The Indoor Air Quality (IAQ) did not catch much attention relatively in the past when the buildings were ventilated through natural ventilation. However, to conserve energy in 60s and 70s buildings were designed to be sealed tight. This caused the pollutants released by the construction material or any entrapped outdoor pollutant to build up indoors. The lack of ventilation and indoor air pollutant buildup can cause different adverse health effects among occupants. Maintaining IAQ is critical to our health since we spend majority of our time indoors, whether at home, in an office, or a vehicle. Some of the most common pollutants and their sources indoors are as follows.
| Pollutant | Major emission sources |
| Allergens | House dust, domestic animals, insects |
| Asbestos | Fire retardant materials, insulation |
| Carbon dioxide | Metabolic activity, combustion activities, motor vehicles in garages |
| Carbon monoxide | Fuel burning, boilers, stoves, gas or kerosene heaters, tobacco smoke |
| Formaldehyde | Particleboard, insulation, furnishings |
| Micro-organisms | People, animals, plants, air conditioning systems |
| Nitrogen dioxide | Outdoor air, fuel burning, motor vehicles in garages |
| Organic substances | Adhesives, solvents, building materials, volatilisation, combustion, paints, tobacco smoke |
| Ozone | Photochemical reactions |
| Particles | Re-suspension, tobacco smoke, combustion products |
| Polycyclic aromatic hydrocarbons | Fuel combustion, tobacco smoke |
| Ozone | Photochemical reactions |
| Pollens | Outdoor air, trees, grass, weeds, plants |
| Radon | Soil, building construction materials (concrete, stone) |
| Fungal spores | Soil, plants, food stuffs, internal surfaces |
| Sulphur dioxide | Outdoor air, fuel combustion |
Source: A. P. Jones. (1999). Indoor Air Quality and Health. Atmospheric Environment, 33: 4535-4564.
OHCOW Resource
Air Assess App
Assesses the air quality in your workplace and get options for taking action on any air quality issues
Thermal Comfort
Beside the chemical and biological pollutants, temperature and humidity are key factors which can affect the thermal comfort of an occupant. The thermal comfort can in turn effect the productivity of an occupant. Maintaining temperature and humidity within an optimal range according to the guidelines is also important to avoid any microbial growth indoors.
How it can affect your health
OHCOW has experienced in its numerous IAQ studies at variety of different workplaces (Indoors) that a poor indoor air quality can be associated with headaches, fatigue, respiratory issues like asthma and allergies and respiratory, eye, and nasal irritation, dry skin and eyes etc. by the office occupants.
Investigating IAQ complaints
To investigate adverse health complaints an Occupational hygienist usually measures IAQ parameters such as temperature, relative humidity, carbon dioxide, carbon monoxide, TVOCs, particulate matter with a size fraction of 2.5 micron or sub-micron level, mould spores (viable or non-viable). However, in most cases it is difficult to link one parameter to a particular adverse health effect unless it is obvious. However, bringing the IAQ parameters within the recommended guidelines such as ASHRAE and Health Canada IAQ guidelines resolves the health complaints.
Collecting or summarizing occupants’ health effects complaints is important from strategizing the IAQ parameter sampling standpoint. An occupational hygienist can gather an office occupants’ health effects from the JHSC or the staff during a walk-through survey or by administering a health survey in case of large number of people.
Sick Building Syndrome
In some cases, building occupants complaint of unrelated different bunch of symptoms which do not point towards a particular IAQ parameter. This situation is called Sick Building Syndrome (SBS) and the symptoms can range from vague to subjective health complaints. However, some cases of SBS some occupants can provide valuable information regarding causality.
What about regulations?
Unfortunately. there are no regulations specific to IAQ, however, this is an employer’s responsibility to provide healthy and safe workplace to its employees under general duty clause, section 25(2)(h) of the Occupational Health and Safety Act which states that an employer has to take every precaution reasonable in the circumstances for the protection of workers.
OHCOW Resource
VIDEO: A Brief Overview of Indoor Air Quality Challenges
OHCOW Occupational Hygienists James Miuccio and Sonya Lal give a presentation on how indoor air is affected by pollutants and thermal conditions.
Why Indoor Air Quality Matters
The air we breathe indoors has a direct impact on our health, comfort, and productivity. Since most people spend up to 90% of their time inside homes, offices, and other buildings, maintaining clean and healthy air is essential. Poor indoor air quality can contribute to headaches, fatigue, respiratory issues, and long-term health concerns.
Common Sources of Indoor Air Pollution
Indoor air can be affected by a variety of factors, including:
- Dust and allergens from carpets, furniture, and pets
- Chemicals and volatile organic compounds (VOCs) from cleaning products, paints, and furnishings
- Mold and moisture from leaks or poor ventilation
- Combustion by-products from stoves, fireplaces, or tobacco smoke
- Outdoor pollutants that enter through windows, doors, or ventilation systems
Indoor Air Quality and Contaminants
COVID made the issue of indoor air quality more immediate and crucial in countries all over the world. One of the positive things to emerge from the crisis was that more attention has since been given to the problem of human health and air quality, and the presence of germs and other contaminants in the air we breathe. Following are some videos dealing with indoor ventilation in public and private working spaces.
WEBINAR
Occ-COVID Conversations: Let’s hear from the Engineers & stop the spread!
December 9, 2022 Speakers: Joey Fox, P. Eng, MASc, HVAC Engineer; Marianne Levitsky, MES, CIH, ROH, FAIHA, Occupational Hygienist; Stéphane Bilodeau, P.Eng., Ph.D., Fellow of Engineers Canada, Bioengineering Lecturer at McGill University, CTO at Smart Phases
WEBINAR
Clean Air Really Matters!
Friday, September 16, 2022 – An in-depth presentation on key COVID prevention strategies by a subject matter expert, along with professional framing and discussion with an OHCOW host – and lots of questions (and answers) from our audience. Kevin Hedges, Occupational Hygienist, PH.D., CIH,COH; Joey Fox, P.Eng., MASc.
WEBINAR
Occ-covid Clean Air Playlist
From 2022: See a list of webinars on classroom ventilation, older buildings, risk assessment and more! A concise compilation of COVID era concerns about indoor air assessment that is still valid today.
WEBINAR
Collaborating on Solutions for Cleaner School Air
2024 Occ-Covid Series: What happens in schools affects millions of children and their families, and can drive illness and infection rates in society at large.
Key Factors Affecting IAQ
- Chemical pollutants: Volatile organic compounds (VOCs) from paints, cleaning products, or office equipment; carbon monoxide; radon; formaldehyde.
- Biological contaminants: Mold, bacteria, pollen, dust mites, and viruses.
- Particulate matter: Dust, smoke, and fine particles from combustion sources.
- Ventilation: The rate of outdoor air exchange and the effectiveness of HVAC systems in diluting and removing contaminants.
- Humidity and temperature: Both influence comfort and microbial growth.
Why IAQ Matters
- Health: Poor IAQ is linked to asthma, allergies, and other respiratory conditions.
- Productivity: Workers in environments with good IAQ report higher concentration and fewer sick days.
- Regulatory compliance: Occupational health standards often require monitoring and managing IAQ to protect workers.
Common IAQ Assessment Methods
- Air sampling: Measuring concentrations of specific contaminants (e.g., VOCs, CO₂, PM2.5).
- Ventilation assessment: Checking airflow rates and distribution.
- Building inspections: Identifying sources of moisture, mold, or chemical emissions.
- Occupant surveys: Gathering feedback on comfort and symptoms.
IAQ is essentially about balancing contaminant control, ventilation, and comfort to ensure a safe and healthy indoor environment. Since you specialize in occupational hygiene, IAQ assessments often overlap with exposure evaluations—integrating personal sampling data with building system performance to provide defensible recommendations.
