NITROX TRAINING

There has been a quiet revolution happening in recreational diving. You surely must have noticed it, everyone now appears to be sporting green and yellow stickers on their tanks, and talking about oxygen clean regulators, rich mixes and equivalent air depths. Nitrox has come of age in the UK with its promotion by the recreational diving training agencies. But what is it?

Nitrox refers to any breathing mixture of Oxygen and Nitrogen. As a human being you have breathed Nitrox since the day you were born (21% Oxygen, 79% Nitrogen). Enriched Air Nitrox - EANx - is simply where the fractions have been altered, so that the diver is breathing more oxygen. For example EANx 36, is 36% Oxygen, 64% Nitrogen. (The percentage of oxygen (O2) comes first). Easy, isn't it!
So why do we, as recreational divers, want to reduce the amount of nitrogen that we breathe? The length of time the diver can stay on the bottom and still directly ascend to the surface (no stop time), and the amount of decompression that must be done if the diver stays longer, is determined by the amount of nitrogen (inert gas) that has been absorbed by the body during the dive. By increasing the fraction of O2, and so reducing the amount of nitrogen, bottom time can also be increased and the safety stop/decompression obligation reduced.
Alternatively if EANx is dived on air tables (instead of EANx tables), then this gives the diver 'best protection'. It increases dive safety by significantly reducing nitrogen loading, compared to a dive conducted on straight air (21% oxygen). ANDI (American Nitrox Divers International) call EANx 'Safe Air'. Remember, no gas can be classed as truly safe, but by using EANx you are safe(r).

Some diving physiologists advocate that diving EANx also helps reduce subclinical, decompression sickness (i.e. does not present symptoms). General signs include: tiredness, weariness, apathy and a headache. Sounds familiar? This is where the body's tissues have been loaded by nitrogen and micro bubbles have been formed. These 'silent bubbles' are small enough not to cause decompression illness symptoms, however the transfer of oxygen to the tissues is not so efficient, hence we end up feeling tired. By diving an EANx mix, the body's tissues do not get so loaded with inert gas. Nitrox can also be used at a more advanced level, whereby a much higher fraction of Oxygen in a separate decompression cylinder is used to accelerate decompression stops. The diver will then switch from their diving gas to their decompression gas at a safe depth for the mix and then breath this gas to the surface.

Nitrox certainly sounds too good to be true doesn't it! So what's the catch? Normally a recreational diver only tracks one gas and it's effects on the body - nitrogen loading using diving tables. By increasing the amount of O2 breathed, it becomes necessary to track the oxygen. Too much O2 can be toxic. By getting proper training and employing correct dive techniques this problem can be avoided.

There is a wide choice of programmes from the various UK diving agencies. This is an overview of the introductory nitrox qualifications available for the recreational diver. All the major UK training agencies were asked for details of their EANx courses, the ones who responded are featured here. They are (in alphabetical order):

• BSAC (British Sub Aqua Club)
• IANTD UK (International Association of Nitrox and Technical Divers UK)
• PADI (Professional Association of Diving Instructors)
• SAA (Sub Aqua Association)
• SCOTSAC (Scottish Sub Aqua Club).

This is one qualification that, whatever training agency you are from, every diver should seriously considering doing simply from the safety point of view. By deciding your needs and ambitions you should be able to select the relevant programme for the type of diving that you wish to do.

All recreational divers can gain a nitrox qualification, without having to go down the route of 'going tech', with multiple tanks and extreme depths. Nitrox is not a deep diving gas, many divers use it today to enhance their day to day diving in the surface to 30 metres range. However diving with EANx involves more discipline and pre-dive planning to stay within the safe limits of the mix being used. The training will give you this.

To gain most from these courses, in the classroom divers should have a good working knowledge of basic diving physics and diving tables. Diving wise, being comfortable in the water and good buoyancy will give a good working base to enhance current skills and develop new techniques.

Certification is earned through personal performance and knowledge demonstrated throughout the course. With some agencies, each part of the course concludes with an assessment and only those who pass each assessment will be certified. Additionally, students with unsafe attitudes or demonstrating bad diving habits will not be certified. Advanced nitrox divers are also expected to adopt a self-reliance policy. This does not mean a solo diving policy.

One key point often not considered when purchasing training is the Instructor's background and experience in the subject that they teach. Look at their training pedigree and track record. Are they out there doing the dives? Do they practice what they preach? It may be worth switching agencies simply to guarantee a higher quality of education. Remember, cheap is not always the best.

The price of the course will vary and all costs quoted in this article are a rough guide - they will vary from centre to centre. It is worth checking to see what is covered in the price, for instance are the course materials included? (Student workbooks, manuals and tables). Will you need to pay extra for the gas used? Additionally you should check out if any other equipment is required, and will the trainer provide it or do you have to hire it? On the more advanced courses a separate decompression cylinder and regulator is essential. (Don't forget a delayed SMB and reel, they are standard equipment for almost all the courses with every training agency).
Expect to take a theory exam at the end of the course. The Training Agencies are not out there to trap you, just ensure that you have grasped the knowledge they have imparted to you.

BSAC advocated Nitrox for recreational diving in 1996 and to date they have certified over 1,380 Nitrox divers. They have simplified this subject, ensuring that all essential areas are covered and put across to students in an easy manner. The supporting materials for the courses also reflect this thinking - the glossy student notebooks are in readable English and nicely laid out.

Nitrox Diver - BSAC
A one day, classroom study course that introduces the use of EANx 32 and 36 within no-stop times. Subjects covered include:

• Nitrogen and Nitrox Diving
• Revision of Gas Laws
• Oxygen and Human Physiology
• Safe use of Nitrox with BSAC 88, EANx 32 and 36 tables
• Safe use of Nitrox with air and Nitrox computers
• Equipment for Nitrox diving
• Practical session on analysing gas

Advanced Nitrox Diver - BSAC
A two day course (Day one, classroom studies, Day two, two open water dives) that introduces dive planning and practical skills when diving and decompressing using EANx. Subjects covered include:

• Use of EANx 50, both as a diving and decompression gas
• Monitoring Oxygen uptake and effects of Oxygen
• Nitrox mixing and analysing (including a practical session on analysing gas)
• Dive organisation and management
• Decompression equipment and configuration

Combined Nitrox Diver - BSAC
A two day course (Day one, classroom studies, Day two, two open water dives) that introduces the Diver to the meticulous dive planning and practical skills required when diving and decompressing using enriched Nitrox mixtures. Subjects covered include:

• Advantages and disadvantages of Nitrox
• Use of EANx 50, both as a diving and decompression gas
• Pressure and Nitrox mixes, including calculating partial pressures of Oxygen
• Decompression planning
• Dive organisation and management
• Equipment for Nitrox diving, decompression equipment and configuration

The costs include the registration fee, certification card, badge and certificate, the appropriate study work book and a set of BSAC Nitrox tables (tables for Nitrox and Combined Nitrox courses only). The cost does not include equipment or gas.

IANTD has been a major player in Nitrox diving and training since the late 1980's, coming into the UK market in 1992. To date IANTD UK have trained over 8,000 divers (this figure coves all courses through to Trimix). The nitrox courses cover all essential areas in great depth, especially with regard to the calculations behind the tables to ensure that the student has a good grounding in EANx theory.

Nitrox Diver - IANTD
A two day course (Day one, classroom studies, Day two, two open water dives) that introduces dive planning and practical skills when diving and using EANx. The diver may elect to dive the mix on EANx tables or conservatively using their dive computer or air tables with an added diver safety margin. Subjects covered include:

• Nitrox Overview and History
• Use of Nitrox mixes up to 40%
• Pressure Laws
• Oxygen and Human Physiology
• Equivalent Air Depths
• Nitrox equipment and gas preparation techniques

Advanced Nitrox Diver - IANTD
A two day course (Day one, classroom studies, Day two, two open water dives). This program is designed to extend the diver's knowledge with O2 mixes of 22% to 40% and up to 50% for decompression. It further develops diving skills and provides a greater understanding of the Nitrox diving concept. Subjects covered include:

• Nitrox review
• Oxygen use/mis-use and toxicity
• Gas Laws
• Dive planning and Equivalent Air Depths
• Oxygen and Decompression Clocks/Tracking
• Equipment Configuration

IANTD UK has 47 Training Facilities and 5 Technology Centres around the country.

PADI launched their Enriched Air Diver Speciality course in 1996 in the UK. The course has been structured in such a manner as to simplify this subject. Two 'fun' (no skills/tasks being performed) dives are conducted with emphasis placed very much on pre and post dive procedures - analysing gas and calculating oxygen exposure after the dive.

Enriched Air Diver - PADI
A 12 hour (approx.) course that introduces the use of EANx, covering all mixes up to 40%, within a no decompression environment. It teaches the use of Nitrox as a substitute for air to increase dive safety, or to be used in conjunction with Nitrox tables and computers to increase bottom time. Subjects covered include:

• Basic Physics Revision
• PADI diving tables
• Oxygen tracking
• Equivalent Air Depth calculations
• Practical session on analysing gas
• Protocols when purchasing Nitrox

1993 saw the SAA endorse Nitrox diving in the UK - they were the first air training agency to teach an introductory Nitrox qualification to the recreational diver. All essential areas are covered during training, including blending and mixing systems. The Decompression Manual by Bob Cole is required reading for all SAA divers, whether they attend a Nitrox course or not.

Nitrox Diver - SAA
A 9 hour (approximately) classroom study course that introduces the use of EANx 28%, 32%, 36% and 40% advocating no decompression diving. Subjects covered include:

• Nitrogen and Nitrox Diving
• Oxygen and Human Physiology
• Equivalent Air Depth calculations
• Buhlmann diving tables
• Blending and mixing systems
• Equipment for Nitrox diving
• Practical session on analysing gas

A shallow open water dive may be carried out at the Instructor's discretion. For any SAA EANx diver wanting to continue their Nitrox education, the SAA have a good partnership with IANTD and TDI (Technical Diving International), and the diver is encouraged to talk with either agency. SAA fully recognise all 'tech' qualifications from both these agencies.

SCOTSAC condones EANX diving, but does not run any in-house Nitrox courses. All SCOTSAC divers are encouraged to pursue their Nitrox training with IANTD. Finally as one agency put it, 'if you understood Nitrox, you'd be diving it too'. Gaining a nitrox ticket will help improve your in-water skills, make you think about your diving attitude and equipment, and your diving will be safer and consequently more fun. You may also feel a lot less tired after a brilliant weekend of diving.

	NITROX DIVER BSAC	ADVANCED NITROX DIVER BSAC	COMBINED NITROX DIVER BSAC	NITROX DIVER IANTD	ADVANCED NITROX DIVER IANTD	ENRICHED AIR DIVER PADI	NITROX DIVER SAA
Entry Grade	BSAC Sports Diver (or equivalent) Plus 20 additional dives since qualifying	BSAC Sports Diver (or equivalent) Plus 20 additional dives since qualifying	BSAC Sports Diver (or equivalent) Plus 20 additional dives since qualifying	CMAS 2 Star (or equivalent) Proof of at least 25 dives since qualifying	IANTD Nitrox Diver or IANTD Deep Air Diver (with 16 logged dives after qualifying) or: CMAS 2 Star (or equivalent) (with proof of at least 50 dives with 10 deeper than 30 metres)	PADI Open Water Diver Plus a minimum of 10 additional dives since qualifying or: PADI Advanced Open Water, Advanced Plus (or equivalent)	SAA Club Diver Plus 20 additional dives since qualifying
Pre-Requisites	Current BSAC membership (if relevant) Current BSAC "Fitness to Dive" Certificate (or equivalent)	Current BSAC membership (if relevant) Current BSAC "Fitness to Dive" Certificate (or equivalent)	Current BSAC membership (if relevant) Current BSAC "Fitness to Dive" Certificate (or equivalent)	Minimum 15 years of age (with permission)	Minimum 15 years of age (with permission)	15 years of age or older	Recommendation by DO (Diving Office) to attend the course Current SAA membership Current medical Not pregnant
Qualifications/ Log Book checked and inspected	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Books needed for Course	BSAC Nitrox Diver Student Notes BSAC Nitrox Decompression Tables	BSAC Nitrox Diver Student Notes BSAC Nitrox Decompression Tables	BSAC Nitrox Diver Student Notes BSAC Nitrox Decompression Tables	IANTD Enriched Air Nitrox Student Manual & Workbook	IANTD Advanced EANx Student Manual and Workbook	PADI Enriched Air Diver Manual PADI Nitrox Tables	SAA Decompression System (includes manual and a set of tables) SAA Nitrox Diving Manual
Theory Exam	Yes	Yes	Yes	Yes	Yes	Yes	Yes
Cost	£70 BSAC Schools & Coaching Scheme £25 in Branch (Branch members only)	£100 BSAC Schools & Coaching Scheme £25 in Branch (Branch members only)	£130 BSAC Schools & Coaching Scheme £35 in Branch (Branch members only)	£140	£225	Varies from Centre to Centre	£80 Nationally approved Regional Course
Where can you do this course?	Contact BSAC HQ for details	Contact BSAC HQ for details	Contact BSAC HQ for details	Contact IANTD UK for your nearest facility	Contact IANTD UK for your nearest facility	Contact PADI HQ for details	Contact SAA HQ for details
Mixes qualified Nitrox Diver can purchase	21%, 27%, 32% and 36% EANx	21%, 27%, 32%, 36% and 50% EANx	21%, 27%, 32%, 36% and 50% EANx	All mixes up to and including 40% EANx	All mixes up to and including 50% EANx	All mixes up to and including 40% EANx	21%, 28%, 32%, 36% and 40% EANx