I Can Feel Benzene Comin' In The Air Tonight, Oh Lord

Air quality is vital to a healthy environment, but it can be very hard to monitor and control. In many instances, airborne pollutants can be completely undetectable without appropriate equipment. In other instances it can be quite visible. Smog is a common occurrence in many large cities and can lead to various adverse health problems. Various levels of contaminants are permitted within the workplace and the standard set by OSHA determines how much is allowed. All of the various chemicals as well as the Occupational Exposure Limit are created by OSHA.

Thick Smog In Beijing - CNN.com

Air can be sampled and tested in various ways. Personal air sampling devices can monitor the air in ones breathing zone. The breathing zone is a radius of approximately 9-10 inches from the face. The OSHA standards for air quality vary from substance to substance. The Occupational Exposure Limit (OEL) for Benzene in the air is 1.0 ppm. The OEL is the standard set by OSHA. This is typically measured in parts per million, which is so fractionally small it is almost unfathomable.

A Personal Air Sampling Device

Air can be sampled via pump rotameters. In this case, a pump is connected to a tube and air is pulled into the tube. One calculates the flow rate by timing the solution rising up the pump. We calculated the flow rate and benzene levels for an 8 hour sample in class with the following results:

Q= The Flow Rate

500mL / 14.7 sec = Q

1000mL / 29.4 sec = Q

34.01 = Q

8 hour = 480 mins

480 min (2.041ppm) = 979.2 L*ml^3 / 1000 L

The final calculation was that the air contained 0.749 ppm Benzene, which is within the OSHA standards. 

The NIOSH method number for sampling Benzene is 1501. The method used is a sorbent tube containing coconut shell or charcoal. 10% of the sample should be blanks. The sample stability of benzene is less than four hours. This means that the sample must be sent to a lab within hours after being taken, which is a huge drawback for the person who is sampling.

An Image of Charcoal Sorbent Tubes

Sampling air and maintaining air quality creates safe and healthy environments for workers. The standards set by OSHA create a limit on the amount of a substance that can be in an environment before it becomes problematic to the employee. Many toxic substances aside from benzene can affect air quality. For example, in nail salons, workers are constantly breathing in harsh chemicals like acetone. The OSHA standard for acetone is 1000 ppm. Another potentially toxic substance is formaldehyde, which is very typical in lab settings as a preservative. The OSHA standard for formaldehyde is 0.75 ppm which, meaning that it is even more toxic than acetone. 

In a workplace, people are often put in situations where they may not be certain what they are inhaling. These standards and methods for controlling and monitoring are put in place to protect the health and well being of all workers.