Pollution Control in City of 1900?

For one thing, go green! Seriously, planting trees helps reduce pollution, so try to plant as many as you can and they should work to lower pollution.

You should try sending your trash to your neighbours, instead of collecting it in your landfills. That means you have one less source of pollution to worry about (and a very big one at that - the area around landfills become very polluted and the land value plummets).

Also, see if you can't get your industry to become more high-tech. I'm not sure if this is possible without environmental ordinances, but apart from that you need a high EQ (which comes with a lot of education). Maybe if you just got the EQ, the game will forgive no ordinances because they don't even exist yet.

Finally, try to reduce traffic, and obviously, don't make deals to host a nuclear waste plant =P

Source: 10 years of experience

You can look here for details.

One thing I've always done is place the high-polluting areas & buildings near an edge or corner of the map - and then surround them with 3-5 blocks thick of trees or parks.

This ensures that a half (or 3 quarters if in the corner) of pollution is shoved off to the neighbouring cities (out of sight, out of mind- right?) and the trees make sure the pollution that is in the city is pretty much reduced to that area.