Proper Preparation Room Ventilation: Embalming and Formaldehyde Safety 101

When thinking about safety, every funeral home owner and embalmer must ask themselves: Is my preparation room air safe? To ensure your prep room is safe, you must first test for formaldehyde levels to see how you stack up to OSHA’s Permissible Exposure Limits (PELs).

The NFDA states: “Preparation room ventilation is the single most important factor in reducing health risks associated with formaldehyde exposure. Make sure that the ventilation system in your funeral home's preparation room is properly designed and operating effectively. An effective ventilation system assures that as much formaldehyde as possible is drawn away from the embalmer's breathing zone.” 

Once establishing a baseline for safe preparation room air, an owner and embalmer, should establish productive “engineering controls” or an effective air system as deemed by OSHA; this system must:

  1. Deliver safe air. It must protect the embalmer from exposure to toxic vapors. 
  2. Maintain a level of temperature, humidity and air circulation comfort.
  3. Be separate from the air system that supplies the public areas of the funeral home.

For the preparation room, at minimum the ventilating system must meet Occupational Safety and Health Administration (OSHA) standard 1910-1048 of no more than 0.75 parts formaldehyde per 1 million parts of air as an eight-hour time-weighted average.

Prep Room Ventilation Guidelines

The National Mechanical Code of the Building Officials and Code Administrators (BOCA) and the Heating, Ventilation, and Air-Conditioning Handbook of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) specify ventilation criteria for preparation rooms. These criteria for preparation rooms can serve as useful guidelines for effectively ventilating funeral home preparation rooms. 

BOCA requires a minimum of 12 air changes per hour for preparation rooms. The BOCA Code also requires that the air shall be exhausted to the outdoors, at an approved location on the exterior of the building. 

ASHRAE recommends a minimum of 12 air changes per hour be supplied to preparation rooms, and that at least two of the air changes per hour be outdoor air. ASHRAE also specifies that the room be negatively pressurized in relation to adjacent areas. 

An accepted industry practice of 15 air changes per hour for preparation rooms is a good rule of thumb and recommended by the NFDA.

Useful Tip: A source of makeup air should also be provided in preparationaration rooms to prevent excessive negative pressurization and to improve air mixing within the room. 

How To Calculate Air Changes Per Hour in a Preparation Room

Sample calculation for air changes per hour (ACH) 

Preparation room is 30 ft. long x 20 ft. wide x 10 ft. high with an 18-inch-diameter circular exhaust fan vent having an average face velocity of 860 FPM. 

  • ROOM VOLUME = 30 ft x 20 ft x 10 ft = 6,000 ft3 
  • VENT AREA = 3.141 x (9 in)2 = 254.4 in2 x 0.00694 = 1.77 ft2 
  • CFM = 860 FPM x 1.77 ft2 = 1,522 CFM (ft3 /min) 
  • CFH = 1,522 CFM x 60 min/hr = 91,320 CFH (ft3 /hr) 
  • ACH = 91,320 CFH I 6,000 ft3 = 15.2 ACH

VENTILATION SYSTEM CAPACITY - To determine the ventilation system capacity in cubic feet per minute necessary to obtain a desired number of air changes per hour. 

Sample calculation for ventilation system capacity 

Preparation room is 26 ft. long x 18 ft. wide x 9 ft. high and it is necessary to determine the number of cubic feet per minute that must be exhausted to obtain 15 air changes per hour. 

  • 4,212 ft2 x 15 ACH = 63,180 CFH (ft3 /hr) 
  • 63,180 CFH I 60 min/hr = 1,053 CFM (ft3 /min)

How To Improve Air Quality In Your Preparation Room

  1. Hire an industrial hygienist would measure the cubic feet per minute (CFM) of air exchange; you may need to be at a specific level of cubic feet per minute to increase air exchange and test under the Permissible Exposure Limit (PEL) to formaldehyde. 

  2. A mechanical engineer and/or HVAC engineer would measure airflow. You may need to increase your motor speed or adjust your ventilation to increase airflow. Angled piping ventilation can drastically lower your ventilation (sometimes as much as 30%). HVAC companies that deal with medical facilities will be best equipped to deal with this issue.

  3. Make this assessment internally before hiring an industrial hygienist or mechanical engineer. Develop a baseline understanding of CFM and ACH prior to reassessing ventilation entirely. We can help you with this exercise and save you money in the process. Contact us: