Cement and concrete can be hazardous to your health—if the proper precautions aren't taken. As all concrete workers should know, wet concrete contains alkaline compounds, such as lime, that are corrosive to human tissue and can cause first-, second-, or third-degree burns with prolonged skin contact.
Dry cement and hardened concrete are less likely to harm skin, but airborne dust from mixing, cutting, and grinding concrete contains crystalline silica and is hazardous. It can irritate the eyes, with effects ranging from redness to chemical burns and blindness, depending on the level of exposure. Over the short term, inhaling high levels of concrete dust can irritate the nose and throat, causing choking and difficulty breathing. Construction dust exposure also can cause chronic bronchitis and emphysema. Prolonged or repeated exposure can lead to silicosis—a severely disabling and often fatal lung disease. Some studies suggest a link between crystalline silica inhalation and lung cancer.
When properly chosen, fitted, and used, personal protective equipment can reduce exposure and mitigate the harmful effects of concrete dust. Following the OSHA Standards for Respiratory Protection (29 CFR 1910.134) and Eye and Face Protection (29 CFR 1926.102) is a first step to help ensure workers' safety. But for dust-intensive operations, such as cutting and grinding, current thinking (and, increasingly, workplace safety codes) trend toward mandating the use of engineering controls on power tools to collect and dispose of dust.
A 2001 study by the National Institute for Occupational Safety and Health (NIOSH) found that workers grinding concrete surfaces were exposed to 35 to 55 times the recommended exposure limit for airborne dust containing crystalline silica. The following year, NIOSH evaluated the use of local exhaust ventilation (LEV) shrouds on handheld concrete grinders to find out whether they reduce dust exposure. Four different commercially available shrouds were connected by a flexible hose to a portable vacuum cleaner and tested while smoothing concrete walls. All the grinder/shroud combinations reduced dust exposure by more than 90%.
Evolving legal responsibilities
LEV shrouds and vacuum systems clearly are effective protective measures, but they're not mandatory in all cases or jurisdictions. Beginning next April, EPA regulations will go into effect requiring power tools used for sanding, cutting, or grinding to be equipped with dust shrouds. The dust shroud must connect to a certified HEPA vacuum that captures particulates as small as 0.03 microns.
To be sure about your legal responsibility, it's important to determine whether exposures at your jobs go beyond the allowable limits for overall dust and specific dusts. OSHA's current standard for dust that contains less than 1% silica is 15 milligrams/cubic meter (see 29 CFR 1926.55), but the permissible exposure limit for dust with higher silica concentrations is much lower. OSHA has an e-tools site (www.osha.gov) for silica to help you assess your silica exposure.
The U.S. Labor Department enforces Federal OSHA standards in 28 states, while 22 states and jurisdictions operate under complete state plans that cover both public- and private-sector employees. State plans generally are at least as stringent as federal standards.