November 16, 2001

Officials from the United States Postal Service (USPS) have announced that sorting machines will now be cleaned with vacuums instead of forced air to help prevent the spread of anthrax. The wisdom of the switch has long been apparent to Donald Milton, lecturer on occupational and environmental health in the Department of Environmental Health, who had sent reports to the Postal Service for years suggesting such a change to forestall respiratory ailments suffered by some postal workers.

Milton has worked as an occupational medicine consultant at Fallon Clinic in Worcester, MA since 1986. He sees patients referred to him by primary care physicians and practitioners in the Occupational Health Department at the clinic, which contracts with USPS to provide care for work-related injuries and illnesses.

Over the years, Milton has evaluated several postal workers with recurrent sinusitis and asthma attacks that appeared to be triggered by their workplace. A definitive link is hard to prove, said Milton, but a lot of paper dust is generated in sorting facilities, possibly exacerbating respiratory conditions. The large sorting machines process volumes of mail each day, and tiny particles of paper dust dirty the machines. To clean them, postal workers historically used hand-held hoses to shoot compressed air through the machines.

"The problem is that when they blow out the dust, they blow it all over the place," said Milton.

He said that it remains unclear whether the forced air or merely the use of the sorting machinery creates particles fine enough to get into the lungs. "The machines themselves create a certain amount of aerosol because you have all this paper moving through there very quickly," he said.

The implication is that even if vacuuming cuts down on the dust in the air, the mere use of the machines may continue to produce a fine aerosol capable of invading the lungs of workers.

Addressing both concerns, Milton had recommended to USPS representatives who handle worker’s compensation claims that forced-air cleaning be replaced by vacuuming. He had also suggested that local exhaust ventilation systems be mounted onto sorting machines to help filter particles generated by the equipment. In response, employees who had become ill were generally moved away from the high-speed sorting machines, said Milton.

Since the anthrax cases have mounted, USPS has scrambled to find ways to eradicate the bacteria and protect workers. In addition to the use of vacuum, the service is considering irradiation to kill anthrax, troubling Milton.

"I’m concerned that they’re introducing another problem into the workplace rather than removing a different one," said Milton. "I’m sure it can be designed to be used safely, but people will be afraid of it, and there will be issues about accidents."