We often take indoor air even though it has pollutants from outside and those released indoors. The Air Quality Index (AQI) measures eight primary air pollutants: particulate matter (PM2.5 and PM10), ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2), lead (Pb), and ammonia (NH3). Accumulation of these and many other indoor pollutants often makes the air in enclosed spaces worse than outdoor air. Dusting and sweeping instead of vacuuming increases particulate matter in indoor air. Carpets, linen, furnishings, and fixtures accumulate dust and allergens. Humidity encourages the formation of mold spores. Smoking, cooking, and heating with polluting fuels, as well as lighting candles and oil lamps, consume oxygen and release pollutants. Numerous commonly used items release toxic chemicals. Inadequate indoor ventilation and inefficient removal of dust, food particles, pet dander, dust mites, allergens, microbes, pests, and pollutants trigger allergy and breathing problems and contribute to respiratory infections, asthma, lung cancer, and other health issues.
VOCs and CECs: The World Health Organization (WHO) considers indoor air pollution “the world’s largest single environmental health risk”. Various indoor activities and substances can contaminate the air, rendering it more hazardous than polluted outdoor air. Volatile organic compounds (VOCs) such as benzene, toluene, xylene, and formaldehyde found in various indoor products and processes, including paints, cleaning products, fuels, and aerosols, readily evaporate at room temperature. They react with nitrogen dioxide and ozone from outside vehicle exhaust to form toxic compounds. VOCs can cause eye, nose, and throat irritation, headaches, and in some cases, damage to the liver, kidneys, or central nervous system. Some VOCs are suspected or proven carcinogens. Contaminants of emerging concern (CECs) are a wide range of chemicals, including some VOCs, pharmaceuticals and personal care products (PPCPs), endocrine-disrupting chemicals (EDCs), microplastics, pesticides, PFAS (per- and polyfluoroalkyl substances), and nanomaterials (in building materials, paints, varnishes, and air fresheners) used indoors that are not yet fully regulated but are causing concern due to potential adverse impacts on our health and the environment.
SWEEPING vs VACUUMING: Vacuuming is more effective at removing fine particles and allergens, while dusting and sweeping is for delicate objects, larger debris like broken glass, and for cleaning areas not reachable with a vacuum cleaner. Sweeping stirs up fine dust, pet dander, dust mites, and allergens and pushes them around instead of picking them up. These airborne particles later settle on all objects in the room. HEPA (High-Efficiency Particulate Air) filter captures 99.97% of airborne particles that are 0.3 microns in size or larger. A vacuum cleaner with a HEPA filter will clean floors, carpets, rugs, furnishings, objects, and the air.
FRESH AIR OR AIR
CONDITIONING: Split ACs and most air conditioners block outside fresh air. They cool and dehumidify stale room air and recirculate it. Since fresh air is required to reduce the concentration of pollutants, odours, and carbon dioxide, air quality is not improved by ACs. In the absence of efficient filtration, cigarette smoke, odours, microbes of airborne illnesses, and allergens from any part of a centrally air-conditioned building get circulated throughout the building. Some models and systems like large HVAC (Heating, Ventilation, and Air Conditioning) systems might have up to 5% fresh air intake. Prolonged air conditioning use can lead to dry skin, eyes, and throat; dehydration; headaches; fatigue and lethargy; increased susceptibility to colds, asthma, allergies, bacterial and fungal respiratory infections; and other health issues. “Air conditioning lung” is characterized by symptoms like a dry cough, wheezing, and chest tightness.
CABIN AIR: Car and bus air conditioning systems usually recirculate inside air to exclude road dust and exhaust fumes. Modern train, aeroplane, and ship air conditioning systems pump in “operation theatre-like” fresh air, replacing air more than 16-18 times per hour. Fresh air intake is compressed when airplanes are at high altitudes. They also use HEPA filters to remove particles, viruses, and bacteria. Submarines and spaceships use systems that remove carbon dioxide and add oxygen to maintain a breathable atmosphere. These facilities include an electrolyser (splits water into hydrogen and oxygen), chemical scrubber (contains soda lime that absorbs carbon dioxide; similar to those used in general anaesthesia), chemical converter (has Potassium superoxide (KO2) that absorbs carbon dioxide and releases oxygen), Sabatier reactor (combines hydrogen from the electrolyser with carbon dioxide to create water and methane, water is reused and the methane is vented out), and pressurized oxygen tanks.
TUNNELS, MINES, WELLS, CAVES, and CAVERNS: These confined spaces have poor air quality due to limited airflow, potential contamination from human activity, droppings of bats and other animals, and the presence of gases like methane released by decomposition of organic matter. Gases can accumulate and become concentrated in confined spaces. Dangerous gases in mines, often called “mine damps,” include toxic, flammable, and suffocating gases like carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), hydrogen sulphide (H2S), and nitrogen oxides (NOx). Gases trapped in rocks (strata gases), toxic gases and dust released by explosives, and exhaust gases of machines and earth movers add to the breathing problems of miners and tunnellers. Radon is a radioactive gas that forms naturally from the decay of uranium in the Earth’s crust and can enter basements and cellars through cracks in foundations and accumulate in sealed homes, and other underground confined spaces posing a health risk and increasing the risk of lung cancer.
MITIGATION AND PREVENTION OF INDOOR AIR POLLUTION: Avoid smoking indoors and burning polluting fuels for cooking and heating. Use a vacuum cleaner with a HEPA filter to effectively capture dust particles, especially on carpets, drapes, and upholstery. Put on an N95 mask and use microfiber cloth or electrostatic dusting tools to capture and trap dust particles on furniture, shelves, and other surfaces. Mop floors to remove stuck dust and dirt. Regular washing and sunning sheets, pillowcases, and blankets eliminate dust mites and allergens. Declutter to reduce dust accumulation. Close windows and doors when the outside air is dusty or polluted. Remove footwear and dirty outerwear before entering indoors. Use doormats at entrances to help trap dirt and dust. Groom pets frequently to reduce pet dander. Use air purifiers with HEPA filters to capture airborne dust particles and improve indoor air quality. Clean or change air filters regularly if using an HVAC system. Instead of harsh chemical cleaners, use natural cleaning products like vinegar, baking soda, and lemon juice. Avoid the use of synthetic scents. Use low-VOC organic pesticides and repellents, cleaning products, air fresheners, aerosols, paints, adhesives, flooring, and other materials. Lead poisoning can be avoided by safely removing peeling paint and avoiding painted toys. Remove old asbestos-containing insulation and deteriorated materials. Block seepage and prevent excessive humidity and mould growth. Spider plants, snake plants, and peace lilies are houseplants that absorb toxins from the air and release oxygen. Other known air-purifying plants include areca palms, broad lady palms, money plants, and Aloe vera. Plant trees around your home and office to reduce dust, pollutants, and heat.
Dr. P.S.Venkatesh Rao is Consultant Endocrine, Breast & Laparoscopic Surgeon, Bengaluru.