NIOSH Device Could Revolutionize Mine Safety

NIOSH senior research scientist Jon Volkwein testing the PDM in a mine. Photo by NIOSH

Lungs as black and hard as coal are the worst case of a disabling and potentially fatal lung disease called Coal Workers’ Pneumoconiosis, commonly known as black lung. The disease is caused by the inhalation and deposition of coal dust in the lungs. In the early 1970s, black lung affected approximately 1 in 3 long-tenured underground coal miners. By 1999 the rate was reduced to about 1 in 24, but ten years later it increased to about 1 in every 14. A decision was made to explore new technologies, and experts at the NIOSH Office of Mine Safety and Health Research developed a coal dust exposure monitor that is set to revolutionize the mining industry.

Current dust monitoring regulations date from 42 years ago, when Congress passed the Federal Coal Mine Health and Safety Act of 1969. For the first time in US history, the 1969 Act set coal mine dust exposure limits and sampling standards for the mining industry. It established 2 milligrams per cubic meter of air as the amount of coal mine dust a miner could be exposed to during an eight-hour shift. As a result of this law, black lung disease rates declined significantly over the next 30 years but were never eliminated. In 2007 deaths related to black lung caused or contributed to 525 deaths in the US.

"Then in 2000 black lung disease rates started to increase. This caused concern because the workers who started their mining careers under the new standards should have been disease-free. Why were disease rates on the rise? The Secretary of Labor’s appointed commission had previously suggested that the development of better monitoring instruments was needed to improve the monitoring of coal mine dust exposures. Unlike most workplaces, the mining workplace constantly changes, and controls in place one day may need to be adjusted as geology and conditions change as the workplace moves," said Ed Thimons, acting chief of the Dust Control, Ventilation and Toxic Substances Branch.

The NIOSH Office of Mine Safety and Health Research in Pittsburgh, PA developed a new personal dust monitor. Recently, this dust sampler was commercialized as the Personal Dust Monitor 3600 (PDM) and is set to modernize how coal dust exposure in the mining industry is monitored. It has the ability to provide real-time, continuous coal dust monitoring exposure.

Experts from the Dust Control, Ventilation and Toxic Substances Branch started development of a device that could monitor respirable dust on a continuous, real-time basis. “Measuring dust is not an easy thing. We went through a lot of hoops. Dust is a very complex material to try to measure. It changes temporally and spatially all the time. The classification of what really gets into your lungs and what doesn’t is highly dependent on the dust you are trying to measure,” explained Jon Volkwein, a senior research scientist.

Several PDM prototypes were developed and tested over a decade. The final commercialized monitor recently received certification as an approved coal mine dust sampling device. In October 2010, the Department of Labor’s Mine Safety and Health Administration (MSHA) published in the federal registry a proposed rule that features the NIOSH PDM as a key component to monitor miners’ personal exposure to respirable dust.