It would be realistic and nice to see polluted enviroments. I wanted to give my word about this so...
There could be many ways of pollution :
Soil :
Radiation from meltdowns/nukes turning nearby blocks into poisonous ones that spreads slowly (like ICBM ones)
Desertification [over-usage of high rank crops without fertilizers], turning dirt/grass into sand
Atmoshpere :
Radiation from meltdowns/nukes turning whole chunk air poisonous (People could build a geiger counter that works similar to ThaumCraft Vis/Taint aura detector)
Greenhouse gases (From burning stuff), which heats up nearby chunks (Works smilar to radiation), making less stuff grow there and even damage entities if it is on a critical level.
Water :
Radiation from meltdowns/nukes turning whole water into chunk poisonous on contact (Atmosphere and water radiation levels are shared). Fish are less common and they are poisonous.
Water on polluted enviroment will become acid if greenhouse gases are on a critic level, severely damaging anything that comes on contact. (Items dropped will be destroyed)
Hazmat suit should effectively protect players from those damages, but they will stop protecting them once either radiation or greenhouse gases achieve critical levels.
Radiation will slowly decrease (or increase if there are many Uranium ores/blocks in chunk)
greenhouse gases will decrease according to plants on chunk (leaves, sugar canes, wheat, crops... etc)
To Thread Owner : E ai tudo bom? É raro ver alguem que fale portugues por aqui =)