POLLUTION IN BATH Lecture Series

16 - 20 March 1998

THE ENVIRONMENT AND SUSTAINABLE DEVELOPMENT: PUTTING POLLUTION IN ITS PLACE
A Lecture by Professor Geoffrey Hammond, Bath University, on 16 March 1998

Prof. Hammond has a background of Mechanical Engineering in manufacturing processes and a particular interest in the environment. He is a Trustee of Bath Environment Centre.

There is no certainty in our knowledge about ‘Global Warming’. It is, however, recognised that technical innovations have first order effects, and that they almost certainly have secondary side effects. When evaluating the value and benefit of energy use relative to its effect on the environment, it is important to look at the whole life cycle of the production, and use of that energy. There is a wide acceptance now of the need for industrial or commercial development to be sustainable, so that the environment needs to be protected and adequate provision is made for the future, while the quality of life is retained, and that there is evident fairness for the community at large.
Improvement in the consumption of energy is, in significant measure, due to a decrease in the use of energy by industry as a consequence of a widespread decline in heavy industry. There is, however, a significant rise in energy use for transport.
Predictions of the possible dimension of Global Warming are based on modelling, which is subject to large uncertainty factors. Traffic growth undoubtedly causes congestion and pollution, but an increase in particulate dust, one of the pollutants, is expected to lead to cooling rather than warming. There is also evidence that Global Warming appears to correlate with the sunspot cycle. Nevertheless there is a wide consensus that urban transport exacerbates the levels of pollution, and is a problem which needs to be resolved.
Transport and land use need to be integrated. We have come to expect ample choice, accessibility and safety, while preserving mobility. More public transport is universally advocated and it is encouraging to note the greening of local government.
Roger Cloet

AIR POLLUTION AND BUILDINGS
A Lecture by David McLaughlin, Conservation Architect, B&NES, and Professor G. Allen, Bristol University, on 17 March 1998

David McLauglin has been concerned with conservation in Bath since joining the City Council 23 years ago. Prof. Allen is in the Interface Analysis Centre at the University, which uses a variety of instruments to determine the properties of materials.

In 1975, when he joined the Council, David McLaughlin carried out a listed buildings survey which mapped the state of cleanliness of the buildings in parts of Bath, especially The Circus. Only a few building were clean, the majority were still black with smoke deposits. Some buildings had been cleaned in 1956 (nos. 12 ,15 , 21 & 22 The Circus, which were owned by the Council) under an agreement, the Bath Terraces Scheme, between central and local government and the owners. By 1975 all except one of The Circus buildings had been cleaned.
By 1989 a Buildings at Risk Survey showed many more buildings had been cleaned but those in The Circus were getting dirty again. The circular form of The Circus was a contributing factor to smoke deposit in the days of coal fires in these houses (there are around 500 chimneys on the 33 houses) as the cup shape swirls the smoke onto the facades as the wind blows over the top. The corrosive effect is emphasised by the elaborate carvings. A cubic cm. of stone has an exposed surface area of 1sq. cm as part of a flat surface but carved into the shape of a nose on a statue its surface area may be several sq. cms.
After the Clean Air Act of 1956 reduced the amount of domestic smoke, the pollution and discolouration were caused by fumes from road traffic. This was explained byr of them alone (Fig.1) over 25 days, 5 parts per million (ppm) of sulphur dioxide causes a weight gain per sq. cm of surface of Bath stone of 3 milligrams (mg); 10 ppm of nitrogen dioxide causes 10 mg, but a mixture of both causes 35 mg.

The chemicals are carried on the surface of particles of soot, iron and fly ash which come from diesel engines and power stations. Many of these particles are very small, some only 1.5 microns (thousandths of a millimetre) (Fig.2, see next page) but they have a sponge-like structure and the large surface area absorbs the chemicals efficiently.
Inefficient engines without filters would produce larger particles as black smoke from the exhaust, less damaging to the lungs but visually offensive. After a time, the particles deposited on buildings become food for algae and lichens which turn the buildings green, but the corrosion of the stone goes on underneath.

 

WATER SERVICES IN THE NEXT MILLENNIUM
A Lecture by Dr Gareth Jones,Wessex Water, on 18 March 1998

Dr Jones graduated in chemistry before first practising as a public analyst and then entering the water service industry

Dr Jones gave a most informative talk which made clear that the importance and scope of this industry is rather taken for granted and its complexity and size not widely appreciated. We are in a period of change in water supply; more recycling of dirty water is becoming necessary to maintain supplies of potable water, and it is also necessary to recover from the state of delapidation into which the water industry had been allowed to fall by 1989. In future it must think in the long term and Wessex Water, a £1½bn p.a. business, is now studying possible sources of water up to 2075.
He described the two parts of the business, i.e. water supply (20% of the whole), and sewerage and recycling, making the point that it has no control over the raw materials of either, thanks to the Clerk of the Weather and to the way in which just about anything is flushed into sewers.
Consumption of water per head of population has increased by a third in the last 25 years and in hot weather it peaks at 50% above the average. 20% of the supply now leaks away, mainly from old pipes; about 40 leaks a day are repaired and Wessex Water's target is a leakage of not more than 9%. New reservoirs are being built, to be replenished not only from their catchment but also by pumping up from rivers when in spate. A water grid is being enlarged to enable water supplies to be switched within the region. Water pressure has recently been controlled by automatic valves; in Bath, owing to its hills, there are 80 pressure zones. Pressure is reduced at night when there is little demand but is increased if demand rises, if for instance there is a fire. The tap water supply is repeatedlyand automatically tested for purity and its purity is such that bottled water is quite likely to contain more bacteria. Underground aquifers will be increasingly important in future. Dr Jones referred to the Wareham scheme, the first of its kind in Europe, exploiting a pocket of chalk below clay where a large amount of water of potable quality can be stored.
Plastics are a real trouble in sewage. Chemicals now making their way into sewers (from such things as castoff medicines and hair shampoos as well as from chemical spillages) and today's stringent standards, are making it necessary to convert the present sewage treatment plants quite expensively into chemical as well as biological purification plants. More compact and less smelly membrane plants are replacing the percolation plants. Sludge is no longer dumped but is now being ‘biodried’ into sterilized granules making a most effective slow-release and safe fertilizer, more compact and easier than sludge to transport for future use.
Water treatment needs a lot of energy, but Wessex Water aims by 2050 to obtain all the power it requires by `green' methods, largely from sewerage.
In answering questions, Dr Jones said that in the longer term future the climate can be expected to be more violent, so greater holding and storage capacities will be needed. There will be a need to educate people to use water economically, and the increasing use of water meters is having that effect. Billing for water, by means of digital meters, will become more sophisticated and varied to circumstances.
Steps are in hand to educate children about water use and sewerage.
Work is in progress on prion degradation to ensure the safety of effluent from abattoirs; a sterilization temperature of 125°C is likely to be sufficient.
Wessex Water is investigating running undertakings in eastern Europe and elsewhere; it is also taking part in the work of the water charity and has ‘adopted’ Ethiopia where it has been able to improve water supplies.
John Coates

 

URBAN AIR QUALITY
A Lecture by Dr Andy Tubb, University of the West of England, on 19 March 1998

Dr Tubb is Senior Lecturer in Environmental Chemistry. He took his degree and Ph.D. at Bristol and then worked for S.W. Gas before going to Saudi Arabia to carry out environmental monitoring.

The urban environment is critical to the health of a large proportion of the population, who are, in many cases, exposed to it for their lifetime. Previously, industrial and domestic smoke was the problem; John Evelyn complained about the London smog in 1661, but since the Clean Air Act of 1956, traffic fumes are the main concern and these are increasing. The number of passenger-kilometres travelled by road increased from 200 bn in 1952 to 650 bn. by 1988 and goes on upwards.
Health can be defined by risk (what causes 50% of patients to die), perception (feeling well), or relative state (better today, thanks).
The 1990 Environment Protection Act was aimed at industrial sources and set up two registers, kept by the Environment Protection Agency for large sources, and local authorities for smaller ones. Very small sources, e.g. garages, are ignored.
The 1995 Environment Act required local authorities to manage air quality and in 1997 the National Air Quality Strategy specified eight pollutants and set limits for them, to be acheived by 2005. They were: benzene, 1-3 butadiene, carbon monoxide, lead, nitrogen oxides, ozone, sulphur dioxide and particulates (PM10, less than 10 microns in diameter). Phase 1 of the programme is for each local authority to review and assess the levels and the possibility of reaching the targets.
Phase 2 estimates the maximum concentrations of each pollutant in the background and at the roadside. Avon is a pilot area for this phase.
Phase 3 applies if it is considered the targets cannot be met and declares Air Quality Areas for special attention. Bath is likely to be one because of its geography and traffic congestion.
Dr Tubb then reviewed the measurements made in Bath in 1996. Sulphur dioxide is not too bad (30-40 parts per billion) but is not falling, as it has done nationally over the last ten years. It was suggested that Bath received it from the Avonmouth smelter or South Wales. It is mainly of concern for its effect on Bath stone, not health.
The real problem pollutants in Bath are nitrogen oxides, 45% of which come from transport, with peaks in winter rush hours, but lower levels in summer as sunshine destroys them (but increases ozone). Asthma is affected by particulates, which are fairly constant over the year.
The methods available for improving the air quality in Bath are well-known and being applied: pedestrianisation, restricting parking, improved public transport, road pricing, limiting vehicle access by permits. Closing roads is effective, much of the traffic disappears, it is not just displaced.
Don Lovell

 

ANNOYED BY NOISE?
A Lecture by Steve Peliza on 20 March 1998

The speaker is a graduate of Bath and Bristol Universities and an acoustic consultant.

After defining sound as fluctuations in air pressure he stressed the sophistication of our ears, since we can discriminate over a wide range of frequencies, between 20 and 20,000 hertz, although we tend to lose higher-frequency discrimination with age. Whatever the frequency, sound pressure levels from 10 to 140 decibels (the pain threshold) can be experienced by us.
Noise sources range from transport, industry, temporary and permanent constructions to entertainment, sometimes all together. Planning and building
regulations provide standards for buildings, roads, transport, industry, etc.and nuisances are subject to both statute and common law.
Various aspects of noise reduction and control were then covered in detail. Environmental Health Officers can issue abatement notices (preceding fines). Factories may face fines of £20,000 for each breach. Individual legal action is usually costly and provocative. Noise may be controlled by reductions at source ("turn it down!"), by moving away from a source (doubling the distance loses 6 db), by building barriers (reducing 5 - 10 dbs) or by improving insulation .Insulation materials vary in effectiveness - a masonry wall (reducing 45 db) is best, whereas a secondary double-glazed window with an air-gap will provide 35 - 40 db reduction if it is airtight (which may require built-in ‘attenuators’to provide ventilation!). Plasterboards with gaps are useful, although necessary ties reduce effectiveness. A review of factors involving floors, ceilings, ventilation and air-conditioning equipment, various aspects of noise barriers, etc.concluded the lecture.
In discussion some advice on BRLSI windows was given - essentially to provide thicker glass and airtight seals
.While acoustic tiles absorb noise, they are ineffective at low frequencies and insulation is generally preferable.
Pop music bass notes may cause tinnitus, but are generally much less harmful than industrial high frequency noise at high levels over long periods. Noise annoyance, however, is very subjective, varying widely with individuals.
Geoff Catchpole