Pollution inventory shows standstill on dioxin and PAH emissions

Little improvement in releases of dioxins and PAHs from industrial processes has been achieved in recent years, according to the Environment Agency's pollution inventory. Also revealed are reductions in emissions from coal-fired power stations despite increases in output.

The pollution inventory, launched in 1999, was a major step forward for public access to environmental information. It now covers industrial processes regulated under integrated pollution control, sewage treatment works and nuclear facilities.

Emissions data for 2001 have been available on the Agency's website for some time. The facility to use the site to compare companies' performance was inadvertently removed until recently.

The data need to be treated with some caution. Releases from a site can sometimes appear to change radically because of changes in measurement techniques. The data also contain a number of errors such as incorrect units and missing decimal points.

For some substances, such as PAHs and HFCs, the inventory says that no data are available, even though the information exists for individual sites. ENDS obtained sectoral data on these pollutants directly from the Agency.

Companies are required to report annual releases of 157 substances. New additions to the list include the phthalates BBP and DEHP, the suspected endocrine-disrupting compound bisphenol A, and nitrogen and phosphorus discharges from sewage works (ENDS Report 324, p 38 ). The first data on these pollutants, for 2002, will be published later this year.

Emissions of dioxins, especially from incinerators, have long been a focus of concern. In fact, the steel industry is now by far the biggest source. Corus' Port Talbot works is the largest source, releasing 9.5g per year, followed by the company's Scunthorpe and Teesside works.

Although steel works were identified as a major dioxin source in the mid-1990s (ENDS Report 240, pp 3-4 ), the sector's emissions have remained fairly static. Only Corus' Llanwern works has seen significant reductions, from 13.6g in 1998 to 2.6g in 2001, probably owing to reduced production at the site before its closure last year.

In January, Environment Minister Michael Meacher said that "dioxin emissions from the iron, steel and non-ferrous metal sectors have got to come down substantially."

Castle Cement's Padeswood kiln is the largest dioxin source outside the steel industry, releasing 2.2g in 2001 compared with 1.6g in 2000. The worst-performing incinerator is the Vetspeed pet crematorium with 0.8g - well above the worst municipal waste incinerator.

Steel works and cement kilns are also the main industrial sources of polycyclic aromatic hydrocarbons (PAHs). New evidence suggests that the scale of PAH releases may have been underestimated (see pp 9-10 ).

The inventory shows little sign of any recent reduction in PAH emissions. Castle Cement's Padeswood works is again a prominent contributor. The kiln is due to be replaced in 2004.

The inventory throws light on the chemical industry's releases of nonyl and octylphenols and their ethoxylates. These are known endocrine disruptors, and most uses are likely to be phased out in the near future (ENDS Report 333, p 39 ).

Sites with releases of NP/NPEs achieved major reductions in 2000. Uniqema's Wilton site cut NP discharges by 51% to 0.66 tonnes. However, discharges increased to 0.8 tonnes in 2001, making the site the largest single source. It was followed by Air Products' Clayton works at 0.22 tonnes.

Grimsby chemical firm Synthomer is the largest NPE source. It released 3.1 tonnes in 2001 compared with 4.7 tonnes in 2000. Synthomer's Batley site also discharged 1.7 tonnes of NPEs to sewer, while Uniqema released 2.3 tonnes of NPEs.

The inventory also reveals reduced discharges of cadmium from Britannia Zinc's smelter at Avonmouth although it remains the biggest source. According to explanatory data on the Agency's web site, Britannia has rebuilt its effluent treatment plant following "serious problems" with its performance. Cadmium releases to water were reduced from 852kg in 2000 to 454kg in 2001.

The largest source of nickel is Inco's Swansea works, which emits 4.7 tonnes of the metal to air each year. Although emissions fell from 5.3 tonnes in 2000, the inventory suggests a surprising increase from the 1998 figure of 51kg.

The inventory allows easy analysis of trends from a single pollutant from a single company. However, it does not readily enable trends in emissions across one or more sectors to be tracked.

One example of the information made available is the trend in emissions from coal-fired power stations in England and Wales. This shows how the increase in gas prices from 1999 led to increased output from coal-fired stations, and higher CO2 and NOx emissions. However, emissions of SO2 have continued to fall, reflecting greater use of flue gas desulphurisation equipment and a shift to low-sulphur coal.

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