Importance and need Ambient air pollution (AAP) causes 4.2 million premature deaths globally each year. It is a major contributor to non-communicable diseases, second only to cigarette smoking. In early-life, exposure to AAP influences the long-term risk of chronic disease development. Many diseases associated with AAP, such as respiratory illnesses , originate in childhood. Poor and ethnic minority children are disproportionately affected by AAP . Effective and equitable policy interventions targeting children are thus crucial. As a vulnerable group unable to control their exposures, children need to be considered and protected in policy transitions to clean air and net-zero.
Advancing current understandings and practice To tackle the inequitable health burden of AAP, we need to advance our understanding of where early-life exposures occur and how different children may be exposed differently and/or respond differently to the same exposures. This advanced understanding needs to be incorporated into decision-support tools, most notably health impact assessments (HIA), which can then assess equity impacts of clean air and net-zero transitions. I propose building a holistic program centred on the integration of multidisciplinary data, methods, tools, and networks. This integration will enable me to innovatively capture childhood exposure to AAP, estimate novel associations with chronic disease development, create and implement an equity oriented HIA, and foster enduring strategic coalitions and partnerships. The innovation in the exposure assessment can uncover fundamental insights into exposure disparities and health effects of AAP. The equity oriented HIA tool can have transformative impact on practice and policymaking. And creating a nucleus of diverse and engaged stakeholders can amplify the program’s impact. My approach will pave the way for addressing other complex and inequitable environmental health challenges.
Timeliness and trends I have been researching AAP and its health effects, primarily in children, over the past decade. The challenge of AAP is enduring. Whilst overall AAP levels have declined in some countries including the UK, levels are still considered too high to protect human health remaining above World Health Organisation (WHO) guidelines. Net-zero policies, such vehicles electrification, are expected to reduce AAP. However, these reductions will not be enough; tempered by a large, projected increase in future demand for transport leading to potential increases in non-exhaust emissions .
General AAP reductions also mask environmental injustice where there has been no progress in reducing the exposure gap between socioeconomic and racial groups . In the UK, the exposure gap between the poor and rich even increased in what has been cited as a failure of UK air quality policy . This failure is evident at locations important for children’s health. UK schools with high annual particulate matter less than 2.5 micrometres in diameter (PM2.5) levels (>12 μgm-3) had a significantly higher intake of pupils on free school meals (17.8%) and ethnic minorities (78.3%) compared to schools with low PM2.5 (<6 μgm-3, 6.5% on free school and 6.8% ethnic minorities) . Children spend about 30% of their time in schools . Commuting to school is another major contributor to exposure that is understudied. For example, AAP during commuting was 52% higher than exposures at school on average . Commuting mode and routes dictate exposures and vary between socioeconomic and racial groups complicating the understanding of equity impacts of e.g., transport policies targeting travel to school.
There is also sporadic evidence that the most exposed children might respond differently to their AAP exposures. This can be due to higher individual susceptibility or complex interactions with environmental, lifestyle and social characteristics. For example, despite controlling for a comprehensive set of confounders, I consistently observed larger associations between AAP and asthma and wheeze in children from families who struggled financially and children from Pakistani origins in Bradford, UK. So far, I do not have a satisfactory explanation of such differences but an indication of slightly higher exposure variability in the Pakistani but not the financially strained children. The question as to whether certain children respond differently to their exposures remains challenging to answer via traditional epidemiological studies which predominantly rely on a naïve assessment of exposure at the residential address only. Such studies are the norm and incapable of accurately representing exposure variability.
Impact Advancing current understandings of where exposures occur, how exposures vary across different children, and how different children might react differently to AAP has significant implications for policymaking. It can pinpoint which environments policies need to target to be most effective (e.g., at schools, on the route to school) and reveal any differential impact of policies on subgroups who may need more prioritization through a stratified approach to prevention (e.g., ethnic minorities).
But advancing understandings without a holistic approach to drive impact will not be enough. New knowledge needs translation into a new generation of equity oriented HIA, a key aspect of my program. I will use the HIA to test various clean air and net-zero policies solicited from and designed with stakeholders, focusing on climate policies which represent pathways in motion that can reduce both pollutant and greenhouse gas emissions. This focus strategically aligns with current national and global agendas on, and large investments in, net-zero and can reorient policy to better reduce inequities. As equity is also political and multi-sectoral, I acknowledge that my vision of reducing inequity extends well beyond the provision of new scientific information or adept decision-support tools. Actively engaging with policymakers and clustering influential partners to champion children’s health, prioritize equity and uptake novel science and tools is essential and at the heart of my program.