Officials from Massport visited the Town Council Tuesday night to give an update on air quality monitoring in Winthrop.
 It appears that the new centerfield taxiway, which became fully operational in 2010, has had a positive impact on Logan Airport and Winthrop. Noise has been reduced because of the new runway. Officials said there is reduced noise because airplanes are not becoming congested at one end with the engines facing toward Winthrop. For pilots the new taxiway also helps with safety, congestion and efficiency. The airport now has a runway for every wind direction.
 A two-year study, with data before the construction of the centerfield taxiway and after showed that construction and operation of the centerfield taxiway has not deteriorated the air quality. Some of the parameters for the air quality have improved, the report stated. Monitoring sites for the study were placed at Annavoy Street, Court Road, Cottage Park Yacht Club, Coughlin Park, Bayswater Street and Constitution Beach. Councilman Russ Sanford questioned some of the data and commented that it looked like an average of the monitoring sites was taken and “not an honest result of the tests.â€
 Brenda Enos, assistant director of Capital Programs for Massport, said the study showed that 95 percent of chemical pollutant concentrations are below the benchmark values set by the Department of Environmental Protection. Also, 89 percent of the particulate concentration are below benchmark values. The report also showed that black carbon, which is influenced by the airport, has dropped as the number of airplanes using Logan has also dropped.
 Since 2000, the passenger levels are up from 27.7 million to 31.6 million, yet the total number of flights has dropped from 488,000 to 363,000. During the same period, due to reduced activity and improved engine technology overall noise and emissions are also down, said Flavio Leo, deputy director of aviation for Massport.
 “The trends are going in the right direction,†Leo said.