Keeping all Welsh air good!

Air quality monitors track pollution hot-spots

Situated in the south west of Wales, in a largely rural area bordering the Brecon Beacons, Carmarthenshire’s air quality is predominantly good. However, there are areas of concern where major roads pass through some of the County’s larger towns, including Llanelli, Carmarthen and Llandeilo, where air quality is dominated by the effects of road traffic. The County Council is therefore testing new monitoring technologies so that it will be better able to track the effects of improvement measures.

The sensor!

The sensor!

Carmarthenshire County Council operates a network of passive diffusion tubes as part of its commitment to Local Air Quality Management under Part IV of the Environment Act 1995. However, in 2013, Air Monitors supplied the Council with a new type of air quality monitor, ‘AQMesh’, that is able to provide continuous air quality readings for a range of important parameters. This new technology is small, wireless, lightweight and battery powered, which means that it can be quickly and simply mounted in almost any location.

The Council’s monitoring programme has identified Nitrogen Dioxide (NO2) from traffic emissions, mostly diesel vehicles, as the pollutant of greatest concern. A number of locations in the centre of Llandeilo have been shown to be in breach of European air quality standards, so an Air Quality Management Area (AQMA) has been established in the town. Whilst NO2 levels are not sufficiently high to cause immediate health effects, the current levels could cause adverse health effects over the long term, particularly in people suffering from respiratory conditions such as asthma and chronic obstructive pulmonary disease.

NO2 reduction by about 25µg/m3 is the main objective of the air quality action plan, but the Council is determined to ensure that all pollutants remain at safe levels, so the ability of the AQMesh to monitor a wide range of parameters (Ozone, Carbon Monoxide, Sulphur Dioxide, Nitrogen Monoxide, Nitrogen Dioxide, Temperature, Humidity and Atmospheric Pressure) is a major benefit.

Four features
Stephen Hoskin from Air Monitors says: “There are a number of important new features in AQMesh that are fundamentally changing the way that air quality is monitored; firstly, it can be located where air quality matters most – where people are breathing.

“Secondly, in comparison with large reference stations, with only a small drop in levels of accuracy, the cost of monitoring is reduced dramatically, which means that users will be able to measure air quality in more locations, and this will reduce the UK’s current dependence on modelling to ‘guesstimate’ air quality.

The unobtrusive sensor in situ!

The unobtrusive sensor in situ!

“Finally, by providing near real-time data over the internet, useful air quality data can be made available to a much wider audience via smartphones, tablets and computers.”

The AQMesh in Carmarthenshire is being operated by Oliver Matthews, one of the Council’s Environmental Health Practitioners with specific responsibility for air quality. He says: “In the past we have not continuously monitored this range of parameters because doing so would have involved the installation of a large, expensive air quality monitoring station that would have probably required planning permission.

“These reference stations offer high levels of accuracy, but come with large capital and operational costs, and cannot typically be moved, whereas the AQMesh can be quickly attached to a lamp post or other item of street furniture at a fraction of the cost.

“Alternatively, we could install passive diffusion tubes, one for each parameter of interest, but the disadvantage of this method is that the tubes are left in place for four to five weeks, so we are only provided with an average figure over that time, with no indication of the peaks and troughs that occur. For example, a recent road closure resulted in the diversion of traffic and, with the benefit of AQMesh, we were able to track a significant short-term rise in NO2.”

With the assistance of key stakeholders, the AQMA draft action plan has identified a number of options to improve air quality, and the AQMesh unit has been installed in order to help assess the success or failure of each initiative.

Interestingly, the development of the AQMA action plan benefitted from essential gas main works that were required in Llandeilo because this involved the closure of the main trunk road (Rhosmaen Street) for a period of up to three months, which provided an opportunity to identify the effects of traffic diversions on air quality.

Options that are being considered as part of the action plan include improving traffic management and seek to prevent vehicular ‘stop/start’ and promote a smooth flow of traffic. Typically, these options could include the provision of extra parking outside of the AQMA, the removal of some on-road parking within the AQMA, better parking enforcement, relocation of bus stops, reviewing pedestrian crossings and improvement of bottle necks.

Summarising Oliver says: “The network of diffusion tubes has enabled us to identify hotspots, and these are the locations at which the AQMesh will be of greatest use because we will be able to study trends and look for the causes of elevated pollution levels at specific times of the day.

“Data from the AQMesh are provided on a website via the ‘Cloud’ so, looking forward, this technology has the potential to make a major difference to air quality improvements and to the transparency and availability of data. For example, it may become possible to integrate air quality monitoring with automatic traffic management.”

Water replaces coal in bringing prosperity to Cardiff!

Water quality has been a central theme in a redevelopment project that began with the creation of the Cardiff Bay Development Corporation in April 1987. This article examines the role that water quality has played in the remarkable transformation that has taken place in Cardiff and explain how monitoring technology has developed to the stage whereby any person, anywhere in the world, can view live water quality data at multiple locations in the Cardiff Bay via the YSI EcoNet web-based system.

Cardiff owes much of its history to the Industrial Revolution of the 1790’s, which stimulated mining in the valleys of South Wales. By the 1880’s, Cardiff had transformed from one of the smallest towns in Wales to the largest and its port was handling more coal than any other port in the world.

On the eve of the First World War in 1913, coal exports reached their peak at over 13 million tonnes.  However, following the Second World War, demand for coal declined and international markets were lost as other countries developed their own steel industries. Trade was increasingly lost to container ports and by the 1960’s coal exports had virtually ceased.

Peter Gough from the British Environment Agency was a student in Cardiff University during the 1970’s and remembers the poor state of the local rivers: “The Taff was as black as coal and incapable of supporting most aquatic life.  At its worst, in the 19th century there were reports of livestock dying after drinking from the river.”

By the early 1980’s Cardiff Bay had become a neglected wasteland of derelict docks and mudflats. Much of Cardiff’s population suffered from social exclusion with above average levels of unemployment.

The regeneration of Cardiff Bay was undertaken to create a complementary mix of housing, open space, commerce, leisure and industrial development. The project also included the construction of a barrage across the mouth of the bay to create a 200-hectare freshwater lake, fed by the rivers Taff and Ely, which would link all of the proposed developments and provide both aesthetic and recreational benefits.

Environmental considerations were extremely important in the proposed redevelopment plan and water quality protection measures were defined in the Cardiff Bay Barrage Act 1993, which stipulated that water quality objectives shall have regard to:
(i) the recreational or other purposes for which use of the water is permitted by the Development Corporation, and
(ii) the needs of the fish in the water and of migratory fish passing to or from it.

Water quality was required to meet the relevant standard as specified by the National Rivers Authority (now the Environment Agency of England and Wales). This standard was the maintenance of a minimum dissolved oxygen (DO) level of 5mg/litre. Peter Gough explains: “When the construction of a barrage was first proposed, concerns were raised for the ecological recovery of the catchment. Cardiff Bay had a huge tidal exchange which resulted in significant pollutant dispersal and a barrage would clearly prevent that and represent a risk to water quality in the future impoundment.

“One of the main concerns was the potential effect of the barrage on migratory fish such as salmon and sea trout, which were starting the process of recolonisation in the 1980s.  They are very sensitive to pollution and to low DO levels in particular. A range of mitigation measures were therefore built into the proposed development plan.”

Construction of the barrage took place between 1994 and 2000 at a total cost of £220million, and in 2000 Cardiff Council took over from the Cardiff Bay Development Corporation and through the Cardiff Harbour Authority (CHA) established five main objectives:

      1. Maintaining the best environmental standards
      2. Improving access to and around the Bay
      3. Developing water use
      4. Increasing the quality and range of facilities
      5. Liaising with communities, commercial businesses and other organisations

Environmental issues
The main issues of concern for the CHA are debris management, flood defence, migratory fish, algae, birds, groundwater levels, problematic species and of course water quality.

Prior to the creation of the barrage, debris (typically 1000 tonnes/annum), which was mostly derived from the two rivers that fed the bay, would have been washed into the Severn Estuary. However, CHA now employs booms to collect debris for transfer to controlled areas.

Flood control has also improved with the barrage. In the past, heavy rain in combination with heavy rivers and a Spring tide would have resulted in flooding. However, CHA is now able to closely monitor and control water levels in the bay with the barrier’s sluice gates. For example, in 2001 a 1:57 year rainfall event resulted in a bay water level rise of just 20cm.

Migratory fish were referred to specifically in the requirements of the Act mentioned above, so the barrage was constructed to incorporate a fish pass to allow migratory salmon and sea trout to return to the rivers Taff and Ely to spawn. In addition, young salmon have been released into the rivers, firstly as part of an impact monitoring programme, and latterly as a mitigation measure. The bay now supports healthy populations of freshwater fish such as barbel, chub, dace, gudgeon, roach and rudd, and Peter Gough reports an improving salmon, trout and grayling population in the two main rivers and their tributaries. He says, “The fish pass incorporates a counter so we have been able to measure the success of the joint activities with the CHA. The focus on migratory fish has proved to be an elegant way to protect and report water quality because most people understand that if salmon can live in a river, the water quality must be good.”

A further stipulation of the Act related to potential effects on local properties from changing groundwater levels. Groundwater surveys were therefore undertaken before the construction of the barrage and have continued ever since.

Invasive species represent a threat to the ecology of the bay and zebra mussels are currently the most significant. Capable of rapidly colonising any structure within a water body, zebra mussels can become a significant problem as they adhere to the surfaces of boats, jetties, anchors, chains, pipes etc. As filter feeders, each zebra mussel typically filters up to 2 litres/day and David Hall from CHA believes that the biomass is so large that the entire volume of the bay could pass though a zebra mussel every two weeks. As a result of this filtration, the water is very clear and David says “This means that cormorants find it easier to prey on fish that swim near the surface, so the balance of fish species has moved in favour of bottom feeders.”

Water Quality
Salmon are unable to survive in low DO water and this was undoubtedly a factor in choosing DO as the main indicator of water quality. However a wide range of other water quality parameters are also monitored.

DO levels are affected by a number of different factors. For example, windy weather helps to aerate the water and cold water is able to ‘hold’ higher levels of DO than warm. As a result, warm windless summer days pose the greatest threat. However, pollution discharges such as combined sewer overflows can also reduce DO levels. Algae have the potential to lower DO levels following death and eutrophication, but David Hall believes that algae in Cardiff Bay, on balance, have a positive effect on DO as a result of photosynthesis.

CHA employs two methods with which to combat low DO levels. An aeration system extends across the floor of the bay and provides an opportunity to circulate and aerate the water. This system is fed by air compressors which feed over 600 diffusers through a network of 20km of pipes. However, in extremely low DO conditions, CHA is able to deploy an oxygen barge which feeds pure oxygen directly into the worst affected water.

YSI multiparameter water quality monitoring sondes have been deployed in Cardiff Bay since the beginning of barrage construction. Initially, these were strategically placed logging instruments from which data was collected manually at regular intervals, but as CHA’s Steve Ellery explains: “This was labour intensive and only provided a historical view of water quality, which meant that our ability to respond to poor water quality was limited and often delayed. We therefore installed 6 YSI buoys in 2000 and began to collect data via radio.”

The radio telemetry provided CHA staff with access to live data which transformed their ability to respond quickly to low DO. However, the radio systems had to contend with interference and line of sight issues, so in 2008, the buoys were connected to YSI’s EcoNet system, which automatically publishes live data to a dedicated website.

A map showing the location of the YSI buoys is shown on the home page of YSI Hydrodata  and provides any web user with access to live water quality data. This data is collected at 15 minute intervals from the buoys via GSM and stored on a secure server that hosts the web data.

Two of the buoys are fitted with water quality monitoring sondes at both 1m below the surface level and also at 1m above the floor of the bay. The remaining seven buoys have one sonde monitoring at 1m below the surface.

YSI sondes are compact, rugged battery powered instruments capable of logging data from a broad selection of sensors that have been designed specifically to withstand the most harsh aquatic environments. The sondes in Cardiff Bay are fitted with sensors for DO, pH, conductivity, salinity, temperature and turbidity, but many other sensor options are possible.

Commenting on the reliability of the sondes, Steve Ellery says: “We have been delighted with the performance of the YSI 6-series sondes because they have enabled us to demonstrate extremely high levels of compliance with the DO requirement. The initial sondes were replaced after about six/seven years and we now run eight spare sondes so that when recalibration is due we can simply swap sondes without incurring any downtime in data collection.

The ability of the monitoring network to deliver live data means that we are able to respond to low DO levels very quickly and accurately, and as a result, over the last five years our compliance performance with the 5 mg/l DO has been over 99.9% every year.”

Users of the YSI EcoNet system do not always opt for live web data display but Steve Ellery has never regretted the decision to do so. He says, “If the sondes were less reliable we would not wish to display inaccurate data, but since their performance has been so good, it has been great to be able to provide the data to anybody with an interest.”

In addition to the buoy based monitoring network, CHA also takes monthly water samples from six locations for the laboratory analysis of a wide variety of parameters including phosphate, nitrate, ammonia, BOD and bacteria.


Looking back over the changes that have taken place in water quality in recent decades, Peter Gough believes that the Taff may be the only capital city river in Europe with salmon spawning within the city and says, “This is testament to what has been achieved in a relatively short period of time.”

The YSI water quality monitoring network has enabled the CHA to provide live data to the public and to ensure the protection of water quality in the bay. This has ensured that the area has become an attractive environment for all forms of life including human beings.

David Hall has lived in Cardiff for the whole of his life and believes that the protection of water quality has been key to the success that the city has enjoyed in recent years. He says, “If you include the housing, pubs, restaurants, sports facilities etc., the development of the Cardiff Bay area represents a total investment of about £2 Billion.

“The overwhelming success of this area hinges on the aesthetic quality of the bay; the water is clean, wildlife is thriving and many thousands of people enjoy a wide variety of leisure activities. Prosperity has once more returned to Cardiff, and this time, it’s not coal we have to thank… it’s water.”

Real-time Monitoring – through swell and high water


Estuaries on the west coast of Wales represent some of the most challenging conditions for environmental monitoring. However, staff from monitoring solutions company YSI Hydrodata and the British Environment Agency specialists have combined to develop a solar powered water quality monitoring pontoon which is providing 24/7 data that previously would have been an impossible dream.

The pontoon was installed in March 2010 and the Environment Agency’s Ian Myers says “a number of technical innovations have been deployed on the pontoon which have helped to deliver an unprecedented volume of water quality data that has made a major contribution to our understanding of water quality conditions in the area.”

YSI water quality monitoring buoys are in operation all over the world. However, Environment Agency staff needed to monitor estuarine water quality continuously in a particularly challenging environment – the Burry Inlet near Llanelli in south west Wales. With a tidal range of over 8 metres in a narrow channel, a pontoon was chosen to reduce drag in high flows and to provide the monitoring equipment with greater protection.

Commenting on the challenging conditions, YSI’s Darren Hanson says “We would normally recommend a ‘YSI Pisces’ catamaran for applications such as this, but Environment Agency Evidence staff were able to combine existing resources with a great deal of ingenuity to save money on the platform. This meant that a greater proportion of the budget could be allocated to the variety of equipment and instrumentation supported on the platform”

Burry Inlet SPA

The Burry Inlet is located between the north coast of the Gower Peninsula and the south-east coast of Carmarthenshire. The large estuarine complex (6,628 hectares) is composed of extensive intertidal sand and mudflats, a large sand dune system, and the largest continuous area of saltmarsh in Wales (2,200 hectares). The estuary is fed by three main rivers; Loughor, Lliw and Llan.

Since Roman times, Burry Inlet has been an important cockle fishery, providing food and work for local people. However, mass cockle mortality in recent years has resulted in an investigation that has yet to identify the cause of the cockle deaths. In addition to helping the Environment Agency to undertake its statutory monitoring duties, the monitoring pontoon is also providing a wealth of data to support the ongoing investigation.

Stuart Thomas is Project Manager, Burry Inlet Investigations for the Environment Agency Wales. He says “There has been a strong underlying improvement in the Burry Inlet over the last 20 years; the water quality is good and the trend is for further improvement. The addition of the monitoring pontoon has helped us to record water quality at a far greater frequency, which is particularly beneficial in estuaries because of the changes that take place during the tidal cycle and extreme weather conditions.”

The Pontoon and Instrumentation
The pontoon was designed and developed by the EA’s Innovation Team in Evidence and  has an aluminium frame, is fitted with two solid foam floats and has a keel made from a heavyweight chain, which keeps it upright. The design has been adapted with a hydrofoil (a streamlined wing structure) to allow it to lift out of the water in high currents. It was successfully tested before deployment in the estuary by towing against the flow in the river Avon near the Environment Agency’s Bath office. The water quality monitoring sonde (YSI 6600V2-4) is protected by purpose built retractable tubing which enables the monitoring of shallow waters and protects the sonde if the pontoon rests on a sand bank.

A water-tight telemetry box was originally fitted with 2 x 10W solar panels. This is fixed to the top of the pontoon and contains the GPS-GSM buoy tracker, a 12 volt 38aH battery and power supply and YSI Econet ‘Data to the Web’ telemetry equipment.

The mooring consists of a medium sized fluke anchor and 1.5m of very heavy grade chain. This is attached to approximately 15m of lighter galvanised chain that rises to the surface which, in turn, is attached, via a cleat, to a large fishing float which is designed to take the weight of the mooring.

If the pontoon moves a certain radius away from its last known position, it will alarm by sending a text message to a pre-programmed phone number.

Water Quality Monitoring
Traditional water quality measurements by routine boat patrols are costly, time-consuming and represent a higher level of risk to staff. Occasional measurements also fail to reveal the majority of water quality events that might take place as a result of tidal cycles, storms or pollution incidents. In contrast, the YSI sonde is set to take measurements from a range of sensors every 15 minutes. This means that the sonde is able to store as many readings in just one day as a monthly boat would collect in eight years.

Sonde data are stored on an internal datalogger and also transmitted via YSI Econet telemetry to a dedicated website.

There are two sondes (YSI 6600 V2-4), duty and standby; both of which are fitted with sensors for the measurement of conductivity, salinity, temperature, pH, oxidation-reduction potential (ORP), dissolved oxygen (using the ROX™ optical DO sensor), turbidity, chlorophyll, and blue-green algae. The turbidity, Chlorophyll, DO, pH and ORP sensors are provided with wiped fouling protection.

These sondes have been designed for long-term deployment with minimal maintenance and calibration requirements – approximately four times per year. Commenting on her experience with the sondes Carol Terrill from the Agency’s National Laboratory Service based in Llanelli said: “The use of a sonde guard covered with copper tape did reduce barnacle growth, but a lot of barnacles still had to be removed at the end of each deployment. The decision to switch to a copper alloy sonde guard, part way through the deployment although in early autumn resulted in zero barnacle growth on the sonde guard. We also noticed that fitting a copper mesh screen to the conductivity probe prevented barnacles from getting inside the conductivity cell. The probes all seem quite robust and stood up well to the battering they received during storms.”

The benefits of continuous data
Collection of data obtained remotely from the pontoon is a far safer method of monitoring and allows water quality to be monitored during storm or pollution events that may otherwise be missed by routine boat patrols.

Ian Myers believes that monitoring system at Burry Inlet has made a radical contribution to the understanding of water quality conditions in the area. “We now have instantaneous access to almost live data in addition to an archive so that we can identify trends,” he says. “We can also check the status of the monitoring equipment itself, which helps to optimise servicing and data quality.
“The sonde wiper systems, copper guard and copper tape have all extended deployment times and the DO, salinity, conductivity, pH, temperature and algae readings are cross-checked with spot samples taken from the boat; which further improves confidence in the data.”

Looking forward
The data from the pontoon has corroborated the boat monitoring and also provided greater insight into the changing conditions within the estuary over tidal and diurnal cycles. As monitoring continues, the Agency and other interested parties will be able to plot water quality over a yearly cycle and to detect pollution incidents as they occur. As a result, stakeholders will be able to apply more detailed scientific data to water related issues in the Burry Inlet.