The purpose of this study is investigate to the effect(s) of chronic occupational exposure to N20 and volatile anesthetics on the extent of oxidative stress (DNA damage and the generation of the biochemical markers) in operating room staff, with different levels of exposure to halogenated hydrocarbons, in comparison to unexposed controls (Intensive Care Staff), and to determine the relationship between the degree of oxidative stress and psychological stress, as assessed by validated psychometric measures.

This is a single blinded randomized, controlled and prospective clinical trial comparing oxidative stress status in two groups.

Subjects in two groups will be matched for gender, age, smoking habit and employment duration and will be randomized into one of the two groups of:

1. Pediatric OR Staff, and
2. control (e.g; ICU staff)

Biomarkers of oxidative stress will be measured in two different time points in each subject, (Monday Morning and, Friday afternoon of that same week->40 hours in Operating room or Intensive Care Unit).

The relationship between oxidative stress and psychological stress will also be assessed by validated psychometric measures.

Inclusion Criteria:

1. CHOR-Staff who work > 40 hours per week in the operating rooms (Anesthesiologists, CRNA, Surgeons, Nurses)
2. NOR- Intensive Care Unit Staff who work > 40 hours per week in Intensive care unit (Physicians, Nurses, APN'S)

Exclusion Criteria:

Staff with the following history will be excluded:

1. Therapeutic exposure to radiation
2. On chemotherapeutic agents
3. History of General Anesthesia during the past two years

Twenty operating room staff and twenty intensive care unit staff (40 Total Participants)