane Database of Systematic Reviews, and JBI Evidence Synthesis was conducted. No current or in-progress scoping reviews or systematic reviews were identified that specifically address trait scores and NDD symptoms for childhood NDDs in relation to multiple environmental and social exposures.

Gao et. al. (2025) conducted an umbrella review of environmental pollutant exposure and neurodevelopmental outcomes, including collection of assessment criteria or tools used (10). However, this review didnā€™t provide a discussion of included studies or the relationship between NDD symptoms and environmental exposures.

Numerous reviews have examined individual neurodevelopmental disorders or specific environmental exposures, but most focus on clinical incidence for a single NDD and do not address symptom severity or multi-morbidity. Prior reviews also rarely examine multiple environmental and social exposures and simultaneously. This review addresses both gaps.

Primary research question(s) 

The objective of this review is to map epidemiologic studies that assess the associations between ambient air pollution and neighbourhood environmental exposures (ambient air pollution and greenspace) and neurodevelopmental disorders (ADHD, ASD, and OCD) symptoms in children and adolescents, and to characterize the modifying roles of neighbourhood-level socioeconomic characteristics.

The following questions operationalize the review objective and guide the inclusion criteria and data extraction:

1. What validated ADHD, ASD, and OCD-related behavioural and/or cognitive measures have been used to (Concept) in children and adolescents aged 0-18 years (Population) exposed to ambient air pollution or greenspace, across any geographic setting (Context)?
2. What types of environmental exposures (PM2.5, PM10, NO2, O3, SO2, greenspace, and other ambient exposures) and what exposure measurement methods (ground monitoring, satellite-derived estimates, land-use regression, NDVI) have been employed in included studies?
3. 3) What socioeconomic and neighbourhood-level characteristics have been examined as potential modifiers of the exposure-NDD symptom score relationship?

Secondary research question(s) 

1. What exposure windows (prenatal, early childhood, school-age, cumulative) have been examined, and how have studies operationalized these windows?
2. What evidence gaps exist regarding multi-exposure designs, under-studied NDD types, and under-represented populations or geographic settings?

The post Protocol: Neurodevelopmental Disorder Symptoms In Children And Adolescents Exposed To Ambient Air Pollution: A Scoping Review Protocol appeared first on Determinants.

A National Epidemic with Severe Local Implications: A Global to Local Review of Substance Use to Analyze the State of Addictions in Rural Eastern Ontario

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A National Epidemic with Severe Local Implications

This research (summarized below) is also presented as an interactive ArcGIS Storymap available at the following link..

Substance Use in Canada

The dramatic rise in substance-use disorder prevalence across North America has become an urgent and escalating health issue in need of rapid intervention. In 2012, Statistics Canada conducted a study concluding that 6 million Canadians met the criteria for substance-use disorder, but even this value is thought to be an underestimate (1). It is likely this statistic has increased greatly since 2012 when considering the surging overdose crisis and significant increase in opioid-use, as well as opioid-related deaths in the past three years (2). In 2017, the cost of substance use was calculated to be $46 billion, a 5.4% increase since 2015, which factored for associated healthcare, lost productivity, criminal justice, and other direct costs (3). Substance use and addictions in Canada is therefore multifactorial, involving social, health, and economic implications.

Substance use and addiction is a global public health crisis that has rapidly escalated over the last decade. Substance use disorder is one of the most prevalent causes of morbidity and mortality internationally (4), with alcohol- and opioid-related harms being of most concern. The United States of America and Canada have historically had the highest prevalence of opioid drug use mostly due to the availability of such drugs when compared to less developed countries and have both seen an even greater increase in use since the emergence of Covid-19. Of greatest concern, is the spike in opioid deaths which has also more than doubled since 2010 (5). Canada and the United States have the highest rates of prescribed opioids worldwide, and although the US sees considerably more opioid-related deaths, per capita opioid use, and alcohol-attributed health deficits, recent data shows Canada is paralleling increases in these areas which is a cause of great concern (6). Continuing health professions education programs have begun to gain a hold on prescription opioids and their potentially harmful effects, but there has been a major increase in non-pharmaceutical opioid use across Canada which accounted for 90% of apparent opioid deaths from January to June 2021 (7).

The life expectancy of Canada has levelled for the first time since World War II, with one of the main contributors being opioid-related deaths. This negative trend was first observed in British Columbia, which has been in a declared public health emergency since 2016 due to significant opioid-related deaths, but life expectancy has since begun to plateau for all of Canada. Most deaths seen in the past five years have been males between the ages of 20-49, which therefore has a significant impact on life expectancy, with alcohol and drug use identified as the most important risk factor among young adults (7).

Alcohol and opioid use are currently a major focus for substance use disorder harms, as these sectors have seen the greatest increase in associated harms and affect the most individuals, although it should be noted that an increase in stimulant use as well as polysubstance use has been observed in the past few years. Substantially less mortality is seen with these substances, and toxic supply is less of a concern, but many of the initiatives and treatment options addressing the opioid crisis can also benefit those impacted by stimulant addiction and polysubstance use. Other addiction disorders such as gambling can also have detrimental effects on overall health and wellbeing of Canadians, but this report will have a greater focus on drug addiction and substance use disorder, specifically regarding opioid use, as it is an incredibly urgent public health crisis causing the death of thousands and therefore requires immediate intervention.

Our interactive ArcGIS Storymap provides further analysis of this epidemic for rural Eastern Ontario, highlighting both the harms and the services available in this region.

Link to the complete Storymap: .

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As a PhD student with mental health challenges, I sometimes question whether my experience is the same as my peers. Did they look for a supervisor who understands mental health?  Do they see themselves reflected in resources about ā€˜caring for your mental healthā€™ and ā€˜self-care for studentsā€™?

Donā€™t get me wrong, entering a PhD and being me has been remarkably rewarding. I have a supportive environment to explore my ideas, where my strange questions can lead to insightful conversations. Iā€™ve met peers who not only accept and encourage me but challenge my conceptualization of the world and my approach to research. I have a supervisor who sees value in my perspectives and believes in me. When applying to ŠÓ°ÉŌ­““, I was even exposed to . In essence, it feels like my potential in defining myself as an academic is limitless. While Iā€™m still waiting for this to come crashing down (Iā€™ve heard this happens in second year), I canā€™t help but think itā€™s the contrast between the supportive spaces Iā€™ve found and the concessions Iā€™ve had to make that makes my disappointment sting all the more.

At times, it can feel like the very institution of academia doesnā€™t accept me, and that even with acceptance, inclusion isnā€™t guaranteed and support is strictly rationed. For example, despite publishing an article on , ŠÓ°ÉŌ­““ā€™s counselling services arenā€™t set up to provide long-term support ā€“ which automatically necessitates that I seek support off campus. In order to pay for therapy, Iā€™ve had to label myself on provincial and school documentation as having a disability (regardless of whether I identify as that). While Iā€™m grateful for the support thatā€™s offered, the process of being forced into a label has sucked.

While writing this, the qualitative researcher in me couldnā€™t help but see the underlying theme in my experiences ā€“ the disconnect between the people and the system. My social and academic environments are ones of support and collaboration, where being me is a strength. How, then, have our institutional processes and policies not caught up?

These systemic barriers probably wonā€™t change anytime soon (or maybe they will, and Iā€™d be thrilled to be wrong here) but here are steps that prospective and current PhD students can take to protect or maintain their mental health based on my own experience:

Prospective students:

1. Include what you need (for your mental health) as a criterion in your search for the perfect supervisor or school.
2. Have open conversations with your potential supervisor about mental health. See if they are open to using different approaches to support you.
3. See if you can speak to a current graduate student about their experience. This can help you get a feel for the lab culture, and if it would be a supportive and inclusive environment.

New students:

1. Get registered with your university accessibility services as quickly as you can. Your disability coordinator can help you navigate OSAP and the NSLSC.
2. Think about moving your health information to Health Services on campus. This can be helpful for coordinating your services and setting up a comprehensive circle of care.
3. Pay attention to when bursaries open and close at your university. There are usually programs or bursaries that are specifically for helping people with disabilities.
4. See if you qualify for any of the awards .
5. Be open with your supervisor. Itā€™s not all sunshine and daisies and sometimes they can suggest strategies to help you cope.
6. Establish your support network prior to entering the program. Your supervisor isnā€™t your therapist, and it can be easy to cross boundaries and over-share if you donā€™t have solid supports in place prior to starting the program. Further, Iā€™ve found it hard to connect with peers if they donā€™t share similar life experiences and have relied on my friends more than ever.

The items in this list came from hours wading through blogs and Reddit treads (which, frankly, are often gloomy) and conversations with other folks who have been there, done that. As such, this isnā€™t a prescriptive list outlining the steps to success for PhD students with mental health concerns, but rather steps that have been helpful for me so far. I hope these lists might even slightly reduce the amount of labour necessary for our participation in academia. At the heart of it, I write this because, at the end of the day, we belong here.

Mel Edwards is a first year PhD Student in the Spatial Determinants of Health Lab. Her research interests include the use of e-mental health to support underserved populations in rural communities

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Waid C, Sinclair L, Priest L, Petrie S, Carson DB, Stevens S, & PA Peters (2019). Infographic: Rural Youth Mental Health Interventions. Spatial Determinants of Health Lab, ŠÓ°ÉŌ­““ University: Ottawa, ON. DOI:10.22215/sdhlab/kt/2019.2

A high-quality PDF of this infographic is available for download.

Estimates are that 20% of the world’s youth experience mental illness, leading to future disadvantages in family, finances, and employment. Youth residing in rural areas must travel long distances to access speciality health services such as mental health professionals – only to be met with longer wait times than urban counterparts.

Rural youth in Canada and Australia face similar inequities in accessibility of mental health services. When health services are not accessible, mental health care ends up becoming the responsibility of the community. But, communities are not trained in mental health care. The lack of robust rural and remote mental health care and the unique characteristics of each community leads to needs for community-based interventions.

We have created an infographic about barriers and facilitators for community-based interventions for rural youth mental health that we reviewed from the literature. Our hope is that this summary can provide a starting point for programs, policies, and research that addresses rural mental health services in rural and remote communities.

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Aboukarr S, LeBlanc M, Petrie S, Carson DB, Paskaran S, & PA Peters. (2019) Report: Best Practices for Rural eMental Health. Spatial Determinants of Health Lab, ŠÓ°ÉŌ­““ University: Ottawa, ON. DOI:10.22215/sdhlab/2019.2

A high-quality PDF of this report is available for download.

The more ā€œruralā€ or ā€œremoteā€ a community, access to mental health services decreases. By mitigating barriers and promoting enablers, successful eMental health integration can increase access to mental health services for rural residents.

eMental health aims to bridge the gap between rural and urban mental health services by introducing electronic methods such as teleconferencing or video conferencing for psychological services, virtual referral to psychiatrists, and sharing of electronic records. Successful integration of the technology remains a challenging task, with key actors, enablers, and barriers all influencing its success.

Rural patients and health care providers identify advantages and disadvantages in using eMental health. Health system users report increased access to care, decreased travel time, increased support, decreased hospital transfers, and stronger interpersonal relationships as advantages. Disadvantages include technical problems, privacy and confidentiality concerns, physical limitations, administrative difficulties, and inadequate health care provision.

Although patients and providers note these benefits or drawbacks based on their personal experiences, the success of an eMental health program may need to be reviewed on a larger scale. There is an association between modifiable systemic barriers and satisfaction levels, based on feedback from patients and providers. By focusing on the larger-scale enablers and barriers that underly the frustrations and successes that patients and providers experience using eMental health, disadvantages can be mitigated, and advantages can be amplified.

Primary systemic barriers to the success of telemedicine include inadequate technical equipment, funding/resource constraints, and resistance from health care providers, patients, and families. Enablers of the system include pre-established environment and care procedures, program promotion and training, regular contact among health care providers, technical improvements and support, organized administration, and planning procedures.

Technological issues often impede the successful uptake of eMental health in communities. Patients and providers report frustration with technology, including delayed speech and movement, sound echoes, and inadequate internet access. Rural areas that experience more technical problems report lower levels of utilization merely due to technological issues. If the infrastructure in which the technology operates is optimized, then the level of acceptance and integration of telemedicine into mental health services can be improved.

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