Photos of the London Olympic Park, Stadium and Orbit Tower.
(CNN) -- Less than a week from the opening ceremonies, allergists are warning that some Olympic athletes may suffer breathing problems due to air pollution in London.
The amount of nitrogen dioxide in London is comparable to the level of nitrogen dioxide in Beijing before Beijing banned half of the cars in preparation for the Games, and London has done little to control traffic, says Dr. William Silvers, an allergy specialist and a member of the American Academy of Allergy, Asthma & Immunology (AAAAI).
Demanding workouts in the polluted air could spell trouble particularly for those athletes that already have conditions such as asthma or exercise-induced bronchoconstriction (EIB), a narrowing of the airways that makes it hard to move air out of the lungs, according to AAAAI.
Silvers believes that the pollution levels are an underplayed aspect of the Olympics, and more needs to be done in order to address the potential health problems for athletes.
Elite athletes have an increased incidence of EIB, says Dr. Silvers. The AAAAI estimates 1 in 5 top athletes and 1 in 6 of all Olympic athletes have to deal with EIB.
People with EIB experience coughing, wheezing, chest tightness, and shortness of breath during or after exercise but are otherwise healthy. Pollution can worsen these symptoms can could adversely affect the athletes' performance.
Silvers suggests it could mean the difference between first and second place for Olympic athletes with breathing problems. Marathon runners could be particularly affected by this, according to Silvers.
"Up to half of Olympic athletes with EIB were previously undiagnosed," says Silvers. He suggests it's therefore important that athletes are evaluated before their competitions begin.