Acid rain Acid rain Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals and infrastructure. Acid rain is caused by emissions of sulphur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Some governments have made efforts since the 1970s to reduce the release of sulphur dioxide and nitrogen oxide into the atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes, and sulphur dioxide
Oil sands pyrene, and benzo(a)pyrene) and that these emissions had been previously unreported. The Alberta government computes an Air Quality Health Index (AQHI) from sensors in five communities in the oil sands region, operated by a "partner" called the Wood Buffalo Environmental Association (WBEA). Each of their 17 continuously monitoring stations measure 3 to 10 air quality parameters among carbon monoxide (CO), hydrogen sulfide (), total reduced sulfur (TRS), Ammonia (), nitric oxide (NO), nitrogen dioxide (), nitrogen oxides (NO), ozone (), particulate matter (PM2.5), sulfur dioxide (), total hydrocarbons (THC), and methane/non-methane hydrocarbons (/NMHC). These AQHI are said to indicate 'low