In the United States, the vast majority of carbon monoxide released into the atmosphere comes from vehicles and other gas-burning equipment, but fires also contribute.
在美国，释放进入大气层的主要一氧化碳的来源于车辆与燃气设备，火也是致使因素之一。
2
Tilling also releases carbon dioxide from the soil into the atmosphere. No-till keeps carbon in the soil and avoids the release of heat-trapping gases from motorized equipment.
耕作还会将土壤中的二氧化碳释放到大气中，而免耕能够保持住土壤中的碳，并且避免机械设备释放吸热气体。
3
Workers who remove the metals often have no protective equipment and breathe in high levels of toxic chemicals, which are then released into the atmosphere.