A nitrous oxide detector, comprising a gas sensor having: a measurement chamber for receiving ambient gas to be measured; an optical source for emitting radiation in the measurement chamber; a radiation detector sensitive to radiation emitted by the optical source, the radiation being configured to be detected by the radiation detector following passage through the measurement chamber; and the radiation detector being configured to measure occurrence of nitrous oxide (N 2 O) in the gas being measured; the gas sensor comprising: a diffusion layer, the diffusion layer being configured to allow diffusion of ambient gas into and out from the measurement chamber, and the diffusion layer comprising means for preventing diffusion of carbon dioxide (CO 2) in the ambient gas into the measurement chamber, wherein the diffusion layer comprises at least one absorbent being consumed by absorbing carbon dioxide (CO 2) and requiring regular replacement, the nitrous oxide detector further comprising: processing means for receiving measurements of the occurrence of nitrous oxide (N 2 O) from the gas sensor; the processing means being configured to generate a signal when the measurements of the occurrence of nitrous oxide (N 2 O) exceed a predetermined threshold, means for determining a time of operation that has elapsed following a replacement of the diffusion layer, and means for generating a signal representing a requirement for replacing the diffusion layer when the time of operation exceeds a second predetermined time. a measurement chamber for receiving ambient gas to be measured; an optical source for emitting radiation in the measurement chamber; a radiation detector sensitive to radiation emitted by the optical source, the radiation being configured to be detected by the radiation detector following passage through the measurement chamber; and the radiation detector being configured to measure occurrence of nitrous oxide (N 2 O) in the gas being measured; the gas sensor comprising: a diffusion layer, the diffusion layer being configured to allow diffusion of ambient gas into and out from the measurement chamber, and the diffusion layer comprising means for preventing diffusion of carbon dioxide (CO 2) in the ambient gas into the measurement chamber, wherein the diffusion layer comprises at least one absorbent being consumed by absorbing carbon dioxide (CO 2) and requiring regular replacement, the nitrous oxide detector further comprising: processing means for receiving measurements of the occurrence of nitrous oxide (N 2 O) from the gas sensor; the processing means being configured to generate a signal when the measurements of the occurrence of nitrous oxide (N 2 O) exceed a predetermined threshold, means for determining a time of operation that has elapsed following a replacement of the diffusion layer, and means for generating a signal representing a requirement for replacing the diffusion layer when the time of operation exceeds a second predetermined time. a diffusion layer, the diffusion layer being configured to allow diffusion of ambient gas into and out from the measurement chamber, and the diffusion layer comprising means for preventing diffusion of carbon dioxide (CO 2) in the ambient gas into the measurement chamber, wherein the diffusion layer comprises at least one absorbent being consumed by absorbing carbon dioxide (CO 2) and requiring regular replacement, the nitrous oxide detector further comprising: processing means for receiving measurements of the occurrence of nitrous oxide (N 2 O) from the gas sensor; the processing means being configured to generate a signal when the measurements of the occurrence of nitrous oxide (N 2 O) exceed a predetermined threshold, means for determining a time of operation that has elapsed following a replacement of the diffusion layer, and means for generating a signal representing a requirement for replacing the diffusion layer when the time of operation exceeds a second predetermined time. processing means for receiving measurements of the occurrence of nitrous oxide (N 2 O) from the gas sensor; the processing means being configured to generate a signal when the measurements of the occurrence of nitrous oxide (N 2 O) exceed a predetermined threshold, means for determining a time of operation that has elapsed following a replacement of the diffusion layer, and means for generating a signal representing a requirement for replacing the diffusion layer when the time of operation exceeds a second predetermined time.