Breathing_gas - Wikiparency

# Breathing gas ## Microsim ### Live player <div class="microsim-player"> <iframe src="https://editor.p5js.org/sciencenibber/full/7FFr9gtTG" width="100%" height="620" frameborder="0" sandbox="allow-scripts allow-same-origin"></iframe> </div> <div class="microsim-fallback"> <img src="Microsims/thumbs/Breathing_gas.png" alt="Breathing_gas microsim poster" style="width:100%;border:1px solid #4445;border-radius:6px;"> <p><em>Live microsim (desktop) · <a href="https://editor.p5js.org/sciencenibber/sketches/7FFr9gtTG">open sketch in the p5.js editor</a></em></p> </div> **Editor URL:** https://editor.p5js.org/sciencenibber/sketches/7FFr9gtTG **Description (100 words):** The Breathing_gas microsim renders a 0-80 m water column on the left with a yellow diver marker driven by a depth slider, and a bouncing-particle "lung snapshot" box on the right whose population scales with absolute pressure (P_total = 1 + depth/10 bar). Four buttons swap the mix between Air, Nitrox 32, Heliox 80/20, and Trimix 18/45; each particle is colored by species (O2 orange, N2 grey, He blue) and helium moves visibly faster than the heavier molecules. Live readouts show partial pressures p_O2, p_N2, and p_He, flag CNS oxygen toxicity above 1.4 bar and [[Nitrogen_narcosis|nitrogen narcosis]] above 3.2 bar, and compute the maximum operating depth (MOD) and equivalent narcotic depth (END) for the selected blend. ```js // ===================================================================== // Breathing_gas.js -- Wikitube microsim // Article: Breathing_gas en.wikitube.io/wiki/Breathing_gas // Room: Helium Pattern: E (particle systems, // animations, kinetic // phenomena) // --------------------------------------------------------------------- // Idea: an interactive depth + lung-box scene that makes Dalton's law // of partial pressures visible as a kinetic snapshot of breathing-gas // molecules. The reader picks one of four standard mixes and drags a // depth slider; the bouncing-particle box on the right shows how the // partial pressures (p_O2, p_N2, p_He) rise with descent. Two safety // thresholds flash when they are exceeded: // // * CNS oxygen toxicity when p_O2 > 1.4 bar // * Nitrogen narcosis when p_N2 > 3.2 bar // // Helium's role is precisely the trick that lets divers go deeper: // swapping nitrogen for helium drops p_N2 (narcosis goes away) without // raising p_O2, and helium's lower molar mass eases respiratory work. // // Canonical equation (Dalton's law of partial pressures): // // p_i = x_i * P_total where P_total = 1 + depth / 10 (bar) // // The four canonical mixes built in: // // * Air O2 21 / N2 79 -- recreational default // * Nitrox 32 O2 32 / N2 68 -- EAN32, extended bottom // * Heliox 80/20 O2 20 / He 80 -- saturation diving, medical // * Trimix 18/45 O2 18 / N2 37 / He 45 -- technical deep diving // // Visual layout (720 x 520 canvas): // * top-left: HUD title + en.wikitube.io/wiki/Breathing_gas subtitle // * top-right: control hints // * left col: ocean depth column 0-80 m, yellow diver marker // * right box: bouncing-particle "lung snapshot" box // - O2 (warm orange) - N2 (cool grey) - He (cool blue) // - particle count scales with absolute pressure // - per-species rms speed scales as 1 / sqrt(m) // (helium is visibly faster than oxygen and nitrogen) // * row 1 ctrl: depth slider, four mix-select buttons // * bottom: P_total, p_O2 / p_N2 / p_He readouts, OxTox / Narcosis // flags, MOD and END // * bottom-right: canonical equation (Dalton's law) // // Conventions (Wikitube Betterfire Standard v0): // * single ARTICLE constant at the top, single quotes // * p5.disableFriendlyErrors = true to keep the editor console clean // * non-ASCII (subscripts, lambda, etc.) lives in COMMENTS ONLY; // every text() string literal is plain ASCII // * Energy-room palette (P5_JS_EDITOR section 4): dark BG, HOT/COLD // species tones, STRUCT grey for nitrogen, TRAJ accent for the diver // * spread only the arrays (HOT, COLD, STRUCT, ...); never ...FG / ...BG // (those are scalar -- prior Heat_transfer / Nuclear_fusion tripwire) // ===================================================================== const ARTICLE = 'Breathing_gas'; const TITLE = ARTICLE.replace(/_/g, ' '); p5.disableFriendlyErrors = true; // ----- Energy room palette (P5_JS_EDITOR section 4, line 165) -------- const BG = 18; const FG = 240; const DIM = [240, 240, 240, 140]; const HOT = [220, 110, 60]; // O2 (warm: life-giving, toxic at high pp) const COLD = [60, 130, 220]; // He (cool blue: noble gas, low density) const STRUCT = [120, 130, 150]; // N2 (neutral grey: the narcosis culprit) const TRAJ = [240, 220, 80]; // diver marker (yellow accent) const SCRATCH = [120, 120, 120, 90]; // grid / tick lines const ALARM = [230, 80, 80]; // threshold-exceeded flash // ----- Standard breathing-gas mixes ---------------------------------- // x[0] = O2 fraction, x[1] = N2 fraction, x[2] = He fraction. const MIXES = [ { name: 'Air', x: [0.21, 0.79, 0.00] }, { name: 'Nitrox 32', x: [0.32, 0.68, 0.00] }, { name: 'Heliox 80/20', x: [0.20, 0.00, 0.80] }, { name: 'Trimix 18/45', x: [0.18, 0.37, 0.45] } ]; // ----- Safety thresholds (Navy / NOAA working-dive limits) ----------- const PO2_MAX = 1.4; // bar, CNS oxygen toxicity onset for working dive const PN2_NARC = 3.2; // bar, perceptible nitrogen narcosis onset // ----- Depth axis and pressure model --------------------------------- // Seawater hydrostatic: P_total [bar] = 1 + depth [m] / 10 const DEPTH_MIN = 0; // m const DEPTH_MAX = 80; // m, well into trimix territory // ----- Visual rectangles (set in setup) ------------------------------ let colX, colY, colW, colH; // ocean depth column let boxX, boxY, boxW, boxH; // lung-snapshot particle box // ----- Controls ------------------------------------------------------ let depthSlider; let mixButtons = []; // ----- Particle system ----------------------------------------------- // Each entry: { x, y, vx, vy, species: 'O2' | 'N2' | 'He', r: pixel radius } let particles = []; const N_BASE = 64; // particle count at 1 atm; scales with pressure let lastDepth = -1; let lastMixIdx = -1; let mixIdx = 0; function setup() { createCanvas(720, 520); pixelDensity(2); textFont('system-ui'); // Ocean depth column on the left. colX = 50; colY = 70; colW = 170; colH = 310; // Lung-snapshot particle box on the right. boxX = 250; boxY = 70; boxW = 450; boxH = 310; // Depth slider directly under the ocean column. depthSlider = createSlider(DEPTH_MIN, DEPTH_MAX, 10, 1); depthSlider.position(colX, colY + colH + 18); depthSlider.size(colW); // Mix-select buttons in a row under the particle box. const bX0 = boxX, bY = colY + colH + 14, bW = 100, gap = 13; for (let i = 0; i < MIXES.length; i++) { const btn = createButton(MIXES[i].name); btn.position(bX0 + i * (bW + gap), bY); btn.size(bW, 24); // Capture i via let (closure) so the click handler picks the right index. const idx = i; btn.mousePressed(() => { mixIdx = idx; rebuildParticles(); }); mixButtons.push(btn); } rebuildParticles(); } function draw() { background(BG); const depth = depthSlider.value(); // Rebuild particles when depth (pressure) or mix changes meaningfully. if (Math.abs(depth - lastDepth) >= 1 || mixIdx !== lastMixIdx) { rebuildParticles(); lastDepth = depth; lastMixIdx = mixIdx; } drawOceanColumn(depth); drawParticleBox(); stepAndDrawParticles(); drawReadouts(depth); drawHUD(); } // ===================================================================== // Particle system: kinetic-theory snapshot of the breathing-gas mix // ===================================================================== // rmsSpeedScale returns a per-species visual speed factor. // Real RMS speed scales as sqrt(T / m_i): at fixed T, v ~ 1 / sqrt(m_i). // Molar masses: O2 = 32 g/mol, N2 = 28 g/mol, He = 4 g/mol. // Normalised so N2 ~ 1.6 px/frame; He is then ~ sqrt(28/4) ~ 2.65 faster. function rmsSpeedScale(species) { if (species === 'He') return 4.25; if (species === 'O2') return 1.50; return 1.60; // N2 } function speciesRadius(species) { // Visual radii roughly reflect kinetic-diameter ordering: // He < N2 ~ O2. Pure visual scaling, not to scale. if (species === 'He') return 3.2; return 4.6; } function rebuildParticles() { particles = []; const depth = depthSlider ? depthSlider.value() : DEPTH_MIN; const P_total = 1 + depth / 10; // bar const N = Math.round(N_BASE * P_total); const mix = MIXES[mixIdx].x; for (let i = 0; i < N; i++) { const r = Math.random(); let species; if (r < mix[0]) species = 'O2'; else if (r < mix[0] + mix[1]) species = 'N2'; else species = 'He'; const v = rmsSpeedScale(species); const ang = Math.random() * Math.PI * 2; particles.push({ x: boxX + 6 + Math.random() * (boxW - 12), y: boxY + 6 + Math.random() * (boxH - 12), vx: Math.cos(ang) * v, vy: Math.sin(ang) * v, species: species, r: speciesRadius(species) }); } } // stepAndDrawParticles updates positions, handles wall reflections, and // draws each particle. Wall reflections at the box edges are perfectly // elastic (no energy loss) so the kinetic snapshot stays at temperature. function stepAndDrawParticles() { push(); noStroke(); for (const p of particles) { // Integrate (Euler, 1 frame). p.x += p.vx; p.y += p.vy; // Reflect off walls of the lung-snapshot box. if (p.x < boxX + p.r) { p.x = boxX + p.r; p.vx = -p.vx; } if (p.x > boxX + boxW - p.r) { p.x = boxX + boxW - p.r; p.vx = -p.vx; } if (p.y < boxY + p.r) { p.y = boxY + p.r; p.vy = -p.vy; } if (p.y > boxY + boxH - p.r) { p.y = boxY + boxH - p.r; p.vy = -p.vy; } // Species color. let col; if (p.species === 'O2') col = HOT; else if (p.species === 'N2') col = STRUCT; else col = COLD; fill(...col); circle(p.x, p.y, p.r * 2); } pop(); } // ===================================================================== // Ocean depth column (left): water column 0-80 m with diver marker // ===================================================================== function drawOceanColumn(depth) { push(); // Column label. noStroke(); fill(...DIM); textSize(11); textAlign(CENTER, BOTTOM); text('water column (msw)', colX + colW / 2, colY - 4); // Depth gradient: shallow blue at top, abyssal at bottom. noStroke(); for (let y = 0; y < colH; y++) { const f = y / colH; const r = lerp(40, 5, f); const g = lerp(80, 18, f); const b = lerp(130, 36, f); fill(r, g, b, 200); rect(colX + 1, colY + y, colW - 2, 1); } // Frame. stroke(...SCRATCH); strokeWeight(1); noFill(); rect(colX, colY, colW, colH); // Depth tick marks every 20 m + labels. textAlign(RIGHT, CENTER); textSize(10); noStroke(); for (let d = 0; d <= DEPTH_MAX; d += 20) { const y = colY + map(d, DEPTH_MIN, DEPTH_MAX, 0, colH); stroke(...SCRATCH); line(colX - 4, y, colX, y); noStroke(); fill(...DIM); text(d + ' m', colX - 6, y); } // Diver marker: tether line from surface plus filled circle. const dy = colY + map(depth, DEPTH_MIN, DEPTH_MAX, 0, colH); stroke(...TRAJ); strokeWeight(1.5); line(colX + colW / 2, colY, colX + colW / 2, dy); noStroke(); fill(...TRAJ); circle(colX + colW / 2, dy, 14); // Depth label next to the diver. fill(...TRAJ); textAlign(LEFT, CENTER); textSize(11); text(depth + ' m', colX + colW / 2 + 12, dy); pop(); } // ===================================================================== // Lung-snapshot particle box (right): frame + species legend // ===================================================================== function drawParticleBox() { push(); // Box label. noStroke(); fill(...DIM); textSize(11); textAlign(CENTER, BOTTOM); text('breathing-gas particles (kinetic snapshot)', boxX + boxW / 2, boxY - 4); // Frame. stroke(...STRUCT); strokeWeight(1.5); noFill(); rect(boxX, boxY, boxW, boxH, 4); // Tiny inline species legend (top-right of the box). const lx = boxX + boxW - 110; const ly = boxY + 14; noStroke(); textSize(10); textAlign(LEFT, CENTER); fill(...HOT); circle(lx, ly, 8); fill(...DIM); text('O2', lx + 10, ly); fill(...STRUCT); circle(lx + 40, ly, 8); fill(...DIM); text('N2', lx + 50, ly); fill(...COLD); circle(lx + 80, ly, 6); fill(...DIM); text('He', lx + 90, ly); pop(); } // ===================================================================== // Readouts: pressures, partial pressures, threshold flags, MOD, END // ===================================================================== function drawReadouts(depth) { const P_total = 1 + depth / 10; // bar const mix = MIXES[mixIdx]; const pO2 = mix.x[0] * P_total; const pN2 = mix.x[1] * P_total; const pHe = mix.x[2] * P_total; const oxTox = pO2 > PO2_MAX; const narc = pN2 > PN2_NARC; // Maximum Operating Depth from current O2 fraction: // MOD = (PO2_MAX / x_O2 - 1) * 10 m const MOD = mix.x[0] > 0 ? (PO2_MAX / mix.x[0] - 1) * 10 : 0; // Equivalent Narcotic Depth: depth at which AIR would deliver this p_N2. // END = (p_N2 / 0.79 - 1) * 10 m const END = (pN2 / 0.79 - 1) * 10; push(); noStroke(); // Anchor the readout block below the particle box. const rx = boxX; const ry = boxY + boxH + 50; // Line 1: total pressure + mix name + composition. fill(...DIM); textSize(12); textAlign(LEFT, BASELINE); text('P_total = ' + nf(P_total, 1, 2) + ' bar depth = ' + depth + ' m', rx, ry); fill(FG); text('mix: ' + mix.name + ' O2 ' + Math.round(mix.x[0] * 100) + '%' + ' N2 ' + Math.round(mix.x[1] * 100) + '%' + ' He ' + Math.round(mix.x[2] * 100) + '%', rx, ry + 16); // Line 3: partial pressures in three colored columns. textSize(12); fill(...HOT); text('p_O2 = ' + nf(pO2, 1, 2) + ' bar', rx, ry + 36); fill(...STRUCT); text('p_N2 = ' + nf(pN2, 1, 2) + ' bar', rx + 140, ry + 36); fill(...COLD); text('p_He = ' + nf(pHe, 1, 2) + ' bar', rx + 280, ry + 36); // Line 4: threshold flags. ALARM color when exceeded; DIM when safe. textSize(11); if (oxTox) fill(...ALARM); else fill(...DIM); text((oxTox ? '[!]' : ' ') + ' OxTox p_O2 > 1.4 bar', rx, ry + 54); if (narc) fill(...ALARM); else fill(...DIM); text((narc ? '[!]' : ' ') + ' Narcosis p_N2 > 3.2 bar', rx + 200, ry + 54); // Line 5: derived operational depths. fill(...DIM); textSize(11); text('MOD = ' + (mix.x[0] > 0 ? nf(MOD, 1, 1) + ' m' : 'n/a'), rx, ry + 72); text('END (air-equivalent narcotic depth) = ' + nf(END, 1, 1) + ' m', rx + 140, ry + 72); pop(); } // ===================================================================== // HUD: title, subtitle, hints, canonical equation // ===================================================================== function drawHUD() { // Top-left: title + Wikitube URL (Betterfire Standard rule 2). noStroke(); fill(FG); textAlign(LEFT, TOP); textSize(22); text(TITLE, 14, 14); fill(...DIM); textSize(12); text('Wikitube microsim . en.wikitube.io/wiki/Breathing_gas', 14, 40); // Top-right: control hints (Betterfire Standard rule 3). textAlign(RIGHT, TOP); textSize(10); fill(...DIM); text('drag depth slider (0-80 m)', width - 14, 14); text('click a button to switch mix', width - 14, 26); text('helium swap -> drops p_N2', width - 14, 38); // Bottom-right: canonical equation (Betterfire Standard rule 4). textAlign(RIGHT, BOTTOM); fill(FG); textSize(13); text('p_i = x_i * P_total [Daltons law]', width - 14, height - 6); } // ===================================================================== // End of Breathing_gas.js -- Wikitube microsim, Helium room, Pattern E. // ===================================================================== ``` ## Links (Wikipedia order)  `14th_CMAS_Underwater_Photography_World_Championship` · `1973_Mount_Gambier_cave_diving_accident` · `1992_cageless_shark-diving_expedition` · `2026_Dhekunu_Kandu_cave_diving_incident` · `8A4-class_ROUV` · `AAI_underwater_revolver` · `ABISMO` · `ADS_amphibious_rifle` · `AIDA_Hellas` · `AIDA_International` · `AN/BLQ-11_Long-Term_Mine_Reconnaissance_System` · `APS_underwater_rifle` · `AP_Diving` · `ASM-DT_amphibious_rifle` · `Activated_carbon` · `Adrian_Biddle` · `Advanced_Open_Water_Diver` · `Advanced_SEAL_Delivery_System` · 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`David_Saint-Jacques` · `Davis_Submerged_Escape_Apparatus` · `Dead_space_(physiology)` · `Death_of_Bradley_Westell` · `Death_of_Steve_Irwin` · `Deborah_Andollo` · `Decima_Flottiglia_MAS` · `Decompression_(diving)` · `Decompression_equipment` · `Decompression_illness` · `Decompression_practice` · `Decompression_sickness` · `Decompression_tables` · `Decompression_theory` · `Deep-sea_exploration` · `Deep-submergence_rescue_vehicle` · `Deep-submergence_vehicle` · `Deep_Drone` · `Deep_diving` · `Deepsea_Challenger` · `Defence_Diving_School` · `Defense_against_swimmer_incursions` · `Dehydration` · `Demand_valve_oxygen_therapy` · [[Density]] · `Deon_Dreyer` · `Department_of_Employment_and_Labour` · `Depth_gauge` · `Desflurane` · `Devrim_Cenk_Ulusoy` · `Dew_point` · `Dewey_Smith` · `Diamond_Reef_System` · `Dick_Rutkowski` · `Distance_line` · `Dive_Xtras` · `Dive_boat` · `Dive_briefing` · `Dive_center` · `Dive_computer` · `Dive_leader` · `Dive_light` · `Dive_log` · `Dive_planning` · `Divemaster` · `Diver's_pump` · `Diver_communications` · `Diver_detection_sonar` · `Diver_down_flag` · `Diver_navigation` · `Diver_organisations` · `Diver_propulsion_vehicle` · `Diver_rescue` · `Diver_training` · `Diver_training_organization` · `Diver_training_standard` · `Diver_trim` · `Divers_Academy_International` · `Divers_Alert_Network` · `Divers_Institute_of_Technology` · `Diversnight` · `Divex` · `Diving_Diseases_Research_Centre` · `Diving_Medical_Advisory_Council` · `Diving_Science_and_Technology` · `Diving_Unlimited_International` · `Diving_activities` · `Diving_air_compressor` · `Diving_bell` · `Diving_chamber` · `Diving_cylinder` · `Diving_disorders` · `Diving_equipment` · `Diving_hazards` · `Diving_helmet` · `Diving_in_Timor-Leste` · `Diving_in_the_Maldives` · `Diving_in_the_Philippines` · `Diving_instructor` · `Diving_mask` · `Diving_medicine` · `Diving_physics` · `Diving_procedures` · `Diving_rebreather` · `Diving_reflex` · `Diving_regulations` · `Diving_regulator` · `Diving_safety` · `Diving_safety_officer` · `Diving_shot` · `Diving_suit` · `Diving_supervisor` · `Diving_support_equipment` · `Diving_support_vessel` · `Diving_team` · `Diving_watch` · `Diving_weighting_system` · `Doing_It_Right_(scuba_diving)` · `Dominic_Landucci` · `Dorothy_Metcalf-Lindenburger` · `Dottie_Frazier` · `Doug_Allan` · `Douglas_H._Wheelock` · `Downline_(diving)` · `Drift_diving` · `Drill_Master_diving_accident` · `Drowning` · `Dry_Combat_Submersible` · `Dry_suit` · `Dust` · `Dust_mask` · `Duty_of_care` · `Dynamic_apnea` · `Dysbaric_osteonecrosis` · `Dysbarism` · `E._Lee_Spence` · `E._Yale_Dawson` · `ENOS_Rescue-System` · `Ear_clearing` · `Eduard_Admetlla_i_Lázaro` · `Edward_D._Thalmann` · `Elastomeric_respirator` · `Electro-galvanic_oxygen_sensor` · `Elisabeth_Kristoffersen` · `Emergency_ascent` · `Emergency_locator_beacon` · `Emergency_oxygen_system` · `Emma_Farrell_(freediver)` · `Emma_Hwang` · `Emphysema` · `Enflurane` · `Environmental_impact_of_recreational_diving` · `Enzo_Maiorca` · `Equivalent_air_depth` · `Equivalent_narcotic_depth` · `Eric_Cheng` · `Ernest_William_Moir` · `Esbjörn_Svensson` · `Escape_breathing_apparatus` · `Escape_trunk` · `Eugenie_Clark` · `European_Diving_Technology_Committee` · `European_Underwater_Federation` · `European_Underwater_and_Baromedical_Society` · `European_respirator_standards` · `Exhaust_gas` · `Explosion` · `FNRS-2` · `FNRS-3` · `Faber_Industrie_S.p.A.` · `Fabien_Cousteau` · `Fatma_Uruk` · `Federación_Española_de_Actividades_Subacuáticas` · `Federazione_Italiana_Attività_Subacquee` · `Felix_Hoppe-Seyler` · `Fenzy` · `Fernando_Garfella_Palmer` · `Finger_Lakes_Underwater_Preserve_Association` · `Finning_techniques` · `Finswimming` · `First_aid` · `Fitness_to_dive` · `Flavia_Eberhard` · [[Fractional_distillation]] · `Francis_P._Hammerberg` · `Francisco_Ferreras` · `François_de_Roubaix` · `Fred_M._Roberts` · `Freediving` · `Freediving_blackout` · `Freeflow` · `Frenzel_maneuver` · `Frogman` · `Frogman_Corps_(Denmark)` · `Fuel` · `Fuerzas_Especiales` · `Fukuryu` · `Full-face_diving_mask` · `Fédération_Française_d'Études_et_de_Sports_Sous-Marins` · `GRUMEC` · `Garrett_Reisman` · `Gary_Gentile` · `Gas_blending` · `Gas_blending_for_scuba_diving` · `Gas_cylinder` · `Gas_mask` · `General_anaesthesia` · `General_anaesthetic` · `George_Bass_(archaeologist)` · `George_F._Bond` · `George_R._Fischer` · `Georges_Beuchat` · `Giovanni_Alfonso_Borelli` · `Global_Explorer_ROV` · `Global_Underwater_Explorers` · `Glossary_of_breathing_apparatus_terminology` · `Glossary_of_underwater_diving_terminology` · `Goldfinder` · `Goldfish-class_ROUV` · `Goran_Čolak` · `Gordon_Smith_(inventor)` · `Graham_Balcombe` · `Graham_Jessop` · `Green_Fins` · `Gregory_Chamitoff` · `Guillaume_Néry` · `Gunter_Schöbel` · `Guy_Garman` · `Guybon_Chesney_Castell_Damant` · `Gyrojet` · `HMS_Challenger_(K07)` · `HMS_Royal_George_(1756)` · `Haenyeo` · `Halcyon_PVR-BASC` · `Halcyon_RB80` · `Haldane's_decompression_model` · `Halogenated_ether` · `Hannes_Keller` · `Hans_Hass` · `Hans_Hass_Award` · `Hawaiian_sling` · `Hazard_analysis` · `Hazmat_diving` · `Hazmat_suit` · `Health_and_Safety_Executive` · `Heat_exhaustion` · `Heckler_&_Koch_P11` · `Heidemarie_Stefanyshyn-Piper` · `Heinke_(diving_equipment_manufacturer)` · `HeinrichsWeikamp` · `Helgoland_Habitat` · `Helicopter_Aircrew_Breathing_Device` · `Heliox` · [[Helium]] · `Helium_analyzer` · `Helium_release_valve` · `Helix_Energy_Solutions_Group` · `Henry_Fleuss` · `Henry_Valence_Hempleman` · `Henry_Way_Kendall` · `Herbert_Nitsch` · `Hervé_Stevenin` · `Hierarchy_of_hazard_controls` · `High-pressure_nervous_syndrome` · `Hillary_Hauser` · `History_of_Diving_Museum` · `History_of_decompression_research_and_development` · `History_of_scuba_diving` · `History_of_underwater_diving` · `Honor_Frost` · `Hopcalite` · `Hot_stab` · `Hugh_Bradner` · `Human_body` · `Human_factors_in_diving_equipment_design` · `Human_factors_in_diving_safety` · `Human_torpedo` · `Humus` · `Hydreliox` · `Hydrocarbon` · [[Hydrogen]] · `Hydrogen_narcosis` · `Hydrostatic_test` · `Hydrox_(breathing_gas)` · `Hyperbaric_evacuation_and_rescue` · `Hyperbaric_medicine` · `Hyperbaric_nursing` · `Hyperbaric_stretcher` · `Hyperbaric_treatment_schedules` · `Hyperbaric_welding` · `Hypercapnia` · `Hyperoxia` · `Hyperthermia` · `Hypocapnia` · `Hypothermia` · `IDA71` · `Ian_Edward_Fraser` · `Ice_diving` · `Ictineu_3` · `In-water_recompression` · `In-water_surface_cleaning` · `Incident_pit` · `Incompetence` · `Index_of_recreational_dive_sites` · `Index_of_underwater_divers` · `Index_of_underwater_diving` · `Industrial_gas` · [[Inert_gas]] · `Inner_ear_decompression_sickness` · `Innes_McCartney` · `Instinctive_drowning_response` · `Internal_combustion_engine` · `International_Association_for_Handicapped_Divers` · `International_Association_of_Nitrox_and_Technical_Divers` · `International_Diving_Regulators_and_Certifiers_Forum` · `International_Diving_Schools_Association` · `International_Life_Saving_Federation` · `International_Marine_Contractors_Association` · `International_Scuba_Diving_Hall_of_Fame` · `International_Space_Station` · `International_Submarine_Escape_and_Rescue_Liaison_Office` · `Interspiro_DCSC` · `Introductory_diving` · `Investigation_of_diving_accidents` · `Iron_lung` · `Isobaric_counterdiffusion` · `Isoflurane` · `Israeli_Diving_Federation` · `Ivan_Tors` · `J._Lamar_Worzel` · `JAGO_(German_research_submersible)` · `JIM_suit` · `Jack_Sheppard_(cave_diver)` · `Jackstay` · `Jacques_Cousteau` · `Jacques_Mayol` · `Jacques_Triger` · `Jagdkommando` · `James_Cameron` · `James_F._Cahill` · `James_Joseph_Magennis` · `James_P._Delgado` · `James_Talacek` · `Jarrod_Jablonski` · `Jason_deCaires_Taylor` · `Jean-Michel_Cousteau` · `Jeanette_Epps` · `Jeffrey_Bozanic` · `Jeffrey_Williams_(astronaut)` · `Jeremy_Hansen` · `Jerónimo_de_Ayanz_y_Beaumont` · `Jessica_Meir` · `Jiaolong_(submersible)` · `Jill_Heinerth` · `Jim_Bowden_(diver)` · `Jim_Jones_(American_football,_born_1935)` · `Joachim_Wendler` · `Job_safety_analysis` · `Jochen_Hasenmayer` · `Joe_Savoie` · `John_Bennett_(diver)` · `John_Bevan_(diver)` · `John_Chatterton` · `John_Christopher_Fine` · `John_D._Craig` · `John_D._Olivas` · `John_Day_(carpenter)` · `John_Deane_(inventor)` · `John_Ernest_Williamson` · `John_Herrington` · `John_Lethbridge` · `John_Mattera` · `John_Morgan_Wells` · `John_Peter_Oleson` · `John_R._Clarke_(scientist)` · `John_Rawlins_(Royal_Navy_officer)` · `John_Scott_Haldane` · `John_Veltri` · `John_Volanthen` · `Johnson_Outdoors` · `Johnson_Sea_Link_accident` · `Jon_Lindbergh` · `Jonathan_Bird` · `Jonathan_Dory` · `Josef_Schmid_(flight_surgeon)` · `Josef_Velek` · `Joseph-Martin_Cabirol` · `Joseph_B._MacInnis` · `Joseph_M._Acaba` · `Joseph_Salim_Peress` · `José_M._Hernández` · `Justin_Brown_(aquanaut)` · `K._Megan_McArthur` · `KOPASKA` · `Kaikō_ROV` · `Karen_Kohanowich` · `Karen_Nyberg` · `Karl_Heinrich_Klingert` · `Karol_Meyer` · `Karst_Underwater_Research` · `Kate_Middleton_(free-diver)` · `Kateryna_Sadurska` · `Kathleen_Rubins` · `Kaşif_ROUV` · `Keith_Jessop` · `Kenneth_William_Donald` · `Kimiya_Yui` · `Kirsty_MacColl` · `Kjell_N._Lindgren` · `Koichi_Wakata` · `Konsul-class_submersible` · `Kronan_(ship)` · `Krzysztof_Starnawski` · `LR5` · `LR7` · `La_Belle_(ship)` · `Lambertsen_Amphibious_Respiratory_Unit` · `Laryngeal_mask_airway` · `Laryngospasm` · `Leigh_Bishop` · `Leni_Riefenstahl` · `Leonardo_D'Imporzano` · `Les_Kaufman` · `Life-support_system` · `Lifting_bag` · `Limpet_mine` · `Line_marker` · `Lionel_Crabb` · `Lipid_pneumonia` · `Liquid_air` · `List_of_Divers_Alert_Network_publications` · `List_of_diver_certification_organizations` · `List_of_diving_environments_by_type` · `List_of_diving_equipment_manufacturers` · `List_of_diving_hazards_and_precautions` · `List_of_legislation_regulating_underwater_diving` · `List_of_military_diving_units` · `List_of_researchers_in_underwater_diving` · `List_of_signs_and_symptoms_of_diving_disorders` · `List_of_wreck_diving_sites` · `Liv_Philip` · `Liveaboard` · `Lockout–tagout` · `London_Diving_Chamber_Dive_Lectures` · `Louis_Boutan` · `Louis_de_Corlieu` · `Low_impact_diving` · `Loïc_Leferme` · `Lubricant` · `Luca_Parmitano` · `Luis_Marden` · `Lyons_Maritime_Museum` · `Lyuba_Ognenova-Marinova` · `MARCOS` · `MSM-1` · `Magnesium_torch` · `Man_in_the_Sea_Museum` · `Mandy-Rae_Cruickshank` · `Marc_Reagan` · `Mares_(scuba_equipment)` · `Margaret_Rule` · `Marine_Commandos` · `Marine_Raider_Regiment` · `Marine_construction` · `Marinejegerkommandoen` · `Mark_Ellyatt` · `Mark_Hulsbeck` · `Mark_IV_Amphibian` · `Mark_M._Newell` · `Mark_T._Vande_Hei` · `Martyn_Farr` · `Mary_Bonnin` · `Mary_Rose` · `Master_Scuba_Diver` · `Master_diver_(United_States_Navy)` · `Matthias_Maurer` · `Maurice_Fargues` · `Maurice_Fernez` · `Maximum_operating_depth` · `McCann_Rescue_Chamber` · `Mechanical_filter_(respirator)` · `Mechanical_ventilation` · `Mechanism_of_diving_regulators` · `Media_diving` · `Medical_prescription` · `Mehgan_Heaney-Grier` · `Membrane_gas_separation` · `Mendel_L._Peterson` · `Mensun_Bound` · `Messenger_line` · `Metabolism` · `Metre_sea_water` · `Michael_Arbuthnot` · `Michael_Barratt_(astronaut)` · `Michael_Board` · `Michael_C._Barnette` · `Michael_Fincke` · `Michael_L._Gernhardt` · `Michael_López-Alegría` · `Michele_Westmorland` · `Middle_ear_barotrauma` · `Milan_Dufek` · `Military_diving` · `Minedykkerkommandoen` · `Minentaucher` · `Mini_Rover_ROV` · `Mir_(submersible)` · `Mission_31` · `Mk_1_Underwater_Defense_Gun` · `Modulated_ultrasound` · `Molecular_sieve` · `Momsen_lung` · `Monitoring_(medicine)` · `Monofin` · `Monty_Halls` · `Moon_pool` · `Morse_Diving` · `Motion_sickness` · `Motorised_Submersible_Canoe` · `Mountaineering` · `Muck_diving` · `Muscle_memory` · `Myriam_Seco` · `Mystic-class_deep-submergence_rescue_vehicle` · `N95_respirator` · `NATO_Submarine_Rescue_System` · `NIOSH_air_filtration_rating` · `NOAA_Diving_Manual` · `NOGI_Awards` · `Namibian_Marine_Corps` · `Nasal_cannula` · `Natalia_Molchanova` · `Nataliia_Zharkova` · `National_Academy_of_Scuba_Educators` · `National_Association_of_Underwater_Instructors` · `National_Board_of_Diving_and_Hyperbaric_Medical_Technology` · `National_Oceanic_and_Atmospheric_Administration` · `National_Speleological_Society` · [[Natural_gas]] · `Nautical_Archaeology_Program` · `Nautical_Archaeology_Society` · `Nautile` · `Nautilus_Productions` · `Naval_Air_Command_Sub_Aqua_Club` · `Naval_Diving_Unit_(Singapore)` · `Naval_Service_Diving_Section` · `Naval_Special_Operations_Command` · `Naval_Submarine_Medical_Research_Laboratory` · `Naval_Support_Activity_Panama_City` · `Navy_diver_(United_States_Navy)` · `Neal_W._Pollock` · `Necker_Nymph` · `Nederlandse_Onderwatersport_Bond` · `Nemrod` · [[Neon]] · `Neox_(TV_channel)` · `Netherlands` · `Neutral_Buoyancy_Laboratory` · `Neutral_Buoyancy_Simulator` · `Neutral_buoyancy` · `Neutral_buoyancy_pool` · `Neutral_buoyancy_simulation_as_a_training_aid` · `Neville_Coleman` · `Newtsuit` · `Nicholas_Mevoli` · `Nicholas_Patrick` · `Nicole_Stott` · `Night_diving` · `Nikonos` · [[Nitrogen]] · [[Nitrogen_narcosis]] · `Nitrous_oxide` · `Nitrox` · `No-limits_apnea` · `Noel_Monkman` · `Non-freezing_cold_injury` · `Non-invasive_ventilation` · `Non-rebreather_mask` · `Nondestructive_testing` · `Nordic_Deep` · `Norishige_Kanai` · `Nuno_Gomes_(diver)` · `Nurse_anesthetist` · `Occupational_safety_and_health` · `Ocean_current` · `Oceanic_Worldwide` · `Octopus_wrestling` · `Offshore_construction` · `Open-water_diving` · `OpenROV` · `Open_Water_Diver` · `Operational_Diving_Division_(SA_Navy)` · `Operations_manual` · `Orinasal_mask` · `Orlan_space_suit` · `Oscar_Gugen` · `Outline_of_recreational_dive_sites` · `Outline_of_underwater_divers` · `Outline_of_underwater_diving` · `Overconfidence_effect` · `Overlearning` · [[Oxygen]] · `Oxygen_compatibility` · `Oxygen_concentrator` · `Oxygen_mask` · `Oxygen_saturation` · `Oxygen_tent` · `Oxygen_therapy` · `Oxygen_toxicity` · `Oxygen_window` · `Panic` · `Paralysis` · `Partial_pressure` · `Pascal_(unit)` · `Pascal_Bernabé` · `Patrick_Musimu` · `Paul_Bert` · `Paul_Hill_(flight_director)` · `Paul_Rose_(TV_presenter)` · `Pearl_hunting` · `Pearling_in_Western_Australia` · `Pedro_Duque` · `Peggy_Whitson` · `Penetration_diving` · `Peppo_Biscarini` · `Performance_Freediving_International` · `Pete_Oxford` · `Peter_B._Bennett` · `Peter_Gimbel` · `Peter_Kreeft_(diver)` · `Peter_Scoones` · `Peter_Throckmorton` · `Philippe_Cousteau` · `Philippe_Diolé` · `Philippe_Tailliez` · `Physiology_of_decompression` · `Pierre-Marie_Touboulic` · `Pierre_Frolla` · `Pierre_Petit_(photographer)` · `Pigging` · `Pilar_Luna` · `Pisces-class_deep_submergence_vehicle` · `Pocket_mask` · `Polespear` · `Police_diving` · `Pony_bottle` · `Porpoise_(scuba_gear)` · `Positive_airway_pressure` · `Potable_water_diving` · `PowerSwim` · `Powered_air-purifying_respirator` · `Powerhead_(firearm)` · `Pressure` · `Pressure_regulator` · `Pressure_swing_adsorption` · `Pressure_washing` · `Priz-class_deep-submergence_rescue_vehicle` · `Professional_Association_of_Diving_Instructors` · `Professional_Diving_Instructors_Corporation` · `Professional_Technical_and_Recreational_Diving` · `Professional_diving` · `Public_safety_diving` · `Pyle_stop` · `QBS-06` · `Queen_Anne's_Revenge` · `Quintana_Roo_Speleological_Survey` · `R-2_Mala-class_swimmer_delivery_vehicle` · `RMS_Lusitania` · `ROV_KIEL_6000` · `ROV_PHOCA` · `RV_Calypso` · `Raid_on_Alexandria_(1941)` · `Ramón_Bravo` · `Randolph_Bresnik` · `Ratio_decompression` · `Rebreather` · `Rebreather_Association_of_International_Divers` · `Rebreather_diving` · `Recreational_Dive_Planner` · `Recreational_dive_sites` · `Recreational_diver_course_referral` · `Recreational_diver_training` · `Recreational_diving` · `Recreational_scuba_certification_levels` · `Reduced_gradient_bubble_model` · [[Redundancy_(engineering)]] · `Reef_Check` · `Reef_Life_Survey` · `Reid_Wiseman` · `Remotely_operated_underwater_vehicle` · `René_Cavalero` · `Rescue_Diver` · `Respirator` · `Respiratory_failure` · `Respiratory_gas_humidification` · `Respiratory_protective_equipment` · `Resuscitator` · `Rex_J._Walheim` · `Ric_Frazier` · `Ricardo_Armbruster` · `Richard_Harris_(anaesthetist)` · `Richard_Pyle` · `Richard_R._Arnold` · `Richie_Kohler` · `Rick_Stanton` · `Risk_assessment` · `Risk_control` · `Risk_management` · `Rob_Stewart_(filmmaker)` · `Robert_A._Barth` · `Robert_Ballard` · `Robert_Boyle` · `Robert_Croft_(diver)` · `Robert_F._Marx` · `Robert_Sheats` · `Robert_Sténuit` · `Robert_Thirsk` · `Robert_William_Hamilton_Jr.` · `Robin_Cook_(American_novelist)` · `Rodney_Fox` · `Ron_Taylor_(diver)` · `Ronald_J._Garan_Jr.` · `Royal_Australian_Navy_School_of_Underwater_Medicine` · `Royal_Engineers` · `Royal_Navy_ships_diver` · `Rubicon_Foundation` · `Rule_of_thirds_(diving)` · `Russian_commando_frogmen` · `Russian_deep_submergence_rescue_vehicle_AS-28` · `Russian_submarine_AS-34` · `Russian_submarine_Losharik` · `SEALAB` · `SEAL_Delivery_Vehicle` · `SJT-class_ROUV` · `SP-350_Denise` · `SPP-1_underwater_pistol` · `SRV-300` · `SS_Commodore` · `SS_Egypt` · `SS_Laurentic_(1908)` · `Safety-critical_system` · `Safety_data_sheet` · `Salt_water_aspiration_syndrome` · `Salvage_diving` · `Samir_Alhafith` · `Sandra_Magnus` · `Sappers_Divers_Group` · `Sara_Campbell` · `Satoshi_Furukawa` · `Saturation_diving` · `Saturation_diving_system` · `Save_Ontario_Shipwrecks` · `Science_of_underwater_diving` · `Scientific_diving` · `Scorpio_ROV` · `Scott_Carpenter` · `Scott_Carpenter_Space_Analog_Station` · `Scott_Kelly_(astronaut)` · `Scuba_Diving_International` · `Scuba_Educators_International` · `Scuba_Schools_International` · `Scuba_cylinder_valve` · `Scuba_diving` · `Scuba_diving_fatalities` · `Scuba_diving_in_the_Cayman_Islands` · `Scuba_diving_therapy` · `Scuba_diving_tourism` · `Scuba_gas_management` · `Scuba_gas_planning` · `Scuba_manifold` · `Scuba_set` · `Scuba_skills` · `SeaKeys` · `SeaPerch` · `Sea_Dragon-class_ROV` · `Sea_Pole-class_bathyscaphe` · `Sea_Research_Society` · `Seabed_mining` · `Seabed_tractor` · `Seafox_drone` · `Seal_(mechanical)` · `Seizure` · `Self-contained_breathing_apparatus` · `Self-contained_self-rescue_device` · `Serena_Auñón-Chancellor` · `Sevoflurane` · `Shadow_Divers` · `Shallow_Water_Combat_Submersible` · `Shannon_Walker` · `Shark_tourism` · `Shayetet_13` · `Shearwater_Research` · `Sheck_Exley` · `Ships_husbandry` · `Sidemount_diving` · `Siebe_Gorman` · `Siebe_Gorman_CDBA` · `Siebe_Gorman_Salvus` · `Silica_gel` · `Silt_out` · `Siluro_San_Bartolomeo` · `Simon_Mitchell` · `Simone_Arrigoni` · `Simone_Melchior` · `Simple_face_mask` · `Single_point_of_failure` · `Sinking_of_MV_Conception` · `Sinking_of_the_Rainbow_Warrior` · `Sinking_ships_for_wreck_diving_sites` · `Situation_awareness` · `Skandalopetra_diving` · `Skill_assessment` · `Smoke` · `Smoke_hood` · `Snorkel_(swimming)` · `Snorkeling` · `Snuba` · `Society_for_Underwater_Historical_Research` · `Society_for_Underwater_Technology` · `Soda_lime` · `Solo_diving` · `Sonar` · `South_African_Underwater_Sports_Federation` · `South_Pacific_Underwater_Medicine_Society` · `Space_Systems_Laboratory_(Maryland)` · `Space_suit` · `Spacecraft` · `Spearfishing` · `Speargun` · `Special_Actions_Detachment` · `Special_Air_Service` · `Special_Air_Service_Regiment` · `Special_Boat_Service` · `Special_Boat_Squadron_(Sri_Lanka)` · `Special_Forces_Command_(Turkey)` · `Special_Forces_Group_(Belgium)` · `Special_Operations_Battalion_(Croatia)` · `Special_Service_Group_(Navy)` · `Special_Warfare_Diving_and_Salvage` · `Spinal_cord` · `Sponge_diving` · `Sport_diving_(sport)` · `Stan_Waterman` · `Standard_diving_dress` · `Standard_operating_procedure` · `Standard_temperature_and_pressure` · `Star_Canopus_diving_accident` · `Static_apnea` · `Steinke_hood` · `Stena_Seaspread_diving_accident` · `Stephanie_Schwabe` · `Stephen_Frink` · `Stephen_Keenan` · `Steve_Chappell` · `Steve_Irwin` · `Steve_Lewis_(diver)` · `Steve_Parish_(photographer)` · `Steve_Squyres` · `Stig_Severinsen` · `Stress_exposure_training` · `Stéphane_Mifsud` · `Sub-Aqua_Association` · `Sub_Marine_Explorer` · [[Submarine]] · `Submarine_Escape_Immersion_Equipment` · `Submarine_Escape_Training_Facility_(Australia)` · `Submarine_Escape_and_Rescue_system_(Royal_Swedish_Navy)` · `Submarine_Products` · `Submarine_Rescue_Diving_Recompression_System` · `Submarine_escape_training_facility` · `Submarine_pipeline` · `Submarine_rescue` · `Submarine_rescue_ship` · `Subskimmer` · `Suction_(medicine)` · `Sunita_Williams` · `Supervised_diver` · `Supplied-air_respirator` · `Surface-supplied_diving` · `Surface-supplied_diving_equipment` · `Surface-supplied_diving_skills` · `Surface_marker_buoy` · `Surfer's_ear` · `Sustained_load_cracking` · `Suunto` · `Swedish_warship_Mars` · `Swietenia_Puspa_Lestari` · `Swimfin` · `Swimming-induced_pulmonary_edema` · `Swimming_at_the_1900_Summer_Olympics_–_Men's_underwater_swimming` · `Sydney_Knowles` · `Sylvia_Earle` · `T1200_Trenching_Unit` · `Tactical_Divers_Group` · `Takuya_Onishi` · `Tamara_Benitez` · `Tanya_Streeter` · `Tara_Ruttley` · `Taravana` · `Task_loading` · `Teaching_method` · `Technical_Diving_International` · `Technical_diving` · `Ted_Eldred` · `Tektite_habitat` · `Teseo_Tesei` · `Testing_and_inspection_of_diving_cylinders` · `Thalmann_algorithm` · `Tham_Luang_cave_rescue` · `The_Darkness_Beckons` · `The_Diver` · `The_Last_Dive` · `The_Silent_World:_A_Story_of_Undersea_Discovery_and_Adventure` · `Theories_of_general_anaesthetic_action` · `Thermal_balance_of_the_underwater_diver` · `Thermal_insulation` · `Thermal_lance` · `Thermodynamic_model_of_decompression` · `Thomas_Marshburn` · `Thomas_Pesquet` · `Tim_Peake` · `Timeline_of_diving_technology` · `Timothy_Creamer` · `Timothy_J._Broderick` · `Timothy_Kopra` · `Tom_Mount` · `Tom_Sietas` · `Torricellian_chamber` · `Towboard` · `Tracheal_tube` · `Trademark` · `Tremie` · `Trevor_Hampton` · `Trevor_Jackson_(diver)` · [[Trimix_(breathing_gas)]] · `Trimix_Scuba_Association` · `Turkish_Underwater_Sports_Federation` · `U.S._Navy_Diving_Manual` · `UNGERIN` · `URF_(Swedish_Navy)` · `USS_Monitor` · `US_Navy_decompression_models_and_tables` · `Umberto_Pelizzari` · `Uncontrolled_decompression` · `Undersea_and_Hyperbaric_Medical_Society` · `Underwater_Archaeology_Branch,_Naval_History_&_Heritage_Command` · `Underwater_Bike_Race` · `Underwater_Construction_Teams` · `Underwater_Demolition_Command` · `Underwater_Demolition_Team` · `Underwater_Escape_Training_Unit` · `Underwater_Hockey_World_Championships` · `Underwater_Orienteering_World_Championships` · `Underwater_Rugby_World_Championships` · `Underwater_Society_of_America` · `Underwater_acoustic_communication` · `Underwater_acoustic_positioning_system` · `Underwater_acoustics` · `Underwater_archaeology` · `Underwater_breathing_apparatus` · `Underwater_computer_vision` · `Underwater_construction` · `Underwater_cutting_and_welding` · `Underwater_cycling` · `Underwater_demolition` · `Underwater_diving` · `Underwater_diving_emergency` · `Underwater_diving_environment` · `Underwater_diving_in_Guam` · `Underwater_domain_awareness` · `Underwater_environment` · `Underwater_exploration` · `Underwater_firearm` · `Underwater_football` · `Underwater_habitat` · `Underwater_hockey` · `Underwater_hockey_in_Australia` · `Underwater_hockey_in_Turkey` · `Underwater_logging` · `Underwater_orienteering` · `Underwater_photography` · `Underwater_photography_(sport)` · `Underwater_rugby` · `Underwater_rugby_in_the_United_States` · `Underwater_search_and_recovery` · `Underwater_searches` · `Underwater_sports` · `Underwater_survey` · `Underwater_target_shooting` · `Underwater_vehicle` · `Underwater_videography` · `Underwater_vision` · `Underwater_work` · `United_Diving_Instructors` · `United_States_Marine_Corps_Combatant_Diver_Course` · `United_States_Marine_Corps_Force_Reconnaissance` · `United_States_Marine_Corps_Reconnaissance_Battalions` · `United_States_Navy_Experimental_Diving_Unit` · `United_States_Navy_SEALs` · `United_States_military_divers` · `Valerie_Taylor_(diver)` · `Valerie_van_Heest` · `Valsalva_maneuver` · `Valve` · `Varying_Permeability_Model` · `Vasa_(ship)` · `Ventilator` · `Venturi_mask` · `Vertical_Blue` · `Victor_Berge` · `VideoRay_UROVs` · `Vintage_scuba` · [[Viscosity]] · `Volatility_(chemistry)` · `WHO_Model_List_of_Essential_Medicines` · `Waage_Drill_II_diving_accident` · `Wall_diving` · `Walter_Steyn` · `Water_polo_cap` · `Water_safety` · `Water_surface_searches` · `Welding` · `Welfreighter` · `Western_Norway_University_of_Applied_Sciences` · `Wet_Nellie` · `Wet_sub` · `Wetsuit` · `Whydah_Gally` · `Wildrake_diving_accident` · `Willard_Franklyn_Searle` · `Willful_violation` · `William_Beebe` · `William_Hogarth_Main` · `William_Paul_Fife` · `William_R._Royal` · `William_Stone_(caver)` · `William_Trubridge` · `Women_Divers_Hall_of_Fame` · `Woodville_Karst_Plain_Project` · `Work_of_breathing` · `World_Health_Organization` · `World_Recreational_Scuba_Training_Council` · `Wreck_diving` · [[Xenon]] · `YMCA_SCUBA_Program` · `Yasemin_Dalkılıç` · `Yuri_Gagarin_Cosmonaut_Training_Center` · `Yves_Le_Prieur` · `Zale_Parry` · `Émile_Gagnan` · `Épaulard` · `Şahika_Ercümen` ## From the vault media library !Breathing gas thumb.png *Breathing Gas — from the vault's own media holdings, placed 2026-07-09. MTN / Wikitube.io original · CC BY-SA 4.0.*  > **Room:** [[Helium]] · **Status:** ✅ shipped ## Overview A breathing gas is a precisely composed mixture of gases supplied for respiration outside the standard sea-level atmosphere. Ordinary air (about 78% nitrogen, 21% oxygen, 1% argon) is the default breathing gas, but altitude, undersea pressure, hyperbaric chambers, anesthesia, neonatal ventilation, and spaceflight all require deliberate composition control. Two physical laws dominate the design: Dalton's law of partial pressures (p_i = x_i · P_total) and Henry's law of dissolved-gas equilibrium. At depth the total ambient pressure rises by one atmosphere every ten meters of seawater, so each constituent's partial pressure scales correspondingly. Above roughly 1.4 bar oxygen partial pressure central-nervous-[[System|system]] oxygen toxicity becomes a hazard, while nitrogen above about 3.2 bar produces narcosis. To extend the depth envelope divers substitute helium for some or all of the nitrogen — heliox (He/O2) or trimix (He/N2/O2) — because helium is non-narcotic, far less soluble in lipid tissue, and lower in molecular mass, which eases respiratory work. Heliox also serves [[Medicine|medicine]]: an 80/20 He/O2 blend reduces airway resistance and turbulence in croup, severe asthma, and post-extubation stridor. Recreational divers use nitrox (oxygen-enriched air, typically EAN32 or EAN36) to lengthen no-decompression bottom time. Mission-critical operating envelopes are bracketed by the maximum operating depth (MOD = (p_O2_max / x_O2) − 1 atm), the equivalent narcotic depth (END), and the partial-pressure decompression model first formalized by John Scott Haldane in 1908. ## See also - Room hub: [[Helium]] - p5.js Editor conventions: P5 JS EDITOR - Wiki root: MAIN --- *Scaffolded by `generative-microsim` from row 71 of the Helium sheet on 2026-05-12T05:49:24Z.*   *Built to the [[WT!P5_js_Microsim_Master_Class|p5.js Master Class]].*  ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Breathing_gas) : [Wikitube](https://en.wikitube.io/wiki/Breathing_gas) ## Previous hub tags Tree parent: [[Oxygen]]. Legacy hubs: none. --- *Sources: 1 legacy note. Minted wave 1, 2026-07-30 (v1.6 order).*