Corporate Action to Reduce Air Pollution — Atlanta, Georgia, 1998-1999

Morbidity and Mortality Weekly Report, March 3, 2000

Ground-level ozone, a colorless gas, is a major constituent of smog. Since the early 1980s, controlled studies have demonstrated that exposure to elevated levels of ozone reduces inspiratory capacity in humans [1]. In addition, ecologic analyses have indicated that daily emergency department visits for asthma exacerbations are elevated following days of high ozone pollution [1-4]. The Partnership for a Smog-Free Georgia (PSG) is a state-sponsored program to reduce the number of days that ground-level ozone exceeds the national ambient air quality standard (NAAQS) in metropolitan Atlanta by providing federal and state subsidized commuting alternatives for local business employees. This report summarizes commuter data from three PSG partners to estimate reductions in emissions and monthly vehicle miles traveled that were associated with enrollment in PSG.

NAAQS for ground-level ozone is 0.12 parts per million during a 1-hour period. From May 1 through September 30, 1999, ambient ozone levels in Atlanta exceeded this standard on 24 days, maintaining the 13-county metropolitan-Atlanta region as an area of "serious" nonattainment of NAAQS. In December 1997, the Georgia governor's office issued an executive order requiring all state agencies to reduce single-occupancy vehicle commutes by at least 20% on days when NAAQS is expected to be exceeded. PSG was instituted during the summer of 1997 to help achieve this goal. Results of a study of three PSG partners were calculated using vehicle-miles-traveled formulas and emissions factors provided by the U.S. Environmental Protection Agency [5].

Georgia Department of Transportation. On May 1, 1998, the Georgia Department of Transportation introduced a comprehensive smog-reduction program to its 1900 employees (Table 1). Baseline rates of commuter behaviors were assessed in April 1998 by a departmentwide survey asking employees how they "usually" commuted to work during the preceding year. Commuting behaviors were then assessed as part of the daily log-in procedure at each employee's computer terminal. Before PSG program initiation on May 1,91.4% of Georgia Department of Transportation employees reported that their "usual" method of commuting was in a single-occupancy vehicle. During this baseline period, employees commuted an estimated 1033 vehicle miles per month, volatile organic compound emissions were an estimated 393 pounds per 100 employees per month, and nitrogen oxide emissions were an estimated 351 pounds per 100 employees per month [5]. During May-August 1999, the percentage of all daily commutes in a single-occupancy vehicle decreased to 73.6% (a relative decrease of 19%), and vehicle miles traveled and their associated emissions decreased 11%.

Georgia Board of Workers' Compensation. The Georgia Board of Workers' Compensation, which has 117 employees, became a PSG partner in May 1998 (Table 1). The agency conducted a baseline survey of their employees' "usual" commuting behaviors during March 1998. Beginning in May 1998, all employees completed a daily survey of commuting behavior. Most (62.1%) employees usually commuted using a single-occupancy vehicle before initiation of the PSG program. Before PSG implementation, Georgia Board of Workers' Compensation employees commuted an estimated 799 miles per employee per month, emitted 303 pounds of volatile organic compounds per 100 employees per month and 272 pounds of nitrogen oxides per 100 employees per month. During May--July 1999, the percentage of all commutes in a single-occupancy vehicle was 44.9% (a relative decrease of 28%). In addition, PSG program implementation was associated with a monthly decrease of 145 vehicle miles traveled per employee per month and an estimated 18% decrease in emissio ns.

Georgia Power/Southern Company. Georgia Power/Southern Company has been conducting a prospective monthly survey of employee commuter behaviors since April 1997. During the baseline period of March--April 1998, an average of 587 (20%) of 2885 employees participated in the alternative commuting program (Table 2). Following the repetition of seasonal promotional activities in April 1999, the average increased to 41.5% during May--July 1999 (a relative increase of 52%), and emissions were reduced 12%. To rule out any influence of seasonality on observed findings, participation rates for March--April 1999 were compared with those from March--April 1998. The employee participation rate increased 32%.

Reported by: J Pierce, MBA, Partnership for a Smog-Free Georgia. S Carter, MBA, Georgia Power Company, Atlanta. D Orlando, Air, Pesticides and Toxics Management Div, Environmental Protection Agency, Region 4 Office. P Hortman, MS, Georgia Dept of Transportation; T Risko, MBA, State Board of Workers' Compensation; KE Powell, MD, Div of Public Health, Georgia Dept of Human Resources. Air Pollution and Respiratory Health Br, Div of Environmental Hazards and Health Effects, National Center for Environmental Health; and an EIS Officer, CDC.