Psst, hey professor Prius...

When talking about pollution, industrial waste and automotive exhaust are generally what's pictured, at least by the media but what over a million people in Taiwan vowed to do might be the most effective environmental change yet.

They became herbivores.

Stay with me. According to the Union of NoMeatNoHeat*, that will reduce Taiwan's carbon emissions by 1.5 million tons, provided they stick to said oath.
In a 2006 report by the Food and Agriculture Organization of the U.N.†, "Global meat production is projected to more than double from 229 million tonnes in 1999/2001 to 465 million tonnes in 2050, while milk output is set to climb from 580 to 1043 million tonnes." 18% more CO2 than the automotive sector.
But that's not the worst of it, because "...the livestock sector accounts for 9 percent of CO2 deriving from human-related activities, but produces a much larger share of even more harmful greenhouse gases. It generates 65 percent of human-related nitrous oxide, which has 296 times the Global Warming Potential (GWP) of CO2. Most of this comes from manure."
Not only that, according to the National Resources Defense Council••, "In 1996 the Centers for Disease Control established a link between spontaneous abortions and high nitrate levels in Indiana drinking water wells located close to feedlots."
"High levels of nitrates in drinking water also increase the risk of methemoglobinemia, or "blue-baby syndrome," which can kill infants."
The (undated) NRDC report says that 70 percent of antibiotics in the US go to agriculture, at a rate of about 24 million tons per year. Producing a rise in resistant bacteria.
Hydrogen sulfide emissions wafting from large hog farms killed 19 people in 1998, according to the National Institute of Health.
I could go on but I encourage you to follow the links and read the rest for yourself.

As a side note, the most common chemical fertilizer, such as were (allegedly) used in the OKC bombing are nitrate based and often end up blowing on the wind, since "modern farming" offers no topsoil retention. Thus, the timing of the dustbowl.
A 2008 UN report encourages a return to "Conservation Agriculture," as a more environmentally responsible method.

Thai resolution
*http://english.rti.org.tw/Content/GetSingleNews.aspx?ContentID=59093

Food and Agriculture Org. of the U.N.
† http://www.fao.org/newsroom/en/news/2006/1000448/index.html

National Resources Defense Counsel
•• http://www.nrdc.org/water/pollution/ffarms.asp

Mood music - The little man by Alan Jackson