I have been trying to understand when air pollution actually began and it has led me into a deep rabbit hole. Some people say it started during the Industrial Revolution while others say it began way earlier. I noticed that even ancient records talk about smoke filled air and people struggling with thick smog. It surprised me because I always thought air pollution was a modern issue. I keep reading about coal burning workshops and old metal forges that produced dark fumes. It makes me wonder how people dealt with this without any kind of filter or purifier. Today we use machines and masks to reduce exposure but they had nothing at all. I am curious if early pollution had long lasting effects or if nature recovered faster back then. I also wonder how experts measure old pollution levels today. If anyone has knowledge or sources that explain the earliest forms of air pollution please share them. I really want to understand how far back this problem goes 
From what I have studied air pollution goes back thousands of years because humans used fire for cooking and metal work. Those early fires produced smoke that filled small communities and created unhealthy breathing spaces. It was not industrial level pollution but it still caused problems in crowded areas. Some old writings even describe blackened walls due to indoor smoke. I think people underestimated how much impact simple fire use had on the environment.
The big turning point was when large factories began running nonstop during the Industrial Revolution. Huge smoke stacks created thick clouds that settled over entire towns. Workers often walked through dark heavy air every day. There were no real safety rules at that time. Many historians believe this was the moment when air pollution became a global scale concern.
I read a study that said ancient Rome had issues with air quality because they used burning oil and wood for nearly everything. The smoke built up during winter months. Researchers found traces of old pollutants in ice cores and soil layers. It is interesting that modern science can detect something that happened so long ago 
This helps a lot I did not know about ice core data
I teach environmental science and one thing we always explain is that pollution did not start suddenly. It grew slowly as human population and technology expanded. Even small villages created smoke filled zones when everyone burned wood at the same time. The difference today is scale and density. Modern pollution is far more concentrated and persistent.
Some historians think air pollution became noticeable the moment humans learned how to control fire. That sounds extreme but fire produces smoke and smoke changes the air. If people gathered in caves or huts the smoke would remain inside for a long time. It probably caused respiratory problems but people accepted it as normal life.