Advanced technologies to improve air quality in indoor environments

Indoor air quality (IAQ) is essential for maintaining health and overall well-being. Chirag Kataria, an independent indoor air quality consultant, discusses how employing molecular filtration, UV technologies, and customised ventilation solutions can mitigate pollutants. These ensure safer environments in offices, schools, and healthcare facilities.

Filtration technologies are vital in mitigating infectious disease spread within indoor environments. These technologies help maintain healthier indoor air, reduce transmission risk, and contribute to public health by capturing and neutralising airborne pathogens. Integrating multiple filtration methods provides a comprehensive approach to enhancing indoor air quality and protecting against infectious diseases.

Here is an in-depth understanding of air filtration technologies that reveal their functions and impacts on indoor air quality and infection control. High-efficiency particle air (HEPA) filters, which capture 99.97 percent of particles as small as 0.3 microns, are highly effective at removing dust, pollen, mould spores, and various bacteria and viruses. Common in healthcare settings, clean rooms, and residential cleaners, HEPA filters play a vital role in reducing airborne transmission of infectious agents.

Ultraviolet Germicidal Irradiation (UVGI) systems use UV-C light to inactivate microorganisms by damaging their DNA or RNA. They are especially valuable when paired with standard filtration. UVGI enhances pathogen control by neutralizing any infectious agents that bypass the filters, making it ideal for sterile air requirements in healthcare and HVAC systems. Activated carbon filters add another layer by adsorbing gases, volatile organic compounds (VOCs), and odours, which, while not directly targeting pathogens, contribute to improved air quality and can indirectly support immunity.

Electrostatic precipitators charge particles, capturing a range of particle sizes, including ultrafine particles that may carry infectious agents. Similarly, photocatalytic oxidation (PCO) combines UV light with a catalyst to break down pollutants and microorganisms. It improves air quality. Ionisation technologies, such as bipolar ionisation, release ions that bind to and neutralise pathogens and are used in commercial buildings for pathogen reduction.

Thanks to their ultra-thin fibre networks, nanofiber filters capture microscopic particles, including viruses. They are frequently used in personal protective equipment and HVAC systems. Filters with antimicrobial coatings further prevent microbial growth, reducing contamination risk and extending filter longevity.

Combining these technologies can create highly effective purification systems; a multi-stage setup might include a pre-filter, HEPA filter, activated carbon filter, UVGI, and bipolar ionization or PCO. These integrated approaches can significantly enhance air quality and infection control in healthcare, commercial, and residential settings.

UV technology for disinfection in HVAC systems

The integration of UV technology into HVAC systems has become a key focus in enhancing disinfection and air quality, especially in response to the pandemic. Among the latest innovations are advanced UV-C lamps, which feature higher output and longer lifespans, improving their effectiveness in inactivating microorganisms. Low-mercury versions of these lamps reduce environmental impact while maintaining high disinfection efficacy.

The development of UV-C LEDs has added another layer of innovation. They offer energy-efficient operation and longer service life compared to traditional mercury-vapor lamps. Their compact design makes them versatile, enabling seamless integration into various HVAC system components. Hybrid systems have also emerged, combining UV-C technology with HEPA or activated carbon filters to deliver comprehensive air purification. Some systems improve disinfection by using electrostatic precipitators, which charge particles before exposure to UV-C light, making it easier to inactivate microorganisms.

Reflective materials inside HVAC ducts further optimise UV-C performance by distributing the light more evenly, ensuring consistent disinfection across the airflow. Integration with building management systems (BMS) allows for automated control of UV-C systems based on air quality data, occupancy, and other parameters. These features allow for timely maintenance and automated operation through building management systems, ensuring efficiency and energy savings.

Additionally, portable UV-C units have become valuable tools for flexible disinfection needs. Portable units can be deployed in specific areas or rooms where additional disinfection is needed, offering flexibility in managing air quality. Together, these advancements underscore the growing importance of UV technology in creating safer and healthier indoor environments.

IAQ solutions for offices, schools and healthcare facilities

Tailoring IAQ solutions to specific environments involves identifying the primary pollutants and implementing targeted strategies to address them. By using a combination of advanced filtration, ventilation, UV technology, and real-time monitoring, healthy and safe indoor environments can be created for offices, schools, and healthcare facilities. Regular maintenance and the use of low-emission materials further enhance the effectiveness of these IAQ solutions.

In offices, common pollutants include volatile organic compounds (VOCs) from equipment, furnishings, and cleaning products; carbon dioxide (CO2) from human respiration; particulate matter from HVAC systems and outdoor air; and biological contaminants like mould and bacteria.

• IAQ solutions for offices involve using advanced filtration systems, such as HEPA or MERV 13 filters, to capture fine particles and allergens. Activated carbon filters help adsorb VOCs and odours, while demand-controlled ventilation (DCV) systems adjust airflow based on occupancy to manage CO2 levels and reduce energy use.  UV germicidal irradiation (UVGI) systems can be installed in HVAC units to disinfect air and prevent microbial growth on coils. Regular maintenance ensures optimal HVAC performance, and indoor plants can naturally improve air quality by absorbing pollutants and increasing oxygen levels.

In schools, IAQ challenges include VOCs from classroom materials and cleaning supplies, CO2 from high occupancy, allergens like dust and pet dander, and particulate matter from outdoor air and activities.

·         IAQ solutions for Schools benefit from using high-efficiency filters such as HEPA or MERV 13+ to trap allergens and fine particles. Enhanced ventilation with energy recovery ventilators (ERVs) can increase outdoor air exchange while conserving energy. Selecting low-VOC paints, adhesives, and cleaning products minimizes indoor VOC levels, and portable air purifiers with HEPA and activated carbon filters offer additional air cleaning in classrooms. CO2 monitors ensure adequate ventilation for better cognitive function and health, while rigorous cleaning protocols help control dust, allergens, and microbial contamination.

Healthcare facilities pose IAQ challenges, including pathogens like bacteria and viruses, VOCs from medical equipment and disinfectants, particulate matter, pharmaceuticals and chemicals used in treatments.

• IAQ solutions in environments require solutions, such as HEPA filters in HVAC systems and portable air purifiers to capture fine particles and pathogens. UVGI systems installed in air handling units and patient rooms inactivate airborne microorganisms, reducing infection risks. Negative pressure isolation rooms are critical for containing infectious agents, while high air exchange rates with outdoor air, supported by efficient ERVs, help dilute contaminants. Activated carbon filters can remove VOCs and chemical pollutants, and continuous air quality monitoring detects pollutant levels in real-time, ensuring swift action when needed. Strict cleaning and disinfection protocols further minimize the presence of harmful microorganisms and chemicals.

Air exchange technologies within indoor spaces

A combination of technologies and strategies can effectively condition outside air to improve ventilation and air exchange within indoor spaces. ERVs, DOAS, VAV systems, DCV, desiccant dehumidification, IDEC, filtration, UVGI systems, air curtains, and advanced control systems maintain a healthy and comfortable indoor environment. These technologies balance the need for fresh air with energy efficiency, ensuring optimal IAQ across various climates and building types.

Technology for conditioning air

Conditioning outside air maintains good indoor air quality and provides healthy, comfortable indoor environments. Various advanced technologies and methods are used to manage and condition outdoor air.

Energy Recovery Ventilators (ERVs) and Heat Recovery Ventilators (HRVs) play a crucial role in this process. These systems exchange heat between incoming fresh air and outgoing stale air, reducing energy consumption by preconditioning the incoming air. ERVs, in particular, also transfer moisture, helping to balance humidity levels indoors. These systems contribute to energy savings and improved indoor comfort as they improve humidity.

Dedicated Outdoor Air Systems condition and deliver 100 percent outdoor air to indoor spaces. These systems can dehumidify, heat, or cool the incoming air as required. By separating the functions of ventilation and temperature control, DOAS ensure a consistent supply of fresh air while allowing other HVAC systems to operate efficiently.

Variable Air Volume (VAV) systems modulate the amount of outdoor air supplied to different zones within a building based on real-time demand. By adjusting air volume as needed, VAV systems improve energy efficiency and ensure optimal comfort, delivering the right amount of conditioned air to each space depending on occupancy and air quality requirements.

Demand-controlled ventilation (DCV) systems use sensors to monitor conditions such as CO2 levels, volatile organic compounds (VOCs), and occupancy. These systems adjust ventilation rates, increasing fresh air supply when necessary and reducing it during periods of low occupancy. This adjustment helps to optimise air quality and reduce energy consumption.

Together, these technologies provide effective solutions for conditioning and managing outside air, ensuring healthier, energy-efficient indoor environments customised to specific needs.

Expertise shared by- 

Chirag Kataria 
(IIT Kharagpur)
Independent Consultant
Indoor Air Quality