Research and analysis

Environmental Public Health Surveillance System (EPHSS) report for 2021 to 2023

Updated 29 May 2025

Executive summary

Environmental factors are a leading cause of non-communicable diseases, they can impact the effect and transmission of infectious diseases and can have wide-reaching social and economic impacts. The UK Health Security Agency (UKHSA) has developed a web-based surveillance system for environmental exposures called the Environmental Public Health Surveillance System (EPHSS). It is an information tool that supports surveillance and monitoring of environmental risk factors for health.

EPHSS was launched in the summer of 2020 and is currently being used internally by UKHSA staff. It contains 4 modules:

1. Environmental Events Surveillance
2. Lead Exposure in Children Surveillance System
3. Met Office Data Interface
4. Food Contamination module

The Met Office Data Interface module is planned to be available to external users in late 2024 and additional interfaces will be developed with other data systems in the future.

This summary surveillance report provides an update on the Environmental Public Health Surveillance System and summarises data contained within the system from 2021 to 2023 inclusive. It follows on from the first report, published in 2022, which introduced the surveillance system, demonstrated the data flows in EPHSS and showcased its functions.

1. Environmental Events Surveillance

This module provides surveillance of environmental events and incidents with the potential to impact health, occurring from 1 January 2015 onwards, affecting the population in England. Organisations will be able to use this module to feed in data on environmental events and incidents and produce surveillance reports on the data. Currently data is imported from UKHSA’s Chemical Incident Response and Information System (CIRIS) on environmental events and incidents occurring in England. This system is used for incident management by UKHSA’s Environmental Hazards and Emergencies Department.

There were between 700 and 1,100 environmental incidents per year in England between 2021 and 2023 inclusive. There was a sharp drop in incidents in 2021 which could have been due to the impact of the COVID-19 pandemic. London was the region which reported the most incidents annually, followed by the West Midlands. The most common incident type was fire, and the most common setting for incidents was within households. The most common agents involved in incidents were lead and carbon monoxide, though both of these are subject to active surveillance and public health follow-up.

2. Lead Exposure in Children Surveillance System (LEICSS)

Lead Exposure in Children Surveillance System (LEICSS) is a sentinel, passive, laboratory-based surveillance system. Cases are defined as children less than 16 years and resident in England with a blood lead concentration of greater than or equal to 0.24 micromoles per liter (μmol/L) (greater than or equal to 5 microgram per decilitre (μg/dL)), with surveillance data available from 2014 onwards. The LEICSS module within EPHSS can be interrogated to produce reports on the number of cases, demographics and blood lead concentrations recorded over different time periods.

Between the 1 January 2021 and the 31 December 2023, there were 543 lead exposure cases in children in England, with 78% reported to LEICSS directly from laboratories.

Annually between 2021 and 2023, there were between 126 and 234 cases reported across England. This is an increase on the annual count of between 33 and 50 lead exposure cases between 2015 to 2020 and reflects the case definition change in July 2021.

A comprehensive surveillance report is produced and published annually by the LEICSS working group.

3. Met Office Data Interface

The Met Office Data Interface (MODI) allows access to the Meteorological (Met) Office Integrated Data Archive System (MIDAS) data sets which are derived from observational records, measured and quality-controlled from hundreds of weather stations in the UK. This data stream has been built to provide data for the public health community. MIDAS covers all of the UK. Data can be prepared by single point site (that is, latitude and longitude coordinates), multiple point sites or rectangular grid area. Indicators can be processed over time at point sites, or at a given time over a grid area. Data includes multiple meteorological variables, for example temperature, rainfall, wind speed, and pollen count.

The MODI module of EPHSS will become accessible to external users in 2025.

4. Food Contamination

This module went live in 2021 and provides information and links to data on food contamination for use by UKHSA staff in managing risks to public health and for surveillance purposes. This includes links to the Food Standards Agency (FSA) public data catalogues, listing datasets on chemical contaminant incidents in food in England and Wales, hosts a copy of a private data catalogue held by FSA, information on the food safety system, emerging food and safety risks (Food Signals Dashboard), and issues that are being considered as part of the food and animal feed risk analysis process (Risk Likelihood Dashboard). A new link to the FSA’s ‘Register of Risk Analysis Issues’ was added in 2024.

More information on EPHSS can be found at Environmental public health surveillance system or by emailing ephss@ukhsa.gov.uk

Background

Environmental public health tracking

Environmental factors are a leading cause of non-communicable diseases (NCDs) and impact the effect and transmission of infectious diseases. Surveillance of environmental hazards and exposures is a crucial step towards understanding the burden of acute and chronic environmental effects on health.

UKHSA’s Environmental Public Health Tracking (EPHT) programme has led the development of a web-based surveillance system for environmental exposures called the Environmental Public Health Surveillance System (EPHSS). EPHSS launched in the summer of 2020 to Public Health England (PHE) (now UKHSA) internal staff and has been continually developed with additional modules, functionalities and data. EPHSS will be available to external users later in 2025.

The work of the EPHT programme and EPHSS is delivered by the Environmental Epidemiology Team. More information is available at Environmental public health tracking.

Purpose of this report

This is the second report on EPHSS following the first report published in March 2022 which covered data for the years 2020 to 2021.

This report has 2 aims:

1. To showcase the EPHSS surveillance system, its development and its functions.
2. To summarise surveillance data collated in EPHSS to date and to inform action.

System description

Environmental Public Health Surveillance System

EPHSS aims to provide a comprehensive surveillance capability that allows the public health community to interrogate data and intelligence gathered on environmental hazards, exposures, and related health outcomes from a variety of data sources. It is an information tool that supports surveillance and monitoring of environmental risk factors.

This system has been developed by UKHSA’s Environmental Public Health Tracking (EPHT) programme led by the Environmental Epidemiology Team (EET) in the Radiation, Chemical and Environmental Hazards Directorate (RCE). This is governed by the EPHT programme board. It has been developed in partnership with the Software Development Unit, now the Data, Analytics and Surveillance group, with collaboration from UKHSA Centres and Regions, Field Services, Geographic Information Systems (GIS) team, and ICT department.

EPHSS modules and structure

EPHSS delivers a modular system. Data linkages with several operational databases provide a surveillance function on different aspects of environmental public health. Additional interfaces with other target systems for enhanced data capture from other partnering agencies are planned in the future.

The current version of EPHSS contains 4 modules (Figure 1).

Figure 1. EPHSS modular structure

1. Environmental Events Surveillance

Case definition and population

The Environmental Events Surveillance (EES) module includes information on environmental events and incidents with the potential to impact health, occurring from 1 January 2015 onwards, affecting the population in England.

Data is available at individual event level and also aggregated at UKHSA centre, health protection team (HPT) region, and upper and lower tier local authority levels.

Description

The aim of this module is to provide surveillance of environmental events or incidents that have the potential to impact on public health. The module has the capability to capture information about acute or chronic environmental events and incidents from several sources and link these together.

Information about environmental events and incidents (acute and chronic) is captured from several sources. This information is collected primarily for incident management use. At present, most data is provided by daily bulk uploads from UKHSA RCE’s Environmental Hazards and Emergencies Department’s (EHED) Chemical Incident Response and Information System (CIRIS). This is an incident management system used to capture and manage events and incidents that UKHSA is notified of to provide public health input and advice. Incident management records for acute and chronic exposures, including chemical exposures and extreme weather including flooding and heatwaves, are logged on CIRIS and an extract is automatically uploaded into EPHSS for surveillance purposes.

Headline information on these events are imported into EPHSS daily so that data can be queried, and several different surveillance reports generated.

The environmental events module receives data updates overnight and data is up to date as of the last 24 hours.

Recent developments

Quality data assurance is underway, with the EET undertaking work to check the quality of the data included in the EES, filtering out non-events, and checking sensitivity and visibility of events for users.

The system is being prepared to have the functionality of accepting external organisations data, so that a more complete picture of environmental events and incidents is represented by surveillance reports.

CIRIS will be replaced with a new system called Environmental Public Health Incident/Enquiry Database (EPHID) in autumn 2025 and this will provide the data to the EES module.

Summary of environmental incidents data, occurring in 2021 to 2023

Incidents per region per year

Between 700 and 1,100 incidents of all types were reported in England per year from 2021 to 2023 inclusive (Figure 2). Data has been included from 2015 to 2020 to allow for the observation of trends over time. Overall incidents increased between 2021 and 2023 but are lower than in 2020. The sharp drop in incidents between 2020 and 2021 may have been due to the impact of the COVID-19 pandemic, where periods of lockdown restricted population movement. Prior to 2021, incident reporting increased from 2016 to 2020. London consistently reported the greatest number of annual incidents from 2015 to 2023 followed by the West Midlands, and the lowest number was consistently reported in the North East (Figure 3).

Figure 2. Environmental incidents recorded per year 2015 to 2023 in England (data has been updated since the last Summary Surveillance Report 2020 to 2021)

Figure 3. Environmental incidents recorded per year 2015 to 2023 by UKHSA centre in England

Figure 4 shows the number of incidents per upper-tier local authority (UTLA) in 2023. Most incidents occurred in Surrey and Birmingham UTLAs (22 to 31 incidents per UTLA in 2023). The number of incidents has not been adjusted for population size.

Figure 4. EPHSS-generated map showing incidents by UTLAs in 2023, unadjusted by population size

Types of incidents per year

Incidents are described by type, as classified for incident management purposes. The most common incident type is fire, contributing to 33% of incidents over the 3-year period (Table 1). Between 2015 to 2020, Fire was also the most common incident type, contributing to 31% of incidents. Note, one event may have more than one type of incident assigned to it so the total columns are for all incidents, not just the most common incident types shown.

Setting of incidents per year

The most common setting for incidents was households (43%) (see Table 2). Whilst the order of the 5 most common settings for incidents is unchanged, the proportion in a house or flat has increased from the period 2015 to 2020. Note that not all events had a location described and some events may have more than one location type. The total columns are for all incidents, not just the most common incident locations shown.

Table 1. Five most common incident types reported per year in England 2015 to 2023 (totals are for all incidents in time periods)

Incident	2015	2016	2017	2018	2019	2020	All incidents 2015 to 2020 Total (number)	All incidents 2015 to 2020 total (percentage)	2021	2022	2023	All incidents 2021 to 2023 total (number)	All incidents 2021 to 2023 total (percentage)
Fire	359	258	289	372	394	606	2,278	31	322	430	375	1,127	33
Airborne	245	195	186	211	179	206	1,222	16	121	146	256	523	15
Person	128	123	135	185	154	207	932	12	131	183	259	573	17
Indoor air	114	107	91	122	108	143	685	9	78	93	171	342	10
Drinking water	110	127	112	83	110	96	638	9	56	89	111	256	7
Total	1,282	1,087	1,102	1,258	1,196	1,532	7,457		867	1,110	1,475	3,452

Table 2. Five most common location types reported per year in England 2015 to 2023

Location	2015	2016	2017	2018	2019	2020	All locations 2015 to 2020 total (number)	All locations 2015 to 2020 total (percentage)	2021	2022	2023	All locations 2021 to 2023 total (number)	All locations 2021 to 2023 total (percentage)
House or flat	313	291	317	340	344	481	2,086	35	269	311	474	1,054	43
Factory	148	83	68	79	92	87	557	9	53	57	58	168	7
Waste processing site	62	77	60	61	59	98	417	7	53	69	54	176	7
Agricultural	60	36	50	58	67	97	368	6	48	60	59	167	7
Warehouse	53	46	30	52	36	64	281	5	33	32	28	93	4
Total	1,071	878	879	977	974	1,216	5,995		662	800	1,015	2,477

Agent types

Agent types are recorded using the REACH classification, which stands for Registration, Evaluation, Authorisation and Restriction of Chemicals regulation. Read more at Rationale for prioritising substances in the UK REACH work programme: 2023 to 2024. This data can be downloaded both from the basic surveillance and from the customised surveillance reports.

Between 2015 and 2020, there were 2,623 chemical incidents reported (Table 3) and between 2021 and 2023, there were 1,155 chemical incidents reported (Table 4), involving 182 different chemical agents. One incident may involve more than one agent. The most common chemical agents between 2021 and 2023 were lead and carbon monoxide, though these agents are under active surveillance and more likely to be recorded. Other most common agents now involved chlorine, methane and natural gas.

Table 3. Number of incidents 2015 to 2020 inclusive related to the 5 most common agent types

Agent type	Incidents (number)	Incidents (percentage)
Lead	349	13
Carbon monoxide	256	10
Chlorine	136	5
Mercury	89	3
Ammonia, anhydrous	58	2
Total	2,623	100

Table 4. Number of incidents 2021 to 2023 inclusive related to the 5 most common agent types

Agent type	Incidents (number)	Incidents (percentage)
Lead	255	22
Carbon monoxide	140	12
Chlorine	73	6
Methane	28	2
Natural gas	26	2
Total	1,155	100

Example data: airborne exposures in the London region of England in 2023

EPHSS functionalities allow more detailed investigations into individual incident types and specific geographies. In the following examples we consider airborne exposures in 2023 in the London region of England, with the geography described by the London UKHSA Centre. The areas described by UKHSA centres and by health protection teams (HPTs) have changed over time due to boundary changes, so results may include data for locations which are no longer in those areas.

Under the Incidents tab, incidents can be searched in the EPHSS database using Dates, Incident Type, Location Type and Geography (local authority) as filters to narrow the search. Results cannot be exported or saved from this direct search, but EPHSS has different report formats with different levels of detail which allow the user to export the data using these functionalities:

• CIRIS report: provides summary data on types of incidents by UKHSA centre
• surveillance report – basic report: generates bar or pie charts of surveillance data, including incident type, location and route of exposure amongst other fields
• surveillance report – customised report: allows users to produce bespoke queries on the data to produce summary statistics or line lists that can be downloaded for further analysis

There are also maps which allow the user to display overall number of incidents by UTLA (area statistics map) or by location (point incident map). Examples follow below.

CIRIS report

A CIRIS report displays a bar chart for incident types by UKHSA centre and the health protection teams in that area. In the London UKHSA centre between 1 January 2021 and 31 December 2023, ‘airborne’ was the most common incident and the majority of these occurred in the North East and North Central London HPT area (now North London HPT) (Figure 5). The report also displays a table of the number of incidents by different chemical agents, and a table for the number of incidents by other agents (data now shown here).

Figure 5. EPHSS-generated bar chart showing number of incidents by type and HPT in the London UKHSA centres 2021 to 2023

Basic surveillance report

A basic surveillance report generates bar or pie charts of the surveillance data, and the report data can be downloaded as an Excel file. Other file formats are available for download, including PDF. A report was run for incident type in London between 1 January 2021 to 31 December 2023 inclusive. Fire (245) and airborne incidents (206) were the most common incident types in London (see Figure 6).

Figure 6. EPHSS-generated bar chart showing incident types in the London UKHSA centre in 2021 to 2023

The report was rerun to only show incidents in London Borough of Lambeth upper-tier local authority (UTLA) for example. As expected, there are fewer incidents overall, but now indoor air incidents (8) are the more common type (see Figure 7). Most incidents were in a house or flat, which reflects that Lambeth is a densely populated urban location.

Figure 7. EPHSS-generated bar chart showing incident types and locations in Lambeth in 2021 to 2023

Customised surveillance report

A customised surveillance report generates a line list of incidents. This is available in different formats depending on whether its purpose is for analysis or for viewing individual records.

A report was run on airborne incident type using the customised line listing reporting facility for analysis in the London Borough of Lambeth Upper Tier Local Authority in the London UKHSA Centre between 1 January 2023 and 31 December 2023. There were 116 airborne incidents in London during this time, of which 3 were in Lambeth as shown in Table 5.

Table 5. EPHSS-generated line list of airborne incidents in Lambeth 2023, showing date, incident description, action taken and responding organisation

Date	Description	Reporting organisation	UTLA	LTLA	Action taken	Responding organisation
24 May 2023	Gas leak, Vauxhall, London	Public Health England	Lambeth	Lambeth	- area ventilated - environmental monitoring and modelling - evacuation	- Ambulance Service (from CIRIS) - Fire and Rescue Service (from CIRIS) - other - water, gas, electric company
8 September 2023	15 pump fire at solid waste transfer station, Herne Hill, London	UK Health Security Agency	Lambeth	Lambeth	- environmental monitoring and modelling - fire fighting - sheltering in place	- all local authority (from CIRIS) - Ambulance Service (from CIRIS) - Environment Agency (from CIRIS) - Fire and Rescue Service (from CIRIS) - other - police (from CIRIS)
25 October 2023	Incorrect mixing of household cleaning products, Lambeth, London	UK Health Security Agency	Lambeth			- Ambulance Service (from CIRIS) - Fire and Rescue Service (from CIRIS) - other

2. Lead Exposure Surveillance

Case definition and population

Since 5 July 2021, the case definition captured by the Lead Exposure in Children Surveillance System (LEICSS) in EPHSS is:

• a child aged under 16 years
• resident in England
• with a blood lead concentration greater than or equal to 0.24 µmol/l (greater than or equal to 5 µg/dL) as detected in a UK Accreditation Service (UKAS) accredited biochemistry or toxicology laboratory
• reported to UKHSA for public health interventions

The case definition changed in July 2021 – see the recent developments section for further information.

Description

EPHSS delivers LEICSS as a separate module. A separate comprehensive surveillance report is published annually by the LEICSS working group available here.

LEICSS is a sentinel, passive, laboratory-based surveillance system. Clinical biochemical trace element laboratories in England report cases of lead exposure in children that meet the case definition to UKHSA directly. Most cases are asymptomatic and are identified opportunistically. Cases are logged onto the system and the local HPTs are notified of cases using UKHSA’s HPZone/CIMS which is a case and incident management system used by HPTs. HPTs manage the public health interventions by liaising with clinicians, parents, UKHSA RCE, local authority environmental health officers, social services and/or housing services. For surveillance purposes, additional case reports are also found via a systematic search of HPZone/CIMS.

The LEICSS module in EPHSS can be interrogated to produce reports on the number of cases, demographics, and blood lead concentrations recorded over different time periods.

Recent developments

The blood lead concentration is referred to the ‘public health intervention’ at which action is recommended. In July 2021 the public health intervention was lowered from greater than 10 μg/dL (greater than 0.48 μmol/L) for children aged under 16 years to greater than 0.24 µmol/l (greater than 5 µg/dL).

The system and case definition changed to incorporate reporting at the lower level.

Summary of lead exposures in children reported in 2021 to 2023 inclusive

Lead exposure cases per year

Between the 1 January 2021 and the 31 December 2023, there were 543 lead exposure cases in children in England, with 78% reported to LEICSS directly from laboratories. Annually between 2021 and 2023, there were between 126 and 234 cases across England. This is an increase on the annual count of between 33 and 50 lead exposure cases between 2015 to 2020 and reflects the case definition change in July 2021 and also better case ascertainment through laboratory reporting and improved awareness of the surveillance.

Lead exposures by UKHSA centre

Figure 8 shows the number of lead exposure cases for children aged 0 to 16 years by UKHSA centres reported during 2021 to 2023 inclusive. Yorkshire and Humber UKHSA Region were notified of the most cases (199 cases). There is a lab testing system in this area which proactively prompts clinicians to consider testing blood lead concentration for children with pica and iron deficiency.

The average reporting rate of cases per million children per year between 2021 and 2023 ranged from 1.5 in the North East to 19 in Yorkshire and Humber.

Figure 8. EPHSS-generated map showing lead exposures by UKHSA centre, 2021 to 2023

Lead exposures by age and gender

Between 2021 and 2023 inclusive, there were more lead exposures in males than in females (65% versus 35%). The was true in all age groups up to 12 years old, and the relative difference is more pronounced among children aged 1 to 4 (Figure 9).

Figure 9. EPHSS-generated age-gender pyramid of cases of lead exposure in children reported in England from 1 January 2021 to 31 December 2023

For more information on LEICSS and cases, see the most recent LEICSS annual report published in 2023, Lead exposure in children: surveillance reports from 2021.

3. Met Office Dataset Interface

Description

Weather conditions affect public health in many different ways. Extreme weather events can lead to short- and long-term adverse health outcomes, and climate change is affecting the distribution of vector-borne diseases and the frequency of extreme weather. EPHSS’s Met Office Dataset Interface (MODI) allows access to meteorological data which can then be linked to health data to investigate these effects. This data stream has been built to provide data for the public health community.

MODI provides access to Met Office Integrated Data Archive System (MIDAS). MIDAS data sets are derived from observational records, measured and quality-controlled from hundreds of weather stations in the UK. Data includes multiple meteorological variables, for example temperature, rainfall, wind speed, and pollen count. The data is updated daily and can be retrieved through a user friendly data request form on the web based EPHSS portal.

Data can be obtained in a time series format for a specific location, or as a single snapshot in time for a gridded area. Spatial-temporal processing of data (such as interpolation or downscaling) is available. It is also possible to download raw station data. The data is made available in spreadsheet (comma-separated values or CSV) format.

MIDAS data sets were previously held on Medical Environmental Data Mash-up Infrastructure (MEDMI) servers. The MEDMI project explored different ways to link and interrogate databases and lay the foundation for a shared resource for medical, environmental and public health researchers in the UK. See MEDMI – Connecting health and environment data.

By bringing together several complex data sets, MEDMI aimed to improve research into the links between climate, weather, the environment and health. The MEDMI servers were retired on 1 July 2023 and external existing users will be moved onto the EPHSS system for access once external access to EPHSS becomes available later in 2025.

As an interim solution, external users can request data from the EPHSS team, with the requests being fulfilled by UKHSA staff by emailing ephss@ukhsa.gov.uk

Recent developments

These include:

• a user help document has been produced to help users in defining better data requests
• the user interface has been improved following stakeholder feedback
• following stakeholder feedback, data requests submitted in this module are processed hourly to speed up retrieval of the data
• grid definitions for the administrative regions of England are available for ‘multiple locations’ requests, and users can post-process the results (for example, by forming averages or identifying extremes)

Geography

MIDAS covers all of the UK. Data can be prepared by single point site (that is, longitude and latitude coordinates), multiple point sites, or rectangular grid area. Indicators can be processed over time at point sites, or at a given time over a grid area.

Time

MIDAS includes observational records, that is, past measurements rather than forecasts. The time period which Met Office data covers varies by indicator: for example, daily rainfall was recorded from 1853, daily temperatures from 1921, thunder from 1974, and pollen counts from 2010. MODI allows data to be extracted from 1971 onwards.

Indicators

Indicators are available in the following categories:

• temperature
• precipitation
• air pressure
• humidity
• solar irradiation
• visibility
• wind speed or direction
• pollen counts

Example extract

See case study 2 for an example of how this data can be used and combined with other data sources.

4. Food contamination module

Case description

Surveillance within EPHSS is concerned with environmental and chemical contamination of food, excluding radiation. The case (event) definition for surveillance for this module is an event, or incident that involves:

• chemical or environmental contamination of food or drinks for human consumption
• that poses a risk to human health (all age groups)
• in England or that affecting, or with the potential to affect, the English population, from the year 2000 onwards
• acute and chronic events would be in scope

Description

This module provides information and links to data on food contamination for use by UKHSA staff in managing risks to public health and for surveillance purposes.

Recent developments

This module went live in 2021. Recent developments include:

• information and links to the public data catalogues held by the Food Standards Agency (FSA), including those on chemical contaminant incidents and events that occurred in England and Wales
• access to the FSA’s private data catalogue of relevant one-off reports, datasets and resources
• information on the FSA dashboards including the Signal Prioritisation Dashboard, which acts as a food safety information system, the Risk Likelihood Dashboard, which flags potential and emerging food and safety risks, and new in 2024 added is the Register of Risk Analysis issues, which provides information on issues that are being considered through the FSA’s food and animal feed risk analysis process

The module provides access links to register for these dashboards.

EPHSS rollout and usage

Currently EPHSS is available to all UKHSA staff and phased access will be granted to external users from later in 2024.

New users need to apply for access by completing and submitting the online application form.

The system is accessed via the online portal.

More information about the system is available to UKHSA staff on the Pulse intranet.

EPHSS was launched to UKHSA staff in 2020 and the team have conducted a series of user engagement and training sessions including hosting a stand showcasing EPHSS at the UKHSA Annual Conference in 2023. A number of promotional materials and videos have been produced to advertise the functionality of the system. A user guide and scenarios for testing are also available, contact the team to arrange training events.

Current users in UKHSA include staff in RCE; Centre for Climate and Health Security (CCHS); Field Services; Data, Analytics and Surveillance (DAS) group; and HPTs.

EPHSS could also be used by others involved in providing services, data and intelligence and response to environmental issues affecting health.

When the system is available to external users, the Environment Agency, local authorities and emergency services will be encouraged to make use of the available data and can also add data sets for surveillance purposes. EPHSS outputs and resources are also available on the UKHSA Knowledge Hub Community of Practice (CoP). These can be accessed by signing up to the CoP via the KHub website and joining the group Environmental Public Health Tracking (requires login).

EPHSS case studies

Data from more than one module in EPHSS can be extracted and combined, as demonstrated below. EPHSS data could also be used alongside data from other surveillance systems, for example infectious disease data from UKHSA’s second generation surveillance system (SGSS) or Real Time Syndromic Surveillance.

Case study 1. Indoor air quality events surveillance

Monitoring of indoor air pollutants (APs) is a critical part of air pollution surveillance as people spend significant part of their lives indoors. Emissions can come from buildings, materials, and indoor equipment, or from human activities inside, such as the burning of fuels for cooking and heating. Using EPHSS, we can generate data sets to evaluate indoor air quality events.

Using data from CIRIS extracted from EPHSS between 2015 to 2023, we identified the number of events involving indoor APs. Using EPHSS, we can detect chemicals of interest that are recognised by the World Health Organization (WHO) and UKHSA as indoor APs of concern, as well as characterise the patterns and trends in which these events arise from. A customised environmental events surveillance module report was requested through EPHSS to obtain data on events with indoor air as the incident type between 1 January 2015 to 31 December 2023.

There were 9,334 total events or incidents reported in EPHSS between 1 January 2015 and 31 December 2023. Of these, 965 (10%) events involved indoor air pollutants. On average, there were 107 events per year. Incidents have slowly increased over time, with a sharp peak in 2023 (Figure 10).

Figure 10. Indoor air pollutant incidents recorded per year January 2015 to December 2023 in England

Of the 965 events, 277 (3% of all events, 29% of indoor air events) events involved chemicals listed in WHO and UKHSA guidelines for indoor APs. Among chemicals with WHO and UKHSA guidelines, carbon monoxide (CO) events comprised the most (89%) of all events.

The data set is summarised in Table 6 below. This shows the number and percentage of events reported per AP for those with WHO and UKHSA guidelines. A more comprehensive report on environmental events related to indoor air quality is in progress.

Table 6. Number of events involving indoor air pollutants with WHO and UKHSA guidelines between 1 January 2015 to 31 December 2023

Indoor air pollutant	Number of events reported	Percentage
Carbon monoxide	246	89
Formaldehyde	15	5.4
Styrene	6	2.2
Toluene	3	1.1
Naphthalene	2	0.7
Xylene	2	0.7
Benzene	1	0.4
Tetrachloroethylene	1	0.4
Trichloroethylene	1	0.4
Total	277	100

Despite 15 different chemicals on the WHO and UKHSA lists of indoor AP of concern, CO made up nearly 90% of events occurring. CO, chlorine, and mercury were the most common APs involved in these events, with the majority of these occurring in dwelling- accommodation-type settings. Notably, chlorine and mercury were not in either WHO or UKHSA guidelines.

EPHSS data has been used to analyse the frequency and composition of IAQ events and incidents in England, for events reported to UKHSA for the first time. One of the key advantages of EPHSS is its ability to extract and analyse data, enabling the development of hypotheses for further investigation and supporting data-driven recommendations.

Contribution by Rebecca Close, Adrian T. Lee and Emma Benham (Environmental Epidemiology Team, RCE)

Case study 2. EPHSS surveillance report: Rainfall and Cryptosporidium parvum, infections in South West England case study

Cryptosporidium is a genus of protozoan parasite with a seasonal pattern of infections in the UK, with spring peaks largely driven by Cryptosporidium parvum (C. parvum) infections. Meteorological variables, including temperature, humidity and rainfall have been observed to correlate with peaks of human cases and outbreaks of cryptosporidiosis. Transmission risks for C. parvum infections will likely change because of the changing weather patterns caused by climate change. The aim of this analysis was to describe rainfall patterns and association with the epidemiology of C. parvum infections in the South West of England, in order to support development of informed risk assessment processes, as well as investigate how Field Services teams in UKHSA can use routinely use available rainfall data in regional analyses.

Rainfall data was extracted from the MODI module. Total weekly rainfall for the South West was extracted for week 1 of 2016 to week 52 of 2019, using inverse-distance-weighted mean interpolations for a grid of 75 points covering the South West of England. Cases of non-travel- related C. parvum were extracted from the national cryptosporidium reference laboratory for the years 2016 to 2019, and described by age, sample collection date, and upper-tier local authority which was compared to the distribution of spatially mapped rainfall.

A directed acyclic graph (DAG) of the association between rainfall and C. parvum infections in humans was used to describe potential confounding and effect modifier variables and inform variable selection for a time series model of the association between rainfall and number of C. parvum infections.

Contributed by Kate Wilson (FETP Fellow based in Field Services South West team) on behalf of the research group: Nick Young, Neville Verlander, Alicia Barrasa Blanco, Rachel Chalmers and Bernd Eggen.

Future directions

Planned future work

Current work is focusing on making EPHSS available to external users. The team is working with service providers in the final stages to open up data sets and surveillance functions to external users. This will particularly be of interest to local authorities, the Environment Agency, Emergency Services, other resource planning agencies, public health agencies of the devolved administrations in the UK and academia. It is expected that phased external access to EPHSS will be ready in 2025.

The team is also scoping the options to include environmental exposure data from other sources, including from the Food Standards Agency, the Local Government Association, Environment Agency, Emergency Responders and local authorities.

Training sessions

The team will continue to roll out training and offer continued professional development (CPD) events across UKHSA and for new users. To discuss your requirements, please contact ephss@ukhsa.gov.uk

Evaluation of the EPHSS

An evaluation of the Environmental Events Surveillance (EES) module of EPHSS was conducted in autumn 2024. It found that the awareness of this surveillance was low in stakeholders. It made a number of recommendations for development. The EPHSS team are working on producing a plan to address these recommendations. The evaluation will be published here in time.

We interviewed stakeholders and users, conducted a user survey and reviewed documents to evaluate the EES on the following surveillance system attributes:

• simplicity
• flexibility
• data quality
• acceptability
• timeliness
• stability
• usefulness

Recommendations have been identified for each of these attributes of the surveillance system and will be taken forward to ensure that the EES continues to meet the needs of users.

Acknowledgements

The EPHSS team would like to thank many stakeholders for providing data for surveillance such as Health Protection Teams, the Environmental Hazards and Emergencies Department, trace element biochemical laboratories for reporting to LEICSS, the Food Standards Agency for providing the information in the food contamination module.

Acknowledgments are also due to the members of the UKHSA Environmental Events Surveillance working group, and LEICSS working group, and Environmental Epidemiology Team for their comments on draft versions and improving the report.

Main author

Dr Sarah Williams – UK-Field Epidemiology Training Programme Fellow, Environmental Epidemiology Group

Supervisors

Rebecca Close – Senior Epidemiological Scientist, Environmental Epidemiology Group, Radiation, Chemicals, Climate and Environment Directorate, UKHSA, Chilton

Maria Saavedra-Campos – Senior Epidemiological Scientist, UK-Field Epidemiology Training Programme

Contributors

Dr Helen Crabbe – Team Leader, Environmental Epidemiology Group, Radiation, Chemicals, Climate and Environment Directorate, UKHSA, Chilton

EPHSS team: Adrian Lee, Dr Bernd Eggen, Darren Bagheri, Dr Dina Fouad, Obiageli Onyekpe, Tej Patel

For queries relating to this document, please contact ephss@ukhsa.gov.uk