Most Blue-Collar work takes place on a site with bad air quality. As such your lungs have grown accustomed to the strain of breathing in smoke, fumes or exhaust. You have advantage on Saving throws against chemical or gas effects and attacks. When holding your breath you gain an additional 4 rounds of air before suffocating.
Whenever you attempt to conceptualize a repair or an upgrade to a vehicle, you know of the needed materials and where to find them, but dependent on the materials or what they will be used for, the DM may rule their rarity/difficulty when it comes to obtaining them. Additionally whenever you attempt to fix a vehicle, make an upgrade or an addition, you have advantage on the ability check being made, and it takes half the time and materials required.
You gain proficiency in any combination of three skills or tools of your choice.