The 2019 Climate Change Act committed the UK to reducing its emissions of greenhouse gases to net zero by 2050. The 2019 UK Clean Air Strategy, sees "air pollution as one of the UK's biggest public health challenges", aims to secure clean growth whilst tackling air pollution through reducing emissions. Achieving these reductions in greenhouse gas and air pollutant emissions will entail substantial reductions in use of fossil fuels and changes to the transport fleet over coming years as we make the transition to a 'low carbon economy'. This will also have an important benefit for health of improving levels of outdoor air pollution by reducing emissions from power plants, motor vehicles, wood/coal burning at home and other sources.

However, another important climate change action is to improve energy efficiency in homes. Those measures typically entail reducing levels of ventilation to cut down heat losses from escape of heated air. In addition to helping improve winter indoor temperatures, this can be beneficial for human health because it reduces the penetration into the home of air pollutants from the outdoor environment. But it will increase indoor levels of air pollutants derived from sources inside the home - such as particles and gases generated by cooking, volatile organic compounds (VOCs) given off from fabrics and furnishings, cleaning and personal care products.

The changes to indoor pollution levels from improved home energy efficiency may thus be overall positive or negative for the health of building occupants depending on the balance of effects on pollutants entering and leaving the indoor environment. That balance is likely to depend on the levels of outdoor pollutants, indoor air pollutant sources and activities that generate these, the form of the energy efficiency improvements, the behaviour of occupants and their vulnerability to air pollutants. People at particular risk are young children, the elderly, those with pre-existing illnesses, and those experiencing social deprivation.

To improve understanding of these issues, we have created a new research network (acronym 'HEICCAAM'). This network brings together experienced and early career researchers from nine universities from disciplines as diverse as air quality measurement and modelling, building physics, behavioural science, health and health inequalities, education and policy. The network will also include representatives of the public, as well as stakeholders from the public sector, business/industry and non-government bodies - including Public Health England, Health Protection and NHS Scotland, Scottish Environment Protection Agency, Age UK, the Passivhaus Trust, Good Homes Alliance, Edinburgh City Council, the Chartered Institution of Building Services Engineers and the UK Met Office.

The network will build evidence on the consequences for exposure to air pollution of actions aimed at tackling climate change and poor air quality, with particular focus on the home environment. Its aim is to provide underpinning research that can inform and influence policy and practice to safeguard human health. The network will include activities by six Working Groups tasked with generating a series of papers on relevant issues of science and policy. It will also undertake four small research projects aimed at improving understanding of key issues where there are knowledge gaps. It will have a particular focus on protecting the health of vulnerable groups and reduction of health inequities. Network members will have multiple interactions through electronic meetings, webinars, discussion groups and an annual meeting and workshop with a wider group of stakeholders.

Through its activities, the network will help build long-term capability in interdisciplinary research in this area, including through the interactions with early career researchers, the development of new research plans, and linkage to other networks and existing research programmes.

Potential Impact:
Who will benefit? Our network has 18 project partners stakeholders across the public sector, business/industry and the third sector that will ensure policy and industry relevance and impact. UK policy makers and regulatory agencies will benefit from the proposed research and policy recommendations into the air-pollution related health effects of home energy efficiency measures: the Department for Business, Energy & Industrial Strategy (BEIS), the Department of the Environment, Food and Rural Affairs (DEFRA) and the Ministry of Housing, Communities and Local Government (HCLG) who are particularly involved in Climate Change Mitigation and Building Regulations. Our network findings will also benefit local councils and authorities such as the Scottish Environment Protection Agency (SEPA), and the UK Met Office.

Ultimately our findings will benefit to UK Department of Health (DH), Public Health England (PHE), Health Protection Scotland (HPS) and NHS Health Scotland whose remit is to protect and improve the nation's health and wellbeing. PHE, PHS and NHS Health Scotland are part of our network. International policy makers and air quality assessment bodies, especially the World Health Organization (WHO), IPCC, the World Meteorological Organization (WMO), will also benefit, as will other organisations interested in air climate change mitigation and health. The findings will also interest health advocacy agencies, e.g. Joseph Rowntree Foundation (JRF) and the Equality Trust, as well as government agencies and local authorities around the UK. Industry, e.g. companies that develop sensors and housing developers will benefit as will charities concerned with health and housing including, Age UK, Chartered Institution of Building Services Engineers, Passivhaus Trust, Good Homes Alliance, Housing Learning and Improvement Network (LIN) will similarly benefit. The UK population would directly benefit from any positive change in indoor air quality.

How will they benefit? We will build on existing links with members of the UK regulatory agencies that inform and shape UK air quality and climate change, environment and housing policy (e.g. DEFRA, DH, BEIS, HCLG), who will be invited to our final dissemination event, and benefit from our policy recommendations. Our research and co-produced policy recommendations will particularly benefit SEPA who have a role to deliver the Clean Air for Scotland Strategy and PHE who have just issued the first ever indoor air quality guidelines for the UK. The Met Office will benefit from insights into how their modelling of scenarios for air quality and climate mitigation can be linked to indoor exposure and to health risks.

Moreover, our co-produced network findings on how to reduce air pollution-related health risks indoors, and how these vary with vulnerable groups and behaviour will benefit DH, PHE, HPS and NHS Health Scotland in their future strategies to improve public health and reduce inequalities. Industry, through companies that develop air pollution measurement including sensor capabilities and the home developers, will benefit from our findings on senor technologies for indoor air quality monitoring, and implications related to building ventilation/insulation. Our network partners concerned with housing and health (charities: Age UK, the Chartered Institution of Building Services Engineers, Passivhaus Trust, Good Homes Alliance, LIN and local authorities such as Edinburgh/Norwich City Councils) will co-produce input into new recommendations on building design measures/regulations.

International policy assessment bodies (e.g. WHO, WMO) will benefit from findings on health impacts and socio-economic variations associated with air quality and climate change policies. The focus on vulnerable groups will provide a clearer knowledge base to implement the recent Marmot Review. The wider public will benefit from potential new interventions to improve energy efficiency and air quality.