Graduation Year


Document Type




Degree Granting Department

Public Health

Major Professor

Raymond D. Harbison, Ph.D.

Committee Member

Thomas Bernard, Ph.D.

Committee Member

Yehia Hammad, Sc.D.

Committee Member

Joette Giovinco, M.D.


Condensation Nuclei, Nanometer, Particle Distribution, Lifetime Average Daily Dose, Optical Particle Counter


Ultrafine particles (UFPs) are present in the ambient atmosphere and are generated from atmospheric gases, pollution sources, and combustion. Candles emit carbonaceous soot particles similar to UFPs present in the ambient atmosphere. With the exception of lead, airborne concentrations of candle emissions have not been shown capable of causing cancer or cardiopulmonary disease during normal use. The purpose of this research is to determine the occupational risk associated with candle emissions.

Candle studies employ chambers to measure candle emission exposures and assess public health risk. Chambers used in previous studies did not match normal room conditions. They were affected by turbulence and high temperature, which affected particle distribution and constituent concentrations, while making it difficult to extrapolate the results.

The chamber designed for this study sought to avoid the problems noted above. This study also employed a room constructed to closely simulate a normal work environment. Candle suppliers and users were surveyed to determine occupational candle use and settings. Scented, unscented, and church candles were measured in both ventilated and unventilated environments. A condensation nuclei counter was used to measure UFPs from candle emissions.

Relative to previous chamber designs, results indicated a reduction in candle soot generation, no significant airborne concentrations of metals, and airborne concentrations of polycyclic aromatic hydrocarbons (PAHs), below occupational limits. Scented candles generated more soot than unscented candles.

UFP studies have demonstrated only weak associations between ambient UFP exposures and cardiopulmonary disease. However, ambient UFP exposures were used as a benchmark for candle soot exposures. The lifetime average daily dose (LADD) was calculated from the candle soot measurement data and ambient UFP data. Candle soot generated inside the test room ranged from 5.73 x 109 to 1.86 x 1011 number of candle soot particles inhaled daily compared to the 3.25 x1011 to 2.45 x 1012 soot particles inhaled in the ambient environment. The calculated candle soot dose was nearly an order of magnitude less than the calculated ambient dose. The conclusion is that candle emissions do not pose a health risk under normal occupational use.