ENGLISH
25 - 33
6.5 PRECAUTIONARY MEASURES TO PREVENT EXPOSURE TO N2O
Environmental concentration limits of N
2
O. Maximum environmental concentrations of N
2
O must be
measured in parts per million (ppm).
The value must not exceed the imposed limits.
Compliance with the standards and precautionary measures listed below can reduce N
2
O concentrations
to values well below the required limits.
•
the morning before use, check the rubber hoses, connections, any other tubing, the balloon and
their tightness and replace them if damaged or at the proposed replacement date;
•
have masks of varying sizes so that they fit as comfortably and securely as possible on the
patient's nose and face. Leaks through masks are the most important sources of N
2
O in the area where
the dentist and assistant work.
•
make sure that the exhaled gas suction system is set correctly. Active suction is the most
effective method of reducing environmental N
2
O concentration.
•
The patient should be asked to restrict speech and not to breathe through the mouth after the
mask has been applied to the nose.
•
in children, crying, patient movements, the procedures used including the application of a topical
anaesthetic and the performance of loco-regional anaesthesia and the application of a mouth opener,
when the patient talks, laughs, cries or is uncooperative may be additional factors for pollution.
•
if available, activate an environmental ventilation system; staff should not stand between the
patient and the ducting that directs ambient air to the ventilation system outlet. Doors and windows
should be open.
At the end of the procedure the patient should be asked to breathe 100% O
2
through the mask for at
least five minutes. This time interval is necessary to eliminate N
2
O residues.
In paediatric dentistry, reluctant patients who do not tolerate the nasal mask and patients with medical
conditions that contraindicate the use of N
2
O (obstructive airway disease, emotional disorders, drug
dependence) should be treated with other techniques.
