The weak dollar is affecting US researchers working abroad and threatens American involvement in flagship projects say physicists at the CERN laboratory. Grants paid in dollars to researchers in Europe are now worth substantially less than they were a year ago.

?It's hurting, and people are scrimping and making up for it in other ways,? says Mike Tuts, a programme manager for the US collaborators on Atlas, a component of the Large Hadron Collider (LHC) at CERN, which will look for the Higgs boson, dubbed the God particle.

In January 2006, a US dollar bought about ?0.83, in January 2007 that was ?0.77. Today it is worth only ?0.69. Although US researchers at CERN receive adjusted pay to reflect the cost of living, these corrections are not keeping up with the change in exchange rates. ?It's already starting to hurt and it's making people nervous,? says Joel Butler of the US section of the Compact Muon Solenoid experiment, another part of the LHC.

And it is not just the researchers who are suffering. Local costs incurred by US teams at CERN have risen significantly. Butler says that additional funding to deal with these expenses will be requested, but it is not guaranteed to be forthcoming. ?In the end, if we don't get some relief, we will probably have to reduce the size of the community and do more work remotely,? he says.

Similar problems may befall CERN itself, which straddles the border between France and Switzerland. Changes in exchange rates between the euro and the Swiss franc ? between 2002 and 2006 ? cost the LHC project 40 million Swiss francs (US$35 million), says Florian Sonnemann, head of resource planning and controlling at the facility. ?This SFr40 million had to come from the contingency we have for this project,? he says.

However, at the moment, it is the Americans who are really suffering. ?We used a rather poor exchange rate in the budget planning.? says Tuts. ?Ultimately it will impact on the science.?