Air quality is part of the passenger experience.
Temperature and comfort are only part of what passengers expect from a modern HVAC system. The quality of the air they breathe matters too.
Cleanair brings together air distribution, advanced filtration and active purification in a flexible, multistage approach designed specifically for rail. Combined, these technologies remove more than 99% of airborne contamination inside passenger compartments, helping create cleaner, healthier and more comfortable onboard environments.
Integrated sensing technology and software add real-time visibility into onboard air quality, including AQI, CO₂, PM10, PM2.5 and VOC levels, providing operators and passengers with greater transparency throughout the journey.
Cleanair addresses onboard air quality through three complementary dimensions: how air moves through the passenger compartment, how particles are filtered and how remaining contaminants are actively treated.
Cleaner air, engineered at every stage
Cleanair addresses onboard air quality through three complementary dimensions: how air moves through the passenger compartment, how particles are filtered and how remaining contaminants are actively treated.
DISTRIBUTION
Optimized fresh air intake and air distribution architecture help improve ventilation throughout the passenger compartment. Air is supplied from the ceiling and extracted at floor level, creating a controlled downward airflow designed to limit recirculation between passenger zones and support more effective air renewal.
This ceiling-to-floor airflow directs fresh air downward while limiting mixing between passenger rows, supporting more consistent air renewal across the compartment. The system also balances fresh air and return air through an optimized air mix, prioritizing fresh air during sanitation periods while maintaining thermal comfort. Combined with advanced filtration and active purification, this distribution architecture contributes to removing more than 99% of airborne contamination inside passenger compartments.
FILTRATION
Cleanair combines Long Life Filters and electrostatic filtration technologies designed to capture fine particles and aerosols from the HVAC airflow.
High-efficiency filtration supports cleaner air inside passenger compartments while technologies such as Merak's Long Life Filter can last up to four times longer than conventional filters, helping reduce replacement frequency, maintenance requirements and operating costs.
The Long Life Filter is classified ePM10 60% according to ISO 16890, delivering up to two times better filtration efficiency than a standard commercial panel filter while maintaining a comparably low pressure drop of 22 to 88 Pa. Rated for up to 100% operating moisture and carrying an HL3 fire and smoke classification per EN 45545-2 R5, it is built for demanding rail conditions. Fully customizable in width, height and depth, it can be fitted as a drop-in replacement into almost any new or existing HVAC unit.
PURIFICATION
Cleanair combines purification technologies including UV-C irradiation, electric field technologies and ionization to act on airborne contaminants within the HVAC airflow. Depending on the configuration, these technologies help neutralize pathogens and reduce bacteria, viruses, VOCs and other unwanted compounds, adding an active purification stage.
Purification is available in complementary configurations tailored to fleet needs. UV lamps, offered in “High Intensity” and “Extended Exposure” versions, irradiate the filter surface and airflow to kill viruses and bacteria, with either version selectable to balance exposure time against irradiation intensity. A second pathway uses electric field ionization technology to actively neutralize pathogens within the airflow, complementing rather than replacing filtration. Together, these technologies work alongside real-time sensing of AQI, CO2, PM10, PM2.5 and VOC levels.
RETROFIT YOUR FLEET
BETTER ONBOARD AIR QUALITY DOESN’T REQUIRE NEW VEHICLES.
Cleanair technologies can be integrated into existing railway HVAC systems to improve air distribution, filtration, purification and air quality monitoring without replacing complete units. Upgrades can be engineered around existing equipment and integrated during scheduled fleet modernization or overhaul programs, helping extend system service life while improving onboard air quality and controlling lifecycle costs. As part of Naturail, Cleanair turns retrofit into an opportunity to bring today's fleets closer to tomorrow's passenger expectations.
SUSTAINABLE, FULL-SYSTEM RAILWAY HVAC SOLUTIONS
As part of Naturail, Cleanair works within a broader approach to railway HVAC modernization — three complementary technologies, one direction: moving railway HVAC forward.
Naturail
The modular approach to sustainable railway HVAC modernization - new build and retrofit.
Greenair
Lower-impact climate control wih natural refrigerants
Smartair
Brings secure-by-design control, intelligent monitoring and predictive maintenance