Nitrous oxide (N2O), a relatively long-lived gas, has increased in atmospheric concentration due mainly to agriculture.
Nitrate (NO3-) and ammonia (NH4+) are used as fertilizers.
Bacteria convert a small amount of this nitrate and ammonia into the form of nitrous oxide.
Internal combustion engines also produce nitrous oxide.
Internal combustion engines
Caused by nitrogen combines with oxygen in the air while the burning of fuel