Nearly half of all full-time employees of state and local government units belong to labor unions and similar employee labor orginizations, according to a Census Bureau report.

The report, based on surveys made in October 1977, says there are 9.9 million full-time state and local government employees (plus nearly 3 million part-time) and 4.7 million of the full-timers belong to unions. This is 47.8 percent.

The figures reveal a much higher degree of unionization among public employees than in private industry, where, according to Labor Department estimates, only about 24 percent are unionized. The highest full-time unionionization ratio is among local school districts, with 60 percent. The lowest is among county empolyees, 35 percent.

The occupation with the highest (by far) unionization rate is fireman, with 73 percent. Police unionization is about 53 percent, with welfare and hospital workers near 38 percent.

The state with the highest percentage of unionized full-time state and local government employees is Hawaii, with 83.8 percent. The Distric of Columbia, with 60.1 percent of its full-time employees unionized, and Maryland, with 57.7 percent, are well over the national average. Virginia, with 26.9 percnet, is well below.