12/16/2014

How to Manage Indoor Air Pollutants

Indoor air pollutants are often unseen by the human eye but can wreak havoc on a building and home inhabitants. In some cases, inhabitants may experience issues like headaches and allergies. In severe cases, indoor air pollutant health risks may include pneumonia, stroke, cancer, and even death. This is why it’s important to stay informed about the types of indoor air pollutants, as well as some techniques to keep your home’s air fresh and healthy.

Particulate Matter

Indoor air pollutants are placed into two categories: particulate matter and gaseous pollutants. Particulate matter is made of liquid droplets, microscopic solids, or a combination of the two suspended in air. Particulate matter is also known as particle pollution. These pollutants can be found in the home in several forms, such as organic chemicals, soil, metals, and dust particles. Acids may include sulfuric and nitric acids. Biological contaminants are also common types of particulate matter.

Biological contaminants may include:

  • Bacteria
  • Viruses
  • Molds
  • Pollen
  • Animal Dander
  • Droppings from cockroaches and dust mites

Gaseous Pollutants

The other category of indoor air pollutants is gaseous pollutants. These are defined as organic chemicals or compounds and combustion gases which are not attached to solid particles. There are hundreds of types of gaseous pollutants that have been found in indoor environments. Combustion gases may include nitrogen dioxide and carbon monoxide. They may come from sources such as combustion appliances, vehicle exhaust from outdoors or attached garages, and tobacco smoke.

Sources of airborne gaseous organic compounds may include:

  • Tobacco smoke
  • Cleaning chemicals
  • Paints, adhesives, and caulks
  • Caulks and waxes
  • Household cleaners and deodorizers
  • Dyes and solvents
  • Hobby and craft materials
  • Pesticides
  • Outdoor sources
  • The food cooking process
  • Metabolic processes of humans, animals, and plants

Reducing Indoor Air Pollutants

There are two main strategies for reducing indoor air pollutants in homes and buildings: source control and ventilation.  As indicated by the name, source control helps to eliminate an individual source of contamination or to reduce the source’s emissions. When possible, source control is the most effective strategy. Examples of source control include adjusting combustion appliances to reduce emissions, having smokers smoke outdoors instead of indoors, and switching from pressed wood products to wood or alternatives to avoid formaldehyde emissions.

Ventilation (Natural Ventilation Vs. Mechanical Ventilation)

It’s important to remember that the best way to solve existing indoor air quality issues is to identify and get rid of the source of indoor pollutants, mold, bacteria, etc.  Some forms of indoor air pollution are harder to eliminate at the source so dilution is the next best option. This is why fresh ventilation is key for homes and buildings.

General ventilation may occur naturally or mechanically such as through an HRV or ERV system. Natural ventilation occurs through open doors and windows. Infiltration is the process of air flowing into the home through openings, cracks, and joints around the home.  While these can provide a source of ventilation in the home there are drawbacks.  Natural ventilation through cracks, openings, doors, and windows often proves unreliable in the long term. This is because the process depends on several varying factors that work together to dictate efficiency in removing old air and introducing new air. The main shortfalls of natural ventilation involve the driving forces of the process, the difficulty in controlling airflow, and the potentially harmful impact improper ventilation can have on the building’s envelope.

Mechanical ventilation can help overcome the shortfalls that occur from natural ventilation.  A Zehnder HRV or ERV system works to exhaust air from moist rooms like bathrooms and kitchens while introducing a balanced amount of fresh filtered air into habitable spaces like bedrooms and living rooms. With these mechanical ventilation systems, home and building owners have greater control of proper building ventilation, regardless of external factors like the weather or the time of year.