The growing use of air conditioning (AC) worldwide is leading to conditions that are more favorable for increased person-to-person transmission of airborne infections such as tuberculosis (TB), influenza (flu), and measles. The impact of AC on airborne infection and indoor air quality is almost immediate, unlike the delayed environmental effects of increased CO2 emissions. This is because in order to use an air conditioner effectively, windows and doors must be closed, which eliminates natural ventilation that is relied upon by a large portion of the world to clean and purify indoor air. Additionally, the most popular and effective AC types are split or ductless ones, which cool and dehumidify room air without supplying outdoor air exchange. Air purification with UVC lamps becomes essential to remove contaminants from the air in a room.

Upsurge in TB cases

Reports from Mumbai indicate an increase in drug-sensitive TB cases among children. Data released by the BMC in 2022 showed that pediatric TB cases have been increasing every year, accounting for 7% of the total cases in 2019 and 9% in 2021. In a city where up to 60,000 new TB patients are registered every year, health activists point out that pediatric TB care is highly inadequate.

TB is a highly infectious disease with a high global mortality rate caused by the bacteria Mycobacterium Tuberculosis. TB spreads most commonly through droplets breathed or coughed into the air. Even if they show no symptoms of TB, children may still be infected with the germs. Controlling TB infection and maintaining indoor air quality is a top public health priority.

Stages of TB

Exposure. When a child comes into contact with someone who is a carrier of the TB pathogen, this may happen. The child will show no symptoms, a normal chest X-ray, and a negative skin test.

Latent Tuberculosis. This occurs when a child carries TB germs in the body but shows no symptoms. The child’s immune system makes the TB bacteria dormant. The skin test for this child would be positive, but the chest X-ray would be normal. He or she is not able to infect others.

TB illness. This occurs when a child shows signs of an ongoing infection: both a positive chest X-ray and a positive skin test would be present for this child. If left untreated, he or she may transmit the illness.

Control of Indoor Air Quality and Tuberculosis Transmission

For a healthy human life, living in a healthy environment is a must. Indoor air frequently contains bacteria and viruses that could be dangerous to one’s health, especially for those with weakened immune systems. When a child with tuberculosis coughs or sneezes, the germs are released into the air as an aerosol, spreading the disease. In recent years, schools and medical clinics have reported outbreaks of tuberculosis, along with homeless shelters, jails, call centers, and banks, which are places with large numbers of people and poor ventilation.
Indoor air quality can be regulated in three ways to lower the risk of TB and other disease transmissions: dilution, filtration, and air purification by UVC lamps. These treatments not only effectively treat Tuberculosis but also other microbial diseases including influenza.

1. Dilution lowers the concentration of infectious organisms in a place by introducing more outside air into the area. Dilution spreads the germs over a broader volume of air, reducing the likelihood of spreading without killing the bacteria.
2. Filtration decreases the concentration of infectious agents in an area by passing the air through a high-efficiency particulate air (HEPA) filter that traps bacteria and viruses (as well as other particles). The extra fan power needed to get air through the filter with HEPA filtering can result in higher running costs.

3. Purifying the air with UVC lamps removes infectious pathogens in the air as ultraviolet (UV) radiation damages the DNA of bacteria and viruses, including those of Mycobacterium Tuberculosis. The infectious pathogen can no longer replicate due to this DNA damage. However, UVGI air purification requires protecting people in the treated area from excessive UV radiation exposure. Therefore, certain safeguards are necessary. UVGI technology has long been used in hospitals and labs for air purification, but it can also be used in public areas where people gather.

These three strategies can be used individually or together.