New emission limits for off-road petrol and diesel plant

The draft sets two stages of emission limits. Stage 1 comes into effect from 11 August - the date by which the new Directive must be implemented. Tighter stage 2 limits come into effect progressively from 2004 to 2008 depending on engine size.

The DfT expects the regulations to reduce hydrocarbon emissions from non-road petrol engines by some 86% by 2020 - equivalent to an 8.7% cut in total UK road transport hydrocarbon emissions from 2000.

There could also be a secondary benefit for CO₂ emissions. The DfT predicts a saving of 169,000 tonnes per annum - 0.11% of total UK CO₂ emissions.

The most significant pollutants from diesel engines are NO_x and particulates. As for petrol engines, the draft sets two stages of emission limits, although this time the date for stage 2 is the end of 2006.

The DfT expects the proposal to reduce NO_x emissions by 5.63kt and particulates by 1.16kt annually - cuts of 27% and 58% respectively for this type of plant.

The DfT estimates the total cost of hydrocarbon savings achieved at £82 per tonne saved, which is "highly cost-effective" relative to similar emissions control measures.

Similarly, if all costs of improving the diesel engines are allocated to one pollutant, then NO_x improvements would cost £856/tonne and particulate improvements would cost £3,932/tonne - both "very favourable" in comparison to other measures.

Furthermore, many manufacturers market their products globally and already produce equipment which complies with roughly equivalent US standards, meaning that they would face minimal development costs.

Given the improvements in fuel consumption, the DfT predicts that the net cost to UK businesses and consumers will be negative in the long term.

In March, the Council of Ministers issued the final text of a Directive to amend the same 1997 Directive.² A first round of emissions cuts will take effect from 2005 to 2008, with a second round from 2010 for all machinery except waterway vessels.