Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more


  • Comment
Peak levels of low-level ozone show a decrease, but average levels of ozone are increasing, a new report published ...
Peak levels of low-level ozone show a decrease, but average levels of ozone are increasing, a new report published today reveals.

The report shows that whilst peak levels of low-level ozone have decreased by 20% in the last 10 years, average levels are still increasing.

Announcing the publication of the fourth report of the Photochemical Oxidants Review Group entitled 'Ozone in the United Kingdom' (1997), environment minister Michael Meacher said:

'I welcome this report. It contains some good news in that there is now evidence that peak ozone levels are decreasing in the UK. However, it also shows that there is no room for complacency. Ozone is an international pollutant - action in one country alone will not solve the problem - and that is why the government is playing an active part in formulating an European Strategy to control ozone levels further.

'In the EU we expect to gain approval on several directives aimed at improving air quality - on vehicle fuel quality and on emissions from passenger cars, from light commercial vehicles and from industrial sources. These will build upon improvements already occurring thanks to earlier legislation, in Europe and at home, to clean up road vehicles and industry. We are also planning new policies to reduce emissions from vans and HGVs.'

The main findings of the new report are that:

- ozone levels during the summer frequently exceed thresholds for damaging effects on crops, natural vegetation and human health throughout the UK. The largest exposure to these high levels occur in the uplands and in the south. However, peak ozone levels in summer smog episodes have decreased appreciably (20%) during the last 10 years, partly due to reductions in emissions but also to changes in the weather;

- average ozone levels are increasing. The significance of this for health is not known, but average ozone levels are responsible for damaging materials such as rubbers and plastics;

- ozone levels in London have been shown to be associated with changes in daily mortality and hospital admissions. There is a wide range of uncertainty in estimates of hospital admissions related to ozone with a range of 0.35% to 6.1% of admissions for respiratory disorders;

- the provisional objective in the National Air Quality Strategy (50ppb, expressed as a running 8-hour mean) is exceeded throughout

the UK at present and substantial reductions in emissions will be needed to achieve it.

Professor David Fowler, chairman of the review group, said:

'The focus of the report is on ozone in the UK but as the problem of photochemical oxidants is international, the data for the UK are considered in the context of the European ozone problem. The report also briefly considers photochemical oxidants other than ozone, including nitrogen dioxide, hydrogen peroxide, peroxyacetylnitrate and nitrous acid.'


The Photochemical Oxidants Review Group (PORG) is an expert group established by the Department of the environment, transport and the

regions. Membership of the expert group is drawn from the scientific and academic community in the UK and it is chaired by Professor David

Fowler of the Institute of Terrestrial Ecology, near Edinburgh.

The research carried out by PORG provides a valuable contribution to increasing the level of knowledge on the physical and chemical aspects of photochemical oxidants and associated precursors and their effects.

The PORG report is the fourth in a series produced by the review group. Earlier reports covered 'Ozone on the United Kingdom' (1987), 'Oxides of Nitrogen' (1990) and 'Ozone in the United Kingdom' (1993).

Ozone is a natural component of the atmosphere in the stratosphere (the 'ozone layer') where it intercepts UV rays. This report in concerned with tropospheric or low-level ozone which is produced by emissions from vehicles and industry, but also by natural emissions.

A network of ozone monitoring stations was established throughout the UK following the first Review Group report. The measurements from these stations have provided the necessary data to define the spatial distribution of ozone concentrations in the rural areas of the UK.

This report provides an analysis of UK measurements of ozone and other photochemical oxidants in ground levels air primarily for the period 1990 to 1995. In particular the report analyses the spatial patterns of ozone concentration throughout the UK and trends with time to identify the areas, crops and communities subjected to the largest exposure and to show the direction of any trends. The problem of tropospheric ozone is regional, and in some aspects global, and a brief consideration of the relative ozone climates in different parts of Europe is presented to provide the necessary perspective for the assessment.

Low-level ozone is formed by the reaction between two main precursors, volatile organic compounds (VOCs) and NOx, in the presence of sunlight. Ozone at ground level is an aggressive pollutant which can affect human health, interfere with plant growth and damage building materials. The long-range transboundary transportation of ozone and its precursors has ensured action on the problem at an international level.

The 4th PORG report is available from the Department of Environment Transport and the Regions, Room B550, Romney House, 43 Marsham

Street, London, SW1P 3PY (tel: 0171-276 8311) and from the Edinburgh Research Station, Institute of Terrestrial Ecology, Bush Estate,

Penicuik, Midlothian, EH26 0QB (tel: 0131-445 4343).

Air Quality Information can be found on:

CEEFAX (pages 410 - 417)

TELETEXT (page 106)

Freephone (0800 556677)

  • Comment

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions.

Links may be included in your comments but HTML is not permitted.