Indoor Air Quality (IAQ) is one of the most important areas of Indoor Environmental Quality (IEQ), particularly, in terms of the impact of a building on the health of occupants. IEQ encompasses more than air quality, including thermal comfort, visual comfort and acoustical quality…
Most people spend as much as 90% of their time indoors. They ingest almost 3-4 liters of water and one kg of food daily, but inhale almost 15 liters of air each day. Therefore, maintaining a superior Indoor Air Quality (IAQ) in occupied spaces can translate to occupant health and safety, greater productivity and reduced healthcare costs.
Indoor air is often more polluted than outdoor air (albeit with different pollutants). Research has shown that indoor air in buildings can be two to five times—and occasionally up to 100 times—more contaminated than outdoor air. In fact, indoor air is often a greater health hazard than the corresponding outdoor setting, although this has not changed the common understanding of air pollution.
Indoor air pollution consistently ranks among the top five environmental risks to public health. US Occupational Safety and Health Administration (OSHA) estimate that 30 percent of workers in non-industrial buildings—including offices, schools and hospitals—are exposed to poor indoor air quality.
The World Health Organization (WHO) estimates that 4.3 million people in 2012 lost their lives due to indoor air pollution. Estimates from the WHO and others suggest that between 30 and 150 times more people are killed due to indoor air pollution than global warming.
Air tight buildings made for higher energy efficiency – if not provided with sufficient ventilation – lead to a common problem viz buildup of carbon dioxide and various pollutants. This leads to “sick building syndrome,” the term introduced in 1980s to describe the increasingly common maladies caused by improperly designed and ventilated buildings. By 1984, a WHO Committee reported that “up to 30% of new and remodeled buildings worldwide may be the subject of excessive complaints related to indoor air quality.” Since that time, consciousness increased on this subject mainly in the developed countries and standards were introduced.
What is indoor air quality?
IAQ is one of the most important areas of Indoor Environmental Quality (IEQ), particularly, in terms of the impact of a building on the health of occupants. IEQ encompasses more than air quality, including thermal comfort, visual comfort and acoustical quality.
Indoor Air Quality (IAQ) deals
with the content of interior air that could affect health and comfort of
building occupants. It refers to the presence or absence of air pollutants in
buildings. There are many different types of pollutants that can affect indoor
air and they come from a wide range of sources.
According to the US
Environmental Protection Agency (EPA) and National Institute of Occupational
Safety and Health (NIOSH), the three key elements that contribute to the
quality of the air people breathe when they are inside include,
• Introduction and distribution of adequate ventilation air
• Control of airborne contaminants
• Maintenance of acceptable temperature and relative humidity
How does Indoor Air Pollution impact us?
Poor IAQ leads to a variety of health risks that have significant costs for the people affected directly as well as for their family members, employers and society at large. Despite the fact that IAQ can have an immense impact on health and general quality of life, it is generally an unregulated field.
The Environmental Protection Agency notes that occupants may experience adverse health effects from indoor air pollutants soon after exposure – or years later. Health conditions associated with poor IAQ can be categorized as either building related illness (BRI) or sick building syndrome (SBS).
Building Related Illness (BRI)
As defined by the World Trade Center Resource Guide, BRI includes specific, identified maladies attributed to an identified material, product or system in a home or building. Examples include Legionnaire’s Disease, hypersensitivity pneumonitis, humidifier fever and asthma-like symptoms in non-asthmatic individuals. Approximately 25% of the ailments associated with indoor air quality can be identified specifically and are attributed to BRI.
Sick Building Syndrome (SBS)
SBS refers to a general set of
symptoms that affect building occupants during the time they spend in the
building and that diminish or go away during periods when they leave the
building. SBS cannot be traced to specific pollutants or sources within the
building, and it typically is multi-factorial, or caused by a number of factors
combined with or worsened by inadequate ventilation. About 75% of
building-related health cases are classified as SBS. Common SBS symptoms
include headaches, nose, eye and throat irritation, a dry cough, dry skin
irritation, dizziness or nausea, difficulty concentrating and fatigue.
SBS and BRI are frequently
confused with each other. BRI usually entails a specific diagnosis of a set of
symptoms caused by a specific environmental factor, one that has developed into
an illness that persists whether that factor is present or not. SBS refers to
more general symptoms of malaise or discomfort, which are temporary and limited
to time spent in the building. Conversely, BRI is often associated with a
longer recovery time than SBS symptoms.
What are indoor air pollutants and where do they come from?
There are many potential sources that lead to poor indoor air pollution with the most common being mold, radon, second hand tobacco smoke, smoke from burning wood, gas furnaces and various allergens.Volatile Organic Compounds (VOCs), formaldehyde, pesticides, lead and asbestos are also common sources of air pollution. Some of these items are naturally occurring, some are man-made and some depend on chemical reactions to occur under the right conditions.
Particulate matter is the prime
villain. The most lethal are the smallest particles (also known as PM2.5, for
particulate matter smaller than 2.5 microns in diameter, about one-third the
diameter of a red blood cell), which are produced by combustion and household
activities like cooking. These specks can get deep into the lungs, tarring the
airways and weathering the heart, disrupting its ability to breath properly.
Many studies have linked exposure to PM2.5 with heart attacks, cardiac
arrhythmias, strokes, chronic obstructive pulmonary disease, worsened symptoms
of asthma and an increased risk of respiratory illness.
Worldwide, particulate matter
contributes to about 800,000 premature deaths each year, according to the
WHO, making it the 13th leading cause of death worldwide. Other pollutants also
cause major problems, especially indoors—radon, a gas produced naturally in the
Earth, is the second leading cause of lung cancer in the US, and
additional gases like carbon monoxide and volatile organic compounds (VOCs)
cause innumerable health effects.
Strategies to control indoor air pollution
Even though the factors that affect quality of indoor environment are numerous, the good news is that most indoor environmental problems can be prevented or corrected. Achieving better IAQ in buildings requires proper application of science and technology. It calls for an optimum combination of proper buildings materials, effective ventilation systems design and indoor pollutant control mechanism. Some broad guidelines for better IAQ are briefly described below:
Materials Selection
Selection and use of low-emitting, non-toxic materials to construct and furnish the buildings is one of the key elements to meet a goal for good air quality. The evaluation process for materials calls for understanding the emission potential of each product under consideration. Several categories are considered in a standard testing procedure, including amount of particulates, total volatile organic compounds (TVOCs), and formaldehydes. Materials and products that are third-party certified for conformance with accepted IAQ standards are most recommended. Examples of IAQ Third-party Certification Programs include certified laboratories.
Ventilation Systems
Ventilation involves introducing exterior air into an interior space while exhausting stale interior air to the outside. A variety of common strategies and technologies can be used, including operable windows and exhaust fans. Mechanical systems with adequate ventilation rates, appropriate pressures, and efficient air-filtration are some of the effective strategies for better IAQ.
During Construction
The indoor air in buildings and homes can be compromised by construction activities even before occupants move into a space. In both residential and commercial sustainable projects, a “Construction IAQ Management Plan” should be prepared by the contractor and approved by the client or designer prior to commencement of the work. IAQ strategies should then be implemented during interior construction works to avoid health issues for workers (during construction phase) and occupants (during occupancy phase).
During Operations
Both workers and management can take steps to help maintain good indoor air quality. For employees, EPA recommends the following:
• Refrain from blocking air vents, as doing so can unbalance your office’s HVAC system and affect the ventilation of neighboring offices.
• Comply with your building’s smoking policy and smoke only in designated areas.
• Clean up spills immediately and report any water leaks to management to avoid the possibility of mold growth.
• Dispose of all garbage promptly in the proper receptacle.
• Store food properly. Do not leave food in your desks or on shelves.
• Contact building management if you suspect an IAQ problem.
EPAs tips for employers include
• Maintain a good working relationship with building management regarding IAQ issues.
• Regularly check your building’s HVAC system to ensure it’s in good working order, and coordinate with building management “when responsibility for design, operation and maintenance of the ventilation system is shared,” EPA states.
• Create a policy that protects non-smokers from secondhand smoke exposure.
• Refrain from using products that can cause IAQ problems.
• Use pest control products only when necessary, and non-chemical methods if possible.
While above strategies can be a good start, there can be several other more elaborated strategies applicable to different type of buildings or applications. As per our experience at AEON on such IAQ projects, it is experienced that a thoughtful and an integrated design approach is required to be applied in a building design and validated through computer simulation techniques to achieve enhanced IAQ.
Indoor air quality crosses economic status, race and ethnicity. Poor indoor air quality can be present at work, home, school or vehicles. Hence, this is a subject that needs to be addressed carefully for our present as well as future well-being.
AUTHORS CREDIT & PHOTOGRAPH
Ashish K Jain
Director,
AEON Integrated
Building Design
Consultants LLP,
New Delhi
