I have only lived here for a few years but I used to live in downtown Worcester and would walk all over the center of the city and down to UMass on Lake Ave and I never once got a sense of polluted air or "stinky" emissions beyond what you can notice from cars when walking along a busy street.

There is an air quality measuring device that the state owns located on Summer St just next to 290 in downtown Worcester. The data is freely available on a number of websites, but this one displays it nicely: https://aqicn.org/city/usa/massachusett/worcester/summer-st/

If you scroll down you can see historic PM2.5, PM10, O3, NO2, SO2, and CO pollution patterns.

I'm not sure where you're moving from, but the northeast generally has cleaner air than a lot of the country. For instance, people often think of NYC as having very polluted air but even in Manhattan and the dense industrial areas in Northern NJ, the air is much cleaner than places like Chicago, Houston, LA--even St. Louis, Atlanta, Indiana, etc.

I don't know how sensitive you are but I feel like unless you were next door to the interstate or some industrial site, you should be fine here.

Sweet smell of marijuana is all over Worcester :)-

Having grown up near Saint Gobain, no it does not stink up the area. The two large iconic smokestacks are dormant. They are remnants of the old Norton Factories, which was acquired by Saint Gobain.

The only two really major sources of bad air (outside of cars) that come to mind are the wheelabrator plant and the water treatment plant, both are along route 20 on the southern border of the city.

Perhaps this: https://www.epa.gov/risk/region-1-risk-assessment-contacts

the air quality here is quantifiably bad, especially compared to other parts of Mass. I never notice it when I’m here but on days that it rains and when i get off the train from Boston it genuinely makes me gag. not in like a “it smell bad” way but just like an immediate unexplained nausea kinda way. At least for me personally. From what i know there’s a fair bit of factory air pollutant, auto shops have gotten in trouble for improper waste disposal, certain areas have VERY few trees (i have approximately 2 trees on my street and both are less than 8ft tall) and the trash/recycling collectors throw bags around and let trash fill the streets. It’s not the worst city but it aint exactly a nature preserve.