document: What 's the link ? A poor ventilation system that does little more than recycle old , stale air from one end of the building to another. ; Millions of American office workers are getting more than they bargained for when they inhale in a building that has no fresh air . Along with oxygen , they may be getting flu and other infectious bugs from their co-workers. ; That 's because , in today 's modern office buildings , recirculated air can mean recycled flu and other airborne infections . The evidence comes from various studies of tuberculosis , measles and flu that spread in a manner that can only be explained by poor air ventilation. ; `` Modern office buildings are tight , '' says Jon Rosenberg , public health officer in California 's occupational health program . `` In order to conserve energy , they 're often sealed . '' ; Experts say the problem is not the same as `` sick building syndrome '' -- a situation in which workers are exposed chronically to toxic chemicals and gases emitted from carpets , furniture and other building materials . Nor is it to blame for last month 's outbreak in Richmond of Legionnaire 's disease -- an illness caused by a bug linked to wet , damp spaces rather than poor ventilation. ; But as in `` sick building syndrome , '' it 's the airtight environment that sets the stage for problems . Lack of windows is not necessarily the culprit . `` If it has a good ventilation system ... you do n't necessarily have to have a sick building , '' Rosenberg says. ; But , alas , many modern ventilation systems recirculate indoor air with little or no fresh air . So the infectious bugs that a worker exhales at one end of the building can end up , via the ventilation system , being inhaled at the other end. ; `` The building is not the source . People are the source , '' says Dr. Edward Nardell , who studies airborne infections for the Massachusetts Department of Public Health . `` Very bad ventilation makes the system worse . '' ; In a study published in the August issue of the American Review of Respiratory Diseases , Nardell and colleagues at Harvard Medical School found that an outbreak of tuberculosis documented in one unidentified government building could have been cut in half had the ventilation been better. ; The study found that 40 percent of the building 's workers -- or 27 of 47 -- were infected with tuberculosis from one 30-year-old sick employee . The infection rate was as high in some distant parts of the building as it was next to the sick employee. ; `` By recirculating the air , you spread it throughout the building , '' says Nardell . `` People who had no direct contact with this case , might have been exposed in far reaches of the building . '' ; If tuberculosis can spread in poorly ventilated buildings , so can other infectious bugs . Respiratory infection experts say that flu viruses and measles are easier to spread than TB. ; `` This particular study deals only with TB , '' says Dr. Jonathan Samet , a respiratory-disease expert at the University of New Mexico , `` but the observations may apply to other organisms , such as the respiratory viruses that cause flu . '' ; Building workers had complained for years about poor air quality. ; The building 's ventilation system permitted circulation of some outdoor air -- 15 cubic feet per minute -- a low level commonly found in buildings since the 1930s . Even lower levels of outdoor air ventilation , below 10 cfm , have become common since 1973 , the post-oil embargo era. ; In the study , Nardell estimated that if outdoor air ventilation in the government building had been doubled -- to about 35 cubic feet per minute , a level that Massachusetts recommends for buildings where smoking is permitted -- only half as many workers would have been infected with tuberculosis. ; Other studies have documented : ; -LRB- check -RRB- Flu spreads quickly on airplanes where ventilation systems consist entirely of recirculated air. ; -LRB- check -RRB- Measles are transmitted by infectious air in a pediatrician 's waiting room. ; -LRB- check -RRB- Tuberculosis can spread in homeless shelters , prisons and hospitals where ventilation is poor. ; Flu spreads much more easily than TB . `` It may survive several hours in dry air , '' says Vernon Knight , a respiratory virus disease expert at Baylor College of Medicine in Houston . `` In those tight buildings , they continue to recirculate it , and they probably build up . '' ; Nardell and others recognize that the solution to this problem -- fixing or replacing ventilation systems to include more fresh air -- can be expensive . Flu and colds will probably never be eliminated from the workplace entirely , and it may not make sense to install a new ventilation system unless the air quality is very low. ; In his tuberculosis study , he found that the biggest benefit comes from improving the worst ventilation systems that allow very little fresh air . If the ventilation is moderately effective but not ideal , further improvements yield only a slight decrease in infectious illness. ; `` There 's only so much you can do , '' Nardell says . `` There 's going to be a price of living together in a communal society . '' ; YOU 'RE INTERESTEDEmployees who think that poor air quality at their workplace is contributing to health problems can call Cal-OSHA , a state agency that monitors worker safety and health . In San Jose , Cal-OSHA can be reached at -LRB-408-RRB- 452-7288 .
extractive_keyphrases: tuberculosis study infectious air ventilation system poor air ventilation airborne infections