Motor vehicle cabin air improvement system

A motor vehicle 10 includes an air improvement system configured to pump air through a reservoir 2 containing an algal culture. Gases released from the culture are transmitted into a passenger cabin of the vehicle. The system may comprise an in-cabin CO2 sensor and/or an ambient air CO2 sensor and may recirculate cabin air through the reservoir or draw fresh air through the reservoir prior to delivery to the cabin. The reservoir ideally comprises one or more ducts 6 provided beneath one or more selectively transparent body panels, the panels being opaque when the system isnt needed and transparent in use to allow natural light to reach the culture. Artificial light may also be used. Algal growth is ideally supported by a nitrogen source such as urea received from a diesel exhaust fluid tank of a selective catalytic reduction exhaust treatment system of the vehicle. Ideally the reservoir comprises a tank 4 that can be replaced during vehicle servicing to replenish/replace the algal culture. The system can maintain driver alertness by ensuring that CO2 concentration in the vehicle cabin remains below 1000ppm. An enclosed water impermeable container containing dehydrated algae and nutrients for algal growth is also claimed.