Uncertain if this means anything to you - but I live in Southern California. I'm 55 years old and have lived with SMOG everyday of my life. I admit, it has gotten better because California has some very stiff, strong controls in place about emissions and polutants one reason why gas in my state is the highest in the US (regular is about $3.35/ga). You just have to deal with it. I generally ride early or preferably late in the day when the breeze comes up. Uncertain is you get an afternoon breeze where you live. Like anything is SMOG is bad, best to come indoors and do a spin class, if light, use moderation, don't push as hard. Even light exercise is better than none.

Sad to see SMOG is almost everywhere now. Such as life...