OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

April 3, 1995

Mr. Exley E. Wical
1050 Forest Drive
Tavares, Florida 32778

Dear Mr. Wical:

This letter is in response to your questioning the use of ozone gas from ozone generators in a large room where 225 to 250 senior citizens play bingo. While ozone is occasionally suggested as a room air additive to freshen the air, we would not recommend the practice unless strictly controlled.

Ozone at concentrations above 0.05 parts per million (ppm) is associated with respiratory and other health related problems. Exposures to ozone above this level can result in headaches, throat and nasal dryness, bronchitis, decreased pulmonary function capacity, and other respiratory ailments. With a population of senior citizens, many of which may already have decreased pulmonary function, adding ozone may compound their problem. If ozone were to be added to the room, the levels would have to be kept well below 0.05 ppm to assure an adequate safety margin.

Most indoor air problems are associated with an inadequate supply of fresh outside air. The fact that you are bringing in 25% fresh air through the air conditioning system should be sufficient.

You indicated that people smoke in the room, this will of course compound any indoor air problems. The electrostatic filters will help, but realistically, smoking should not be allowed. By further increasing the percent of fresh air intake one will improve the air quality. As a quick check on the quality of the air one can look at the level of carbon dioxide. As the population inside a building increases the level of carbon dioxide will also increase. Ambient carbon dioxide levels generally run between 250 and 400 ppm. If the carbon dioxide level inside a building is above 700 ppm it is generally considered indicative of poor indoor air quality. This check should be done towards the end of the period when the room has been fully occupied. Increasing the fresh air intake is the usual recommendation if a carbon dioxide problem is found.

I hope that this information answers your question. If you have any further questions please contact Richard Fairfax of my staff at (202) 219-8036.

Sincerely yours,

Ruth McCully, Director
Office of Health Compliance Assistance Exley E. Wical
1050 Forest Drive
Tavares, Florida 32778

March 21, 1995

(I am Building Chairman for)
(the Lake County Shrine Club)
(Tavares, Florida)

Ms. Ruth McCully
OSHA Room N 3467
200 Constitution Avenue N.W.
Washington D.C. 20010

Dear Ms. McCully;

This letter is in confirmation of my telephone conversation today with Mr. Richard Fairfax.

I explained to him my concern about adding ozone gas, by use of ozone generators, to the air in a large room where 225 to 250 Senior Citizens play bingo; their average age is over 65 yrs. (We do not now add ozone gas to the air in this room.)

Please write a letter to me explaining why it is not advisable to add ozone gas to the air in our room.

We now add 25% fresh air through air conditioning system which gives us a complete fresh air change 4 times per hour, we also have 7 electrostatic air filters which filter the air 10.4 times per hour.

Any suggestions you may have to improve the quality of air in the above situation will be appreciated. Smoke is a problem.


Exley E. Wical