Why monitor Indoor Air Quality (IAQ)?

Why monitor Indoor Air Quality (IAQ)?

Article Details

Last Updated

30 March 2024


15 October 2015



What is indoor air quality?

We spend up to 90% of our time indoors, but how often do we think about the quality of the air we’re breathing? Unlike outdoor air, indoor air tends to be continuously recycled, causing it to trap pollutants and allow them to build up within these confined spaces. Indoor air quality (IAQ) broadly refers to the environmental characteristics inside buildings that may affect human health, comfort, or work performance. These IAQ characteristics include the concentrations of pollutants in indoor air, as well as temperature and humidity. Effective measurement of IAQ reduces the health risks associated with poor indoor air, creating a safer, more harmonious environment for people to thrive.

Effective indoor air quality monitoring reduces health risks

Indoor air pollution carries significant short and long-term health risks for inhabitants. Typical symptoms associated with poor indoor air quality include eye, nose, and throat irritation, headache, nausea, dizziness, and fatigue. In some cases, exposure to indoor air pollution can lead to acute and chronic respiratory illnesses, including asthma, lung cancer, pneumonia, systemic hypertension, chronic obstructive pulmonary disease (COPD), Legionnaires’ disease, and humidifier fever. See below for a table of major sources and potential health effects of indoor air pollution.

Poor indoor air quality in the workplace can contribute to decreased productivity, absenteeism, and even possible litigation. By effectively monitoring indoor air quality, employers are able to ensure workers can enjoy healthier spaces with cleaner air, free from potentially harmful chemicals and pollutants. As a result, employers report higher retention levels, increased productivity, and a reduction in absenteeism.

Improve your environment by identifying the sources of poor indoor air quality

Common sources of poor indoor air quality include insufficiently maintained HVAC systems, wood and coal stoves, non-vented gas heaters, environmental tobacco smoke, and vehicle exhaust emissions. When designing or managing a building, it’s important to note things like materials used in construction, carpeting, furniture, and choice of solvents or cleaning supplies. Inadequate ventilation is particularly crucial, as poorly ventilated spaces (along with environmental factors such as temperature and humidity) can amplify the pollutant concentration.

Accurate indoor air quality monitoring alerts residents and building owners to the level and nature of pollution, enabling corrective action. Some of the more typical applications for indoor air quality monitoring include:

  • IAQ complaint investigation and analysis

  • HVAC system performance monitoring

  • Air quality engineering analysis

  • Mould investigation and remediation

  • Health and comfort assessment

  • Airport lounges, shopping malls, offices

  • Schools and kindergartens

  • Hospitals and elderly care facilities

Gas and respirable particulates in the air are the primary sources contributing to poor indoor air quality. See below for a complete list of the most relevant pollutants, along with the sensor type used for monitoring, most common sources of pollution, and the possible health impacts.


Major indoor air pollutants

Major Sources and Potential Health Effects of Indoor Air Pollutants include:

  • Pollutant: Carbon Dioxide

  • Sensor: CO2

  • Major Sources: Sick Building Syndrome (SBS), Excessive Building Occupancy and Inadequate Ventilation

  • Potential Health Effects: Fatigue; Eye, Nose and Throat Irritation; Headaches; Chest Discomfort; Respiratory Tract Symptoms

  • Pollutant: Carbon Monoxide

  • Sensor: CO

  • Major Sources: Non-vented or Malfunctioning Gas Appliances, Wood and Coal Stoves, Tobacco Smoke and Vehicle Exhaust Emissions

  • Potential Health Effects: Headache, Nausea, Angina, Impaired Vision and Mental Functioning, Fatal at High Concentrations

  • Pollutant: Environmental Tobacco Smoke

  • Sensor: COPM

  • Major Sources: Cigarettes, Cigars and Pipes

  • Potential Health Effects: Respiratory Irritation, Bronchitis and Pneumonia in Children; Emphysema, Lung Cancer and Heart Disease

  • Pollutant: Organic Chemicals

  • Sensor: VOC

  • Major Sources: Aerosol Sprays, Solvents, Glues, Cleaning Agents, Pesticides, Paints, Moth Repellents, Air Fresheners, Dry cleaned Clothing and Treated Water

  • Potential Health Effects: Eye, Nose and Throat Irritation; Headaches; Loss of Coordination; Damage to Liver, Kidney and Brain; Various Types of Cancer

  • Pollutant: Ozone

  • Sensor: O3

  • Major Sources: Ground Level Ozone Entering Indoors; Malfunctioning Air Treatment Systems; and Office Photocopiers and Printers

  • Potential Health Effects: Eye, Nose and Throat Irritation; Coughing; Chest Discomfort; Reduced Lung Function; Shortness of Breath

  • Pollutant: Nitrogen Oxides

  • Sensor: NO2

  • Major Sources: Non-vented or Malfunctioning, Gas Appliances and Vehicle Exhaust Emissions

  • Potential Health Effects: Eye, Nose and Throat Irritation; Increased Respiratory Infections in Children

  • Pollutant: TSP (total suspended particulates)PM10 (thoracic fraction ≤10 μm)PM2.5 (respirable fraction ≤2.5 μm)PM1 (particles ≤1.0 μm)

  • Sensor: PM

  • Major Sources: Cigarettes, Wood and Coal Stoves, Fireplaces, Aerosol Sprays and House Dust

  • Potential Health Effects: Eye, Nose and Throat Irritation; Increased Susceptibility to Respiratory Infections and Bronchitis; Lung Cancer

  • Pollutant: Formaldehyde

  • Sensor: CHCO

  • Major Sources: Pressed Wood Products e.g. plywood and MDF; Furnishings; Wallpaper; Durable Press Fabrics

  • Potential Health Effects: Eye, Nose and Throat Irritation; Headache; Allergic Reactions; Cancer

Major Sources and Potential Health Effects of Indoor Air Pollutants include:

  • Pollutant: Biological Agents (Bacteria, Viruses, Fungi, Animal Dander, Dust Mites)

  • Major Sources: House Dust; Pets; Bedding; Poorly Maintained Air Conditioners, Humidifiers and Dehumidifiers; Wet or Moist Structures; Furnishings

  • Potential Health Effects: Allergic Reactions; Asthma; Eye, Nose and Throat Irritation; Humidifier Fever, Influenza and Other Infectious Diseases

  • Pollutant: Asbestos

  • Major Sources: Damaged or Deteriorating Insulation, Fireproofing and Acoustical Materials

  • Potential Health Effects: Asbestosis, Lung Cancer, Mesothelioma and Other Cancers

  • Pollutant: Lead

  • Major Sources: Sanding or Open-Flame Burning of Lead Paint; House Dust

  • Potential Health Effects: Nerve and Brain Damage, Particularly in Children; Anemia; Kidney Damage; Growth Retardation

  • Pollutant: Radon

  • Major Sources: Soil Under Buildings, Some Earth-Derived Construction, Materials and Groundwater

  • Potential Health Effects: Lung cancer

Building a brighter future with international standards

As a result of increased awareness of the risks of poor-quality air indoors, governments around the world have been tightening up standards and requiring building owners to monitor indoor air quality. To this point, increased standards have applied to public places and office buildings, though this could extend to newly built residential buildings in the future.
The trend towards tighter regulation is particularly evident in Asia, where people often spend a large amount of time indoors in air-conditioned environments. In recent years, Singapore, Taiwan, and Hong Kong have all taken steps to better protect human health indoors. In some countries, indoor air quality can be worse than outdoor air quality, especially considering the ratio of time spent indoors versus outdoors.

Recognizing a need to promote healthy indoor air, international green building organizations have developed standards like WELL and LEED. These standards serve as a benchmark for developers and building owners, creating a framework for ensuring healthier outcomes and sustainable designs. There are also several air quality mitigation methods individual citizens and communities can undertake to reduce indoor air pollution and safeguard public health.


Obtaining accurate, credible indoor air quality data

There are two main methods for assessing the quality of indoor air:

  • Real-time (continuous) measurements. Real-time monitors can be used for the detection of pollutant sources, providing information on the variation of pollutant levels throughout the day. Aeroqual is one such manufacturer of equipment for real-time indoor air quality monitoring.

  • Integrated sampling with subsequent laboratory analysis. Integrated samples, normally obtained during the 8 working-hours for offices, can provide information on the total exposure level of a particular pollutant.

Regardless of the method, it is important to ensure the correct operation of the equipment and handling of samples. One must also follow strict quality assurance procedures, including equipment calibrations and operation, per the manufacturer’s instructions.

How Aeroqual can help improve your indoor air

We have a range of indoor products to suit your application, from fixed monitors to portable monitors – including our new Indoor Air Quality Test Kits. View some of our recent indoor air quality case studies for real-life examples of how we’ve helped customers improve their indoor air.

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