The Massachusetts Smoke-Free Workplace Law passed in 2004 required all enclosed work places be smoke free. But while exposure to secondhand smoke decreased from 2003 to 2010 — from 8 percent to 5.4 percent — certain work groups still experience a high prevalence, according to new research presented today at the American Public Health Association’s 141st Annual Meeting in Boston.

Since 2004 workers in installation, repair and maintenance experienced the highest prevalence of exposure to environmental tobacco smoke at 34 percent, according to the study. Prevalence in the construction and extraction industry was 22.6 percent while the transportation and material-moving industry was 19.8 percent.

In addition, exposure to environmental tobacco smoke at work was more commonly prevalent among male, non-white and younger workers.

“We’re seeing a steady decline in prevalence in exposure, but it’s clear that there are still specific groups of workers that deserve our attention,” said lead researcher Kathleen Fitzsimmons, MPH. “Findings like these that combine information about occupation and environmental tobacco smoke provide helpful information for evaluating comprehensive statewide smoke-free workplace laws and for targeting interventions to reduce risks.”

The results carried special significance in Boston. According to Kay Lazar of the Boston Globe, “smoking among Massachusetts workers declined from 18.5 percent in 2004 to 12.7 percent in 2010.”

The study was presented at APHA’s Annual Meeting, themed this year, “Think Global Act Local,” and was presented as a part of a session in Monday’s program, “Surveillance of occupational illnesses and injuries.”