Indoor Air Quality: A Growing Concern
January 29, 2020Since the passing of the Clean Air Act in 1970 the EPA has extensively studied outdoor air quality. From this we know that exposure to outdoor air pollution is linked to a variety of negative health effects. More recently, a small but growing body of work is examining indoor air quality – which makes sense when you consider that Americans spend almost 90% of their time indoors. While research is still ongoing, there is mounting evidence that suggests that we should design our buildings to ensure that we have healthy indoor air. This means minimizing installing products that emit pollutants as well as installing effective exhaust systems that remove pollutants so that concentration levels do not build. Both of these are particularly important as buildings are designed to be more energy efficient and air tight.
Many products that we put into our buildings contain volatile organic compounds (VOCs). In the short-term, exposure to VOCs can cause irritation to the eyes and respiratory tract, headaches, dizziness and memory loss problems. In the long term, it can cause nausea, fatigue, damage to the liver, kidneys, and central nervous system and cancer. Even the typical levels of VOCs found indoors can have adverse effects. For example, one Harvard study placed individuals in a controlled office environment. They tested cognitive function at conventional VOC levels verses those typical to green buildings where VOC content in products is actively minimized. The study found that in typical green building conditions cognitive function was 61% higher than in the conventional conditions. When they also increased ventilation cognitive function was 101% higher than in the conventional conditions.
Over the past decade VOC content has become more widely reported and green building programs like LEED have normalized a framework for specifying products with reduced levels of VOCs. For projects that are not pursuing a green building certification but are still concerned with indoor air quality, the LEED indoor air quality prerequisites and credits can be used as a reference point. Furthermore, there are a variety of third-party certifications that verify chemical emittance of products. For example, a large array of carpet manufacturers offer products with GREENGUARD certification. A GREENGUARD Gold carpet has been verified as low-emitting. Lastly, the EPA has developed the Indoor airPLUS program which allows builders to demonstrate that they have built a home with healthy indoor air quality without going through a more exhaustive program like LEED.
In addition to VOCs in our homes, we also must consider pollutants from cooking. In homes that use gas appliances we have to be concerned with the open combustion of gas. Additionally, in all homes we have to be concerned with the controlled combustion of the food being cooked. Both of these instances are known to cause high levels of indoor air pollutants, specifically particulate matter (PM). PM is a complex mixture of small particles made up of things like acids, organic chemicals, metals and dust. PM generated from cooking can be dangerous because it is small enough to pass through the nose and throat and lodge in the lungs which over a long period of time can increase the risk for serious health issues.
Pollutants from cooking can be removed from the home through well designed kitchen exhaust systems, though often kitchens are designed to be ventilated through a nearby window. Naturally ventilating the kitchen does not allow the pollutants to be removed as reliably or as rapidly as needed. The best option is to provide a well-designed range hood that covers the entire stove-top and with an air flow rate as recommended by the Home Ventilating Institute. Ideally the fan will operate efficiently and quietly, such as those that are ENERGY STAR certified.
As previously mentioned, programs like LEED are already taking strides to address indoor air quality. In the newer versions of LEED, the credits have become stricter and reflect the more detailed research that is being published. While it seems there is still some time before indoor air quality is regulated in New Jersey code, there is precedent in California which has regulated indoor air quality in various ways through their health and safety codes. Regardless, we will be closely following the emerging research and regulations that are developed throughout the country.