BOX 6.1
A Simple Qualitative Method to Verify Adequate Laboratory Chemical Hood Ventilation


200 g (approximately 250 mL) of dry ice pellets (5-to 10-mm diam)

Shallow bowl, approximately 3-L volume

1 L water at 43 °C (mix hot and cold water as needed to obtain the target temperature)



1.   Open the chemical fume hood sash to simulate actual operation. Position laboratory equipment as close as possible to where it will be used.

2.   Place the shallow bowl approximately 15 cm into the chemical fume hood and in the center of the sash opening.

3.   Add 1 L of the warm water to the bowl.

4.   Add the dry ice pellets to the water.

5.   After approximately 5 s, observe the vapor flowing from the bowl.

6.   Repeat the observation while a colleague walks past or moves around the chemical fume hood to simulate actual operation.

7.   If vapors are observed escaping the chemical fume hood face, the result is a fail; none escaping is a pass.

In the event of a failure or if there is any concern about proper operation, contact appropriate personnel and take corrective action. Adjustment of the sash opening and the baffles and relocation of equipment in the chemical fume hood should be considered.

NOTE: In addition, airflow should be measured on an annual basis.

     than regular safety glasses to protect against hazards such as projectiles, as well as when working with glassware under reduced or elevated pressures (e.g., sealed tube reactions), when handling potentially explosive compounds (particularly during distillations), and when using glassware in high-temperature operations.

   Chemical splash goggles or face shields should be worn when there is a risk of splashing hazardous materials or flying particles.

   Because chemical splash goggles offer little protection to the face and neck, full-face shields should be worn in addition to safety glasses or goggles when conducting particularly hazardous laboratory operations (e.g., working with glassware under vacuum or handling potentially explosive compounds). In addition, glassblowing and the use of laser or ultraviolet light sources require special glasses or goggles.

   Operations at risk of explosion or that present the possibility of projectiles must have engineering controls as a first line of protection. For instance, in addition to chemical splash goggles or full-face shields, these operations must be conducted behind blast shields, in rubber-coated or taped glassware.

Ordinary prescription glasses do not provide adequate protection against injury because they lack side shields and are not resistant to impact, but prescription safety glasses and chemical splash goggles are available.

Similarly, contact lenses offer no protection against eye injury and do not substitute for safety glasses and chemical splash goggles. They should not be worn where chemical vapors are present or a chemical splash or chemical dust is possible because contact lenses can be damaged under these conditions. If, however, an individual chooses to wear contact lenses in the laboratory, chemical splash goggles must be worn. Note that there has been a change in recommended guidance regarding the wearing of contact lenses since the previous edition. Many organizations, including the National Institute for Occupational Safety and Health (NIOSH) (HHS/CDC/NIOSH, 2005) and the American Chemical Society (Ramsey and Breazeale, 1998) have removed most restrictions on wearing contact lenses in the laboratory.

6.C.2.3 Avoiding Ingestion of Hazardous Chemicals

Eating, drinking, smoking, gum chewing, applying cosmetics, and taking medicine in laboratories where hazardous chemicals are used or stored should be strictly prohibited. Food, beverages, cups, and other drinking and eating utensils should not be stored in areas where hazardous chemicals are handled or stored. Glassware used for laboratory operations should never be used to prepare or consume food or beverages. Laboratory refrigerators, ice chests, cold rooms, and ovens should not be used for food storage or preparation. Laboratory water sources and deionized laboratory water should not be used as drinking water. Never wear gloves or laboratory coats outside the laboratory or into areas where food is stored and consumed, and always wash laboratory apparel separately from personal clothing.

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