Indoor Air Quality Testing 

Quality air is required at homes and workplaces as living in a healthy and clean environment improves an individual’s health, comfort, and performance. One cannot control the outdoor air quality, but one can ensure better health by improving indoor air quality. And it begins with identifying levels of indoor contaminants and finding ways to restore good air.

Indoor Air Quality (IAQ)

Indoor air quality denotes air quality within or around the buildings and homes regarding its humidity, temperature, and air constituents. 

According to World Health Organization (WHO), 9 out of 10 people regularly breathe polluted air. Not just outdoor air exposes humans to pollutants; sometimes, the air inside the home can be far more polluted than outside the home. However, the focus is on outdoor air pollution, giving prevalent IAQ issues less attention; hence, most people are unaware of it. Various research shows that the urban population spends more than 90% of their time indoors, i.e., in homes, offices, educational institutes, and other commercial and industrial buildings. It includes vulnerable groups of the population in daycare centers and retirement homes. Therefore, to ensure people’s health, quality checking of indoor air is highly needed in the current situation. Maintaining good IAQ has become challenging for both low or middle and high-income countries.

Sources and Compositions of Indoor Air pollutants

Various activities generate indoor air pollutants and penetration of outdoor air pollution. Emissions of gases from building products and materials used, biofuel, cooking gases, gas heaters, fireplaces, tobacco and smoking, and animal hairs contribute to indoor air pollution. Pollutants get trapped in carpets or flow with indoor air, which cannot exist due to inadequate ventilation.

The exact amount of air pollution in each indoor area varies. It can change by state, county, or even by town. Similarly, it varies with the nature of buildings, whether homes, offices or industries. More impurities, gases, and particulate matter are found in parking areas and garages compared to houses.

Common indoor pollutants are categorized as,

  • Toxic compounds
  • Infectious elements
  • Allergens
  • Microbes
  • Safety gases

Serious health problems causing particles are radon, carbon monoxide, mold, harmful chemicals, dust (Respirable suspended particulate matter RSPM – PM10 and PM2.5), volatile organic compounds (VOC), ozone, and microbes. VOC are carbon-containing substances including hydrocarbons, alcohols, aldehydes, and organic acids are formed by building materials such as furniture, plastics, carpets, wallpapers, cleaning materials, copy machines, lacquers, solvents, synthetic fragrances, insecticides, and tobacco smoke. 

Impacts of Indoor Air Pollutants On Health

The air with poor quality can contribute to serious health problems. Yearly, many people die due to related issues. Some of the harmful impacts on the health of breathing polluted air are:

  • respiratory infections
  • congestion
  • sneezing
  • coughing
  • asthma 
  • fatigue
  • eyes, nose, or throat irritation
  • headaches
  • dizziness
  • pneumonitis
  • humidifier fever

IAQ Monitoring Parameters:

The indoor air quality monitoring parameters are of two types; comfort and contaminants.

Comfort parameters contain relative airflow, humidity, and temperature. These parameters have a direct connection to the comfort of a human being.

Contaminant parameters are the impurities found in the air. And the air quality is measured by the air quality index. 

IAQ Testing

Before proceeding with the indoor air quality monitoring procedure following things should be kept in mind:

  • Building type, whether it is residential, commercial, or sensitive building
  • Building ventilation characteristics
  • Variety of pollutants to be monitored
  • Number of people
  • Activities like burning, smoking
  • Outdoor pollution
  • Disease history of people living in that place

It is also essential to know the monitoring schedule, equipment specifications, sampling point selection, etc.

Testing Method

To check the types and levels of pollutants present in the air at home or offices, the various company offer indoor air quality testing or inspecting services or indoor air quality surveys. It is carried out using indoor air quality equipment for different harmful parameters. Regular calibration per pollution control board standards is a must in the equipment used in indoor air monitoring and testing. 

By evaluating health symptoms, indoor air quality can be identified as well. It may also provide clues about the source of the pollution. For example, nausea and confusion track more closely to symptoms of dangerous levels of carbon monoxide in the home. A scratchy throat or watery eye can be an allergic reaction to potential pollutants.

Testing Duration and Time

Two hours of indoor air quality monitoring, one hour each in the morning and the evening, is generally recommended, as it is the best practice. But, 24 hours /full-day monitoring can be a better option if particular contaminants need to monitor.

The duration of monitoring can vary from 15 minutes to several days, depending on the type of data or sample required. The longer survey obtains a more accurate result.

The first three samples are taken mainly at the monitoring site; additional samples or points are monitored when these ranges exceed 5-15%.

Steps of test methods for IAQ

Checking air quality with an indoor air quality monitor

An indoor air quality monitor is a simple option for monitoring indoor air quality. It is an always-on electronic device that consistently tests and reports pollution levels inside the home. Almost all of them test for particulate matters, chemical pollutants, and humidity; some provide additional information like outdoor air quality, carbon dioxide, carbon monoxide, and even formaldehyde levels.‍

Many models have a display panel that shows the values and readings in real-time on the device itself or shares specific readings with a cell phone via an application. Most of them can pair with devices like thermostats to help manage indoor air and energy usage; they also have air quality sensors that provide air quality measurements of humidity, VOC, particulate matter level, and air quality index.

Testing for mold in the air

A typical household pollutant in the air just about anywhere the indoor air quality monitor won’t report is mold. Stachybotrys chartarum (black fungus), Penicillium, Aspergillus, Cladosporium, etc., are some harmful molds that grow inside the home . Home mold tests, which are cheap and readily available, are almost entirely useless. A standard home mold test typically has a petri dish that is allowed to sit in the home. Along with a culture media, usually potato dextrose agar, with its lid open. After a specified amount of time, the petri dish is covered with the lid and incubated for a limited time. It is needed to check whether the amount of airborne mold spores found in homes is excessive. It is usually done by comparing the concentration of mold spores floating at home to the attention of mold spores floating outside.‍

Musty smell and symptoms like sneezing, allergic symptoms, such as stuffy head, headaches, scratchy throat, and runny nose may also be a sign of high mold concentration in the home. It may be found during plumbing leaks or water issues in the home or office. Finding the source is essential to fixing the problem.

Installing carbon monoxide alarms

Carbon monoxide is a tasteless, odorless, colorless gas that can build to dangerous levels in poorly ventilated areas. It is fatal if exposed to large amounts of it for too long. It is, therefore, known as a silent killer. According to WHO, carboxyhemoglobin in blood should not exceed 2%.

Carbon monoxide results from fuel combustion, so appliances like gas dryers, gas burning stoves or heaters, gas furnaces, and fireplaces are risk creators. Installing the carbon monoxide alarms is a must to save lives. Because it is dangerous to pets, the elderly, and children, carbon monoxide monitoring is recommended on all levels of the homes.

Many indoor air quality monitors determine CO concentration but don’t typically come with a screaming alarm to save the life from sudden carbon monoxide increase or increase in levels while sleeping; CO alarms are necessary.

Conducting radon test.

Radon, like carbon monoxide, is odorless, colorless, tasteless, and utterly undetectable without a detection device. Although it won’t asphyxiate people, it is dangerous in the long term. Radon is divided by the International Agency for Research on Cancer as a human carcinogen (Group I), most commonly causing lung cancer.

The cracks in the areas around pipes, foundations, floors, or walls can be a source of radon entry. As radon gas forms from the breakdown of natural uranium deposits in the soil, it usually enters the lowest levels of the home and accumulates there.

Solution and Preventive Measures

Indoor air quality monitoring instruments help to understand the range of pollutants, and based on collected data, necessary actions are taken to avoid health issues.

Some of the measures to prevent or fix the problems are:

  • High-efficiency air filtration and air cleaners filter or eradicate all the dangerous airborne contaminants. Air filtration is the first line of defense against indoor pollution. Air purifiers clean the air with two methods. One is to release negatively charged ions, which makes pollutants stick to surrounding surfaces. The other method uses HEPA filters to screen and collect particulates from the air.
  • Most indoor environmental quality problems can be resolved by investigating the source of Carbon monoxide or carbon dioxide and indoor ventilation without measuring specific parameters. Well, ventilation is one of the ways to reduce indoor pollutants.
  • Traditional filters cannot prevent smaller particles like radon. Encapsulation and soil depressurization can be applied to such cases.
  • Dehumidification can reduce the dusty smell and moisture due to mold growth.
  • An air quality professional can be called to solve problems like duct cleaning and installing carbon monoxide detectors.
  • Also, it is essential to maintain the temperature, humidity, and ventilation of a building.


Srijana Khanal

Hello, I am Srijana Khanal. Former faculty teacher in Microbiology Department at National College, NIST. Involved in the field of teaching for almost 10 years. I am very passionate about writing (academic as well as creative). My areas of interest are basic science, immunology, genetics, and research methodology.

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