IAQ looks at the quality of that air indoors such as in a home, school, commercial building etc., and has great importance for public health. It has been found that people spend about 90% of their time indoors that also happens to be having approximately 2 to 5 times more concentration of the pollutants than the air in the outside environment. Sensitive groups like children, older people and people with existing heart or lung diseases are at times subjected to even more pressure. It has also been observed that levels of pollutants in the homes and public places have risen in the past years in part because the newer energy efficient buildings often have little ventilation systems and come with more synthetic household materials and furnishings, cosmetics, chemical pesticides and house-cleaning products.
Common Indoor Air Pollutants
Common Indoor Air Pollutants are substances that lead to degradation of IAQ and health hazards. They come from sources including building materials, cleaning products, combustion devices, biological contaminants such as mold and dust mites, and outdoor pollutants that penetrate houses. Exposure to these pollutants can result in respiratory problems, allergic reactions, and many other health problems. Control measures that work very well include identification of sources of pollutants, enhancing ventilation, and use of air purifiers where necessary.
Most Common Indoor Air Pollutants
Indoor air pollution can come from a myriad number of sources; it may even impact your health. Some of the most common indoor air pollutants are listed below:
- Volatile Organic Compounds (VOCs): These are gas emissions from solid or liquid materials, such as paints, varnishes, cleaning agents, and pesticides. VOCs provoke irritation in the eyes, nose, and throat, pains in the head, and even damage to the liver, kidney, and central nervous system.
- Mold: This is composed of mold spores, which may manifest itself on damp surfaces and produces allergens, irritants, and even toxic chemicals compounds. Inhaling mold can cause people to suffer from respiratory diseases, allergies, and even asthma attacks.
- Carbon Monoxide (CO): As a colourless and odourless gas, this gas is a product of fossil fuels combustion. High levels of CO are said to produce headaches, dizziness, weakness, and even death.
- Particulate Matter (PM): Fine particles, which can be breathed into the lungs and cause respiratory and cardiovascular diseases. Possible sources may be cigarette smoke, cooking, and candles.
- Radon: A radioactive gas that comes into homes through floor and wall cracks. Radon is one of the second biggest causes of lung cancer.
- Asbestos: Fibers, included in older building materials, penetrate the lungs and cause lung disease as well as cancer.
Sources of Indoor Pollutants
Some of the materials used in construction, such as insulation and paints, contain substances like asbestos, formaldehyde, and lead that are hazardous to human health and contribute to indoor air pollution. Besides, some of the household cleaning agents, air fresheners, and insecticides used inside homes contain harmful elements that degrade indoor air quality in a home environment. Combustion devices such as gas stoves, heaters, and fireplaces emit CO, NO₂, and PM as pollutants. Biological indoor pollutants include dust mites, pet dander, mold, and bacteria. Additionally, pesticides and radon, which are outdoor pollutants, get indoors with very little dilution.
Causes of Indoor Air Pollution
Inadequate Ventilation
When the outdoor air supply is insufficient, indoor pollutant levels can rise high enough to constitute health and comfort risks. Buildings are designed and constructed to be tight so that minimal quantities of outdoor air infiltrate; unless supplemented by special mechanical ventilation systems, such buildings tend to contain higher indoor pollutant concentrations.
Effect of Outdoor Air
Outdoor air can enter and leave a building through infiltration, natural ventilation, or mechanical ventilation. Infiltration occurs when outdoor air flows into a building through openings, joints, and cracks in walls, floors, ceilings, and around windows and doors. Natural ventilation involves air movement through open windows and doors, driven by temperature differences between indoor and outdoor air, or by wind. Mechanical ventilation systems range from simple exhaust fans that intermittently vent air from specific spaces, like bathrooms or kitchens, to sophisticated air-handling systems that use fans and ductwork to continuously replace indoor air with filtered and conditioned outside air. The rate at which the outdoors air replaces indoor air is referred to as the air exchange rate. When infiltration, natural ventilation, or mechanical ventilation is limited, the rate of air exchange is reduced, and indoor pollutants accumulate to higher concentrations.
Health Effects of Poor Indoor Air Quality
Poor Indoor Air Quality (IAQ) contributes to a significant health impact since people spend much time indoors. Some of the common sources of IAQ pollutants come from VOCs, particulate matter, carbon monoxide, and other biological contaminants like molds and bacteria. These come from a variety of sources: materials in the building, products used in the home, and combustion.
Some health effects from pollution exposure are immediate, such as irritation of the eyes, nose and throat, headaches, dizziness, and fatigue. These are usually temporary and can be relieved by removing the source of pollution. Indoor pollutants can also trigger or worsen respiratory conditions like asthma.
The risk of immediate reactions varies based on age, health, and sensitivity, which differs from person to person. Reactions to pollutants can sometimes resemble cold or viral symptoms, making it hard to identify the cause. Monitoring when and where symptoms occur can help pinpoint pollution sources, especially if symptoms improve when away from the area. Poor ventilation or indoor climate conditions may worsen these effects.
Health effects, such as respiratory problems and cardiovascular diseases, as well as cancer, could happen years after exposure or after lengthy exposure to environmental contaminants. It may even prove lethal, so indoor air must be improved, even if there are no symptoms or signs.
Indoor pollutants have the potential to cause harm, but definite thresholds or durations of exposure for inducing specific health problems are unknown, and responses vary among individuals. Further research will be required to understand routine as well as peak exposures.
Climate Change and IAQ
Climate change can worsen many pre-existing air quality problems and introduce new ones. People spend about 90% of their time indoors, factors that include outdoor air
quality, indoor activities, and the design, construction, and maintenance of buildings can influence indoor air quality – and thus overall health.
Climate change impacts indoor air in several ways. For instance, deterioration in outdoor air quality due to climate change makes it intrude into the indoor environment. Climatic factors such as higher CO2 levels and increased temperatures increase airborne allergens outside, which find their way inside. Warmer temperatures and new weather conditions lead to the occurrence of more frequent and intense wildfires and smoke and particle pollution even reaching into the indoor environments, thereby increasing the levels of particulate matter indoors.
Furthermore, increased recurrence and duration of heat waves can result in higher indoor temperatures. Climate change is also correlated with an increase in extreme climatic events, such as torrential rains, flooding, and storms, which might damage the building and allow moisture penetration. The eventual indoor dampness and humidity increase could facilitate the growth of mold, dust mites, bacteria, and a variety of biological contaminants. Second, extreme climatic conditions may amplify pest and pathogenic organisms’ indoor transfers.
This can eventually lead to more frequent disruptions of electrical service, making it even harder to maintain good indoor climates and air quality. This situation could also increase the use of portable generators, which can cause carbon monoxide poisoning if used improperly, killing hundreds and injuring thousands every year.
Indoor Air Quality Standards and Guidelines
IAQ means ensuring the air inside buildings is safe and comfortable for people. Poor IAQ will lead to many conditions including respiratory, allergy problems, and long-term illnesses. It is essential to enhance IAQ given the amount of time spent indoors. These considerations will include homes, offices, schools, and healthcare facilities. Some organizations have placed standards and guidelines in a quest to improve the indoor quality of air. The Key Standards and Guidelines for IAQ are mentioned below.
EPA Guidelines
The Environmental Protection Agency is one of the U.S. federal government agencies whose main objective is to protect human health and the environment through the development and application of various regulatory provisions. It says that in terms of dealing with indoor air pollutants, one should control three major elements, such as source control, ventilation, and filtration. Their suggestions have ways in which one can decrease indoor concentration for certain pollutants. These include reducing or avoiding the use of certain chemicals, proper ventilation to bring fresher air outside, and using air filtration techniques that capture contaminants. This emphasis spreads to other types of indoor environments, such as homes and schools.
OSHA Recommendations
The Occupational Safety and Health Administration is the federal agency under the United States government. The agency ensures safe and healthy working conditions through its activities such as standards, enforcement, training, education, and the provision of support and resources to business organizations.
OSHA suggests that the workplace maintains good air quality. In other words, OSHA recommends adequate ventilation and reduce exposure to hazards such as mold dust and chemicals, which is usually accumulated by poorly ventilated areas. Their guidelines shall be particularly very useful in industrial setups where hazardous materials may be present and proper air quality is a critical determinant of workers’ health and safety.
WHO Guidelines
Founded in 1948 as part of the United Nations system, the WHO is a specialized agency focused on global public health. Its key goal is to promote health, keep the world safe, and serve the vulnerable. It works on every level to improve people’s lives all over the world-through education to expanding quality essential healthcare.
WHO has guidelines, and these guidelines are particularly focused on key indoor air pollutants-for example, Particulate Matter (PM), Volatile Organic Compounds (VOCs), carbon monoxide, formaldehyde, and many others. These guidelines aim at reducing the risks posed by indoor pollution to protect vulnerable population groups like children, the elderly, and those still suffering from previous illnesses. WHO aims at increasing their efforts by focusing on long-term health effects and prevention of chronic illness through reduction in poor IAQ.
ASHRAE Standards
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is one of the leading technical authorities on IAQ, particularly in the building design and operation field. ASHRAE establishes standards, for instance, Standard 62.1 deals with commercial buildings while the residential counterpart is Standard 62.2 dealing with ventilation rates, air quality control, and moisture control. These standards are widely used to engineer and architecture for the proper design and maintenance of HVACs into supporting good indoor air quality. In addition, their guidelines give advice on how to mitigate specific contaminants, air exchange rates management, and the application of the advance method in air purification.
A package of strategies to improve indoor air quality usually includes source control, which aims at identification and reduction or even elimination of pollutants, such as smoke, chemicals, and allergens; adequate ventilation, which provides sufficient outdoor air to dilute indoor pollutants through natural or mechanical means; and air cleaning, which uses air purifiers or filtration systems to capture harmful particles like dust, pollen, and microbial contaminants. These approaches work in tandem to ensure that there is a healthier indoor environment that shields the occupants from short-term and long-term health problems caused by poor-quality indoor air.
Sustainable Building Practices for Healthier Indoor Environments
Manage the Design and Construction Process
Such basic decisions as site selection, building orientation, outdoor air intakes, and heating, cooling, and ventilation systems are critical to good IAQ. Problems in many indoor air quality cases arise from the fact that IAQ considerations are neglected at the design initiation stage. Failure to focus on IAQ from an early stage can have serious consequences in terms of air quality and lost opportunities to improve indoor environmental conditions.
Indeed, unless installation is also good, even a sound design can be severely compromised by poor installation. For that reason, a high-level commitment to full commissioning is critical. This needs to start early in the design phase and extend into occupancy, commissioning systems and assemblies most important to good IAQ.
Improved Ventilation Systems
Heat recovery ventilation and energy recovery ventilation provide energy-efficient mechanical ventilation with continuous fresh air, filtering pollutants, and maintaining energy efficiency. They are, in fact, essential for modern airtight buildings – where natural airflow is limited, helping to maintain indoor air quality without losing more energy than is necessary.
HRV systems involve the transference of heat through a heat exchanger from incoming fresh air to outgoing stale air, recovering a good amount of the energy used in either heating or cooling. Thus, it offers easy circulation of fresh air with minimal energy wastage, making it highly efficient in terms of maintaining comfortable temperatures indoors.
ERV systems transfer heat but also swap moisture between the air streams, thus helping to maintain humidity levels inside and prevent dry air in winter or too much moisture in summer, factors that can depress comfort and compromise air quality. They are especially useful in climates with extremes of humidity.
HRV and ERV systems also improve indoor air quality by continuously removing pollutants, allergens, and excess moisture from indoor spaces, with less energy consumption. They promote healthier and more comfortable indoor environments through controlled ventilation and optimization of energy use.
Reduce Contaminant Concentrations
Proper removal of pollutants and contaminants from indoor environments can be said to aid in maintaining quality indoor air and in safeguarding the health of occupants in buildings. This can be attained using ventilation, filtration, and air-cleaning methods. Ventilation means reconstruction of outdoor air into the house, either naturally, by opening windows and through curtains, or mechanically, using fans and ducts, to depress harmful sourced pollutants such as VOCs (volatile organic compounds), CO2 (carbon dioxide), and particulate matter. Therefore, ‘filtering-the-air’ means applying High-Efficiency Particulate Air (HEPA) filters that eliminate airborne dust, pollen, and other particles. These filtration devices must be maintained regularly to operate efficiently. Moreover, air-cleaning devices, like UV and ionizers, can prevent molds and aerosolized contaminants from being present in the air in the first instance. UV systems achieve this goal by decimating the very microorganisms that wish to plague the air; ionizers bundle dust together so that they are heavy enough to fall. Hence, providing complete ventilation and filtration, and ideally integrating different options into one system can help improve IAQ for human health, comfort, and productivity. Indeed, continued maintenance and operations should focus on monitoring and maintaining these systems for effective reductions of airborne contaminants.
Efficient Filtration System
High efficiency and advanced filtration systems HVAC are significant and play a crucial role in indoor temperature control and indoor air quality management while saving energy. Such systems are designed to work more efficiently than regular models as they work at various speeds, utilize variable-speed motors, and the smart thermostats optimize energy use directly.
They have high-grade filters, like HEPA or MERV, which can catch finer particles in the air, such as dust, pollen, and mold spores. Other systems have an added activated carbon filter that removes odours and harmful gases. They also address indoor humidity, thereby preventing molds from occurring and providing a room with better comfort. Regular maintenance, such as cleaning or replacing filters and inspecting ductwork, is essential to prevent dust and mold buildup, thereby ensuring continued efficiency and air quality. Overall, these advanced HVAC systems contribute to healthier indoor environments and promote sustainable energy use.
Moisture Control and Insulation
Sustainable buildings usually utilize moisture-resistant materials and clever design techniques to effectively prevent conditions leading to dampness, mold growth, and humidity-related health issues. They use treated wood, vapour barriers, and moisture-resistant drywall purposes that do not allow water to collect in them or cause them to deteriorate. The design techniques also include sloping roofs, good drainage systems, and ventilation in appropriate places, which further reduce the accumulation of moisture in vulnerable areas.
Proper insulation in such buildings regulates the indoor temperature and reduces energy consumption. Above all, it involves good quality insulation materials like cellulose, spray foam or rigid foam, which improve thermal performances, though minimizes the risk of condensation, as it ensures inner ambient temperatures. This should lead to a comfortable living environment, thus increasing well-being among occupants while lowering energy consumption and costs. Together, these will add up to a healthier and more energy-efficient indoor environment more consistent with sustainable building practices.
Limiting Entry of Outdoor Contaminants
Poor outdoor air quality poses quite a number of challenges. Historically, IAQ enhancement is done by airing with outdoor air, assuming the latter to be cleaner than the former. Unfortunately, it is generally not so because outdoor air may have more contaminants in its ranks; if they are not sufficiently treated, it becomes more hazardous to IAQ. Outdoor pollutant levels may be elevated at a regional level or due to more local sources such as motor vehicle exhaust and activities in adjacent buildings. While a few green building programs promote higher ventilation rates, strategies that increase rates of outside air can be counterproductive to good indoor air quality unless enhanced with effective filtration and air cleaning.
The Future of Indoor Air Quality: Innovations and Technologies
New technologies are creating an indoor air-quality scenario that is both healthier and more efficient. Recent examples in this direction include common smart air quality monitors fitted with sensors that can detect a variety of pollutants, such as VOCs, particulate matter, and carbon dioxide. They can be programmed to turn on HVAC without requiring any external intervention or to alert the user if air quality reaches its limits. Other advanced filtration technologies, including UV-C light and nanotechnology filters, are changing the face of pollutant capture and neutralization of airborne pathogens.
Artificial intelligence is optimizing IAQ through the analysis of sensor data to determine adjustment to ventilation and predict pollution patterns, thereby increasing energy efficiency and air quality. Biophilic design – which includes the introduction of plants inside buildings – has been increasingly used for their natural air purifying effects.
The future will concentrate more on giving people a smarter, sustainable way of keeping indoor air safe and comfortable, as green building standards like LEED continue the surge in attention towards indoor air quality.
Dipanwita Samaddar, a Subject Matter Expert (HVAC), is connected to Zuru Tech India Pvt. Ltd.
