Speaking as a SCUBA diver, the equipment is not designed to handle high airflow (such as you need when working hard on a bicycle), so even if the air tank itself wasn’t a problem you’d need, at a minimum, a heavily-adjusted second-stage (the one with the mouthpiece) regulator. Possibly a different regulator set altogether. On the other hand, one of the design considerations of a second-stage reg is that the purge valve needs to resist water pressure, including the pressure of swimming; air would generally not have that problem (and you probably wouldn’t have any need for a purge anyhow).
Even basic filter masks can cut down on particulate air pollution by a lot. I’ve spent some time in places with truly horrific air quality—the kind that makes LA seem clear and fresh-smelling—and a lot of people wear something over their face, even just a strip of cloth, when they go out (and sometimes also at night or even all the time). I don’t know how practical they’d be at filtering out anything likely to cause headaches in traffic, and they’re not terribly comfortable to wear, but it might be an option. Of course, in the US, the most common reason you see everyday people wearing something like that is if they’re sick and don’t wish to spread germs from their breath / sneezes, so people may be reluctant to shake your hand...
Speaking as a SCUBA diver, the equipment is not designed to handle high airflow (such as you need when working hard on a bicycle), so even if the air tank itself wasn’t a problem you’d need, at a minimum, a heavily-adjusted second-stage (the one with the mouthpiece) regulator. Possibly a different regulator set altogether. On the other hand, one of the design considerations of a second-stage reg is that the purge valve needs to resist water pressure, including the pressure of swimming; air would generally not have that problem (and you probably wouldn’t have any need for a purge anyhow).
Even basic filter masks can cut down on particulate air pollution by a lot. I’ve spent some time in places with truly horrific air quality—the kind that makes LA seem clear and fresh-smelling—and a lot of people wear something over their face, even just a strip of cloth, when they go out (and sometimes also at night or even all the time). I don’t know how practical they’d be at filtering out anything likely to cause headaches in traffic, and they’re not terribly comfortable to wear, but it might be an option. Of course, in the US, the most common reason you see everyday people wearing something like that is if they’re sick and don’t wish to spread germs from their breath / sneezes, so people may be reluctant to shake your hand...