Silica Threat

Silica is a known, high-risk danger, and exposure to it is common in the construction industry. Over the last decade, the number of lawsuits alleging that employers knew of the danger yet failed to take reasonable, responsible corrective action has grown sharply.

Unless Laborers wish to someday join these litigants, they should develop the habit of using respiratory protection at work. Studies show that they are routinely exposed to dangerous levels of respirable silica.

As far back as the 1930s, federal authorities warned contractors and workers on the danger of silica. Its very fine particles lodge in the lungs and cause the build-up of scar tissue. Eventually, through years of development, the accumulated scar tissue inhibits breathing and blocks the pulmonary function. Known as silicosis, this condition can be fatal.

Currently, OSHA has an occupational exposure limit (OEL) above which workers are required to use respiratory protection. However, on construction sites, where tasks and conditions change from day to day, effective testing is seldom employed. As a result, most construction workers are not required to wear respiratory protection and don’t. Thus, they are routinely exposed to dangerous silica levels, particularly when operating or working around mechanized hand tools.

A 2002 study in the Annals of Occupational Hygiene of four trades at 36 U.S. construction sites found that “silica exposures are grossly unacceptable.” The probability of overexposure for laborers ranged from 64.5 to 100 percent. It was similarly high, as well, for the other trades – painters, bricklayers and operating engineers.

The study also found that the mean (half above and half below) exposure for each trade was much greater than the OEL. The authors concluded, “It is clear that trade level interventions (engineering and administrative controls) will be needed to reduce silica exposure in this industry. Furthermore, additional interventions will be needed at the level of the individual worker to control for differences associated with particular sites, activities and equipment in a given construction trade.”

When operating mechanized hand tools, Laborers are at particular risk, even when wearing disposable or half-mask respirators. At such close range and high concentrations, an effective respirator must have a protection factor greater or equal to ten.

A more recent, 2004 study in the American Journal of Public Health, points out the deteriorated condition of the national highway system and highlights the likely impact of expanded highway repair work in the years to come.

The authors point out that, since the mid-1980s, the favored method of highway repair “utilizes large crews to cut, break up and remove large sections of concrete road before patching begins. These operations, sometimes completed during overnight work shifts, result in the generation of large amounts of dust.” For the study, air samples were collected and analyzed for a variety of typical repair tasks. In the vast majority, the samples consistently exceeded the OEL.

The authors noted that 39 percent of American construction workers are currently employed in highway and street work, and another six percent work on bridge, tunnel or elevated highway projects. With increased government allocations for rehabilitation of the national highway system, these percentages are likely to increase – and with them, the incidence of silicosis.

According to recent studies (see sidebar), overexposure to respirable silica on construction sites in North America is common and will become increasingly widespread as departments of transportation embark on extensive programs to repair the highways systems built over the decades since World War II.

New Jersey has emerged at the forefront of efforts to limit the silica exposure danger. With the help of the New Jersey Laborers’ Health and Safety Fund (NJLHSF), a number of innovative approaches are making headway.

New Law Bans Dry Sawing

In December, Acting Governor Richard Codey signed a law that bans the dry cutting and dry grinding of masonry materials on construction worksites. The law requires the use of wet methods to dampen dust and prevent exposures to silica. It appears to be the first such law in the nation.

In the event that wet controls are not feasible, the law requires the use of engineering or administrative controls to prevent silica exposures. These include vacuum ventilation, the designation of cutting areas isolated from other workers and the provision of a complete respiratory program for any workers who perform dry operations.

The law embodies a new approach that is increasingly encouraged by occupational health specialists: rather than requiring testing to trigger implementation of safeguards, the new approach designates construction tasks that typically involve over-exposure and requires protection unless proven unnecessary. Silica exposure is one example; noise exposure is another.

“In New Jersey, we’ve launched a war on silica,” says Ken Hoffner, Assistant Director of the NJLHSF, “and this law is an important step forward. It gets everyone’s attention on the danger of silica.” Already, Hoffner notes, because of the law, the School Construction Corporation, responsible for a huge building program throughout the state, has banned dry cutting and grinding on all its projects.

However, the law has no enforcement provisions and, if challenged, could be pre-empted by the Occupational Safety and Health Administration (OSHA) which has a far less restrictive standard in place.

Jackhammer Retrofits Available, Affordable

On another front in its war on silica, the NJLHSF took initiative to solve contractors’ problems in shifting to wet controls for jackhammer operations.

Last year, after the New Jersey Silica Partnership, in which the NJLHSF is an active member, developed and tested an effective wet control retrofit for jackhammers, “the issue became how to get contractors to use it,” says Hoffner. “We wanted to lower the $500 cost and make it easy for them to retrofit their machines.”

The original design required a weld which, in turn, made on-site retrofitting difficult and less likely. Hoffner developed a way around the weld and went online to find cheaper sources for the few, but necessary parts. “We’ve brought the total cost down to $200, and all the parts are easy to acquire,” he says. “We even go out to our signatories’ sites and retrofit the hammers for them. It only takes about 20 minutes.”

Now, with a contract for work at the Trenton train station where minimizing dust is important due to the high volume of commuter traffic nearby, one signatory employer has agreed to use retrofitted jackhammers throughout the project. Hoffner is hopeful that the example will gain the state’s attention and lead it to get involved in testing and promoting the engineering solution.

Other New Initiatives

Another prong of the war on silica is focused on the milling of road surfaces. “We’ve established a subcommittee to look into this,” say Hoffner. “We know it’s a significant source of respiratory silica, but we know the Europeans have developed a milling machine that controls dust. We want to tackle any obstacles to its widespread adoption in the U.S.”

Responding to the rising silica risk entailed in expanded highway repair work (see sidebar), the New Jersey Department of Transportation (NJDOT), a member of the New Jersey Silica Partnership, has begun including silica safety and health language in highway repair contracts. A similar approach to lead exposure risk has worked well in reducing lead levels in the blood of bridge painters.