IDK where you were riding… 10 year cycle courier veteran from Boston here with my own anecdotal experience. This could very well be a personal health thing with you. Never had any issues related to the fumes in my throat, or heard of any related issues within the messenger community. If you told me over time that the fumes have a negative impact on healh I’d believe it, but I probably wouldn’t listen to a commuter who rode a tiny fraction of the urban cycling I’ve done personally. I’d be very interested to see a study on long term bike messengers.