| ARGON | The name of this third most abundant gas in the Earth's atmosphere means 'inactive' (5) |
| NITROGEN | The most abundant gas in the atmosphere (8) |
| NITRO | Prefix with gen that is the most abundant gas in our atmosphere |
| RIGID | Of an airship or dirigible, having a shape maintained by an internal framework rather than the pressure of gas in the envelope (5) |
| OZONE | Gas in the endangered layer of the atmosphere |
| LIBYA | Worked ably around this third country (5) |
| MARIE | Horse circles this third woman (5) |
| BASIL | Cooked slab has this third flavouring (5) |
| ETHER | There's some gas in the jet he refuelled (5) |
| OXYGEN | Accounting for 65 per cent of the mass of the human body, the third-most abundant element in the universe, atomic number eight (6) |
| FILLS | Puts gas in the tank |
| ALUMINIUM | Third most abundant element in the earth's crust, and the most abundant metal (9) |
| CARBONDIOXIDE | Colourless, odourless gas in the earth's atmosphere originally called fixed air (6,7) |
| SNOW | Precipitation in the earth's atmosphere in the form of six-sided ice crystals |
| AIRWAY | A passage for the gases in the Earth's atmosphere to enter and exit the lungs (6) |
| ASH | Fraxinus excelsior, the third most abundant tree in Britain |
| NITROUS | This oxide, the result of industry and a component of automobile exhaust, is considered to be a trace gas in the atmosphere. |
| PNEUMOTHORAX | A collection of air or gas in the pleural cavity of the chest between the lung and the chest wall |
| SEAWEED | Major source of oxygen in the earth's atmosphere |
| SOUTHSEVENSTEPS | "Aye, the treasure be heavy, so flex yer biceps! With this third clue, turn right and go ___" |
