Page 84 - Occupational Health & Safety, September 2019

INDOOR AIR QUALITY
Curious and Curiouser
Remarkable indoor air quality case studies and best practices
BY LOUISE VALLEE
The World Health Organization estimates that as many as 30 percent of new or remod- eled office buildings report excessive rates of occupant indoor air quality (IAQ) related health and discomfort complaints. Typical indoor air quality complaints include headache, fatigue, allergy symptoms, mucous membrane irritation, and nau- sea. These symptoms are common among the gen- eral population, contributing to a lack of management support for investigation prioritization.
More serious IAQ health conditions can be poten- tially attributed to mold, bacteria, asbestos, fiberglass, animal urine and feces, and formaldehyde. The ma- jority of IAQ complaints are usually valid and can be resolved through resource commitment to exposure assessment, environmental monitoring, and imple- mentation of corrective measures. The benefits of IAQ problem resolution can range from improved occu- pant safety and health status to, at least, distraction removal, both supporting increased productivity.
Poor IAQ Sources
IAQ contaminants can arise from building interior or exterior sources. Poorly designed, maintained, or operated building ventilations systems may not remove IAQ contaminants and exacerbate health ef- fects and symptoms. Sometimes building occupan- cies change without ventilation upgrades or control measure installation, resulting in IAQ contaminant
generation and spread.
IAQ investigating safety professionals essentially
become “building whisperers,” tracking the entry, exit, and flow of air through buildings along with any flow impediments and heating and cooling system ele- ments. Proper operation of building heating, cooling, and ventilation systems (HVAC) is critical to satisfac- tory indoor air quality.
Building HVAC systems or recirculating systems with controlled fresh air intake volume. Heating and cooling of HVAC air is a large annual expense, which some facilities attempt to reduce by limiting the amount of incoming fresh air during the peak heating and cooling seasons. Reduced fresh make up air can result in odor build up and increasing indoor carbon dioxide levels, generated by occupants and/or combus- tion sources, resulting in symptoms and complaints.
Exposure Limits
OSHA and other industrial carbon dioxide (and carbon monoxide) exposure limits are not suitable exposure comparisons for office occupancies. The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) has developed Standard 62.1 Ventilation for Acceptable Indoor Air Quality which is part of many U.S. building codes.
The standard’s objective is the publication of mini- mum ventilation rates and other measures to support acceptable human indoor air quality and minimize adverse health effects in new and existing buildings. The standard sets a suggested maximum carbon di- oxide level not to exceed 700 parts per million (ppm) above exterior background concentrations, usually around 405 ppm.
The sensitive population often begins to com- plain when interior carbon dioxide levels rise to 800 to 1,000 ppm. Exterior carbon dioxide levels increase slightly each year due to expanding carbon footprint and in Mid Atlantic U.S. region, have increased from 350 ppm to 405 ppm over the past 30 years, a sustain- able concern.
Fresh make up air can be increased via electronic or manual HVAC damper adjustment. Even when tightly closed, as much as five percent fresh make up air can still enter an HVAC system from negative pres- sure draw. Increasing fresh make up air often solves as many as half of all IAQ complaint scenarios dem- onstrating that indeed, “the solution to pollution is dilution.” Increasing carbon dioxide levels can also be generated by poorly controlled sources of combustion and both carbon monoxide and carbon dioxide levels should always be monitored together. Increasing fresh
80 Occupational Health & Safety | SEPTEMBER 2019
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