OSHA Additive Formula

OSHA provides an additive formula in 29 CFR 1910.1000 for computing exposure to a substance containing two or more hazardous ingredients. Employers must monitor and compute the equivalent exposure using the following formula  

To illustrate the formula prescribed in paragraph (d)(2)(I) of Subpart Z, consider the following exposures  

Substance A—actual exposure at 500 ppm with a PEL of 1000 ppm Substance B—actual exposure at 45 ppm with a PEL of 200 ppm Substance C—actual exposure at 40 ppm with a PEL of 200 ppm 

Substituting the values provided earlier into the formula achieves the following results  

Since E (m) is less than the unity (1), the exposure combination is within acceptable limits. If the value exceeds one (1), consider the exposure as above the acceptable limit. 

Substituting the above values into the formula gives the following results  

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Explain in your own words the purpose of the OSHA Additive Formula found at 29 CFR 1910.1000. 

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