Presentation on theme: "Indoor Air Quality Case Studies Kevin Renton. IAQ Intro – why this stressor is important The problem i.e. Health effect Legislation / Directives – incl."— Presentation transcript:
IAQ Intro – why this stressor is important The problem i.e. Health effect Legislation / Directives – incl. OEL, what guides us / restricts us How measured How controlled Challenges How practical/applicable to measure/assess Wrap up
9(2). Every employer who uses any hazardous chemical substance at work, shall be in possession of a copy of Annexure 8, or a copy of sufficient information, as contemplated in sub regulation (1).Annexure 8, containing all the information as contemplated in either ISO 11014 or ANSIZ400.1.1993 with regard to— 16 sections of a MSDS i.e. sufficient information to ….. take the necessary measures …for…protection of health and safety
Reg 6. Assessment of potential exposure. An employer or self-employed person shall after consultation with the relevant health and safety representative or relevant health and safety committee, cause an immediate assessment to be made…..
Hazardous Biological Agents Regulations (Sect 4) “cause a risk assessment to be made”.. if any person might have been exposed to a HBA; classification of the HBA into the relevant risk group, record for 40 years, Information etc
OHSAct; General duties of employers (Sect 8)...establish what safety or health hazards are attached to any work, any article or substance, and any plant or machinery+ establish & provide the necessary precautionary measures HCSRegs Assessment (Sect 5) Two yearly assessment of exposure in writing HCS involved and it s health effects; where it is located; its form the route of intake; the extent of intake; the process involved; and the effect of a failure or deterioration of existing control measures
eyes, nose, and throat irritation, headaches, dizziness & fatigue
SeasonParameterMeasurement Winter or SummerCO 2 Less than 1000ppm WinterTemperature20-24°C SummerTemperature23-26°C Winter or SummerHumidity30-60% RH Table 1: Acceptable Indoor Air Quality – ASHRAE Good practice guidelines suggest an air velocity of at least 0.1m/s. The National Building Regulations, SANS 10400-1990, also requires that, in order to prevent the perception of draughts, the air velocity of air in an occupied room should not exceed 0.5m/s.
ParameterReference valuesSource Temperature 23-26 °C ASHRAE Standard 62-1989, 1992 Humidity30-60% RH ASHRAE Standard 62-1989, 1992 Carbon Monoxide8 hour 9 ppmASHRAE Standard 62-2000 Carbon Dioxideless than 1000 ppm ASHRAE Standard 62-1989, 1992 Number of air changes/hour 6 air changes/hour: officesD. Jeff Burton 8-12 air changes/hour: medical centre & medical offices Engineering toolbox – see references below Total air supply required per person 10 L/s ASHRAE 62-2001 ComfortLess than 10% complaining of any one thermal condition- hot/cold/stale/humid ASHRAE 55 GUIDELINES USED
ContaminantTypical sourcesLevel of interestComments Carbon monoxide (CO) Leaking vented combustion appliances Unvented combustion appliances Parking garages Outdoor air 3 ppm above outdoor level 9 ppm(health) Mental alertness level an indication of abnormal indoor concentration; investigation of possible sources advisable Health level based on effects on persons with coronary artery disease, average exposure for 8 hours over a working lifetime. Formaldehyde (HCHO) Pressed wood products Furniture and furnishings 120.μg/m ³ ( 0.1 ppm) Based on irritation of sensitive people, 30 minute exposure(WHO). Lead (Pb)Paint dust Outdoor air 1.5 μg /m ³ Based on adverse effects on neuropsychological functioning of children, average exposure for 3 months (WHO: 0.5-1 μg/m ³ for 1 year) Nitrogen dioxide (NO2 ) Leaking vented combustion appliances Unvented combustion appliances Outdoor Air 100μg/m ³ Based on providing protection against adverse respiratory effects, average exposure for one year
OdorsOccupants Fungal ( mold ) sources VOC sources Outdoor air Predicted acceptability to 80 % or more of occupants or visitors CO2 concentration can be used as a surrogate for occupant odor (odorous bioeffluents ). For sources other than people, source control is recommended. Ozone (O3)Electrostatic appliances Office machines Ozone generators Outdoor air 100μg/m ³ ( 50 ppb) Based on potential for adverse acute and chronic effects and an additional margin of protection, 8 hour exposure. Particles (PM10) Dust Smoke Deteriorating materials Outdoor air 50μg/m ³ Based on protecting against respiratory morbidity in the general population and avoiding exacerbation of asthma, average exposure for one year, no carcinogens. Indoor concentrations are normally higher than outdoor concentrations, the guideline level may lead to unacceptable deposition of dust.
ContaminantTypical sourcesLevel of interestComments Radon (Rn)Soil gas4 pCi/literBased on lung cancer, average exposure for 1 year. Sulfur dioxide (SO2) Unvented space heaters ( kerosene) Outdoor air 80μg/m ³ Based on protecting against respiratory morbidity in the general population and avoiding exacerbation of asthma, average exposure 1 year. Total volatile organic compounds ( TVOC’s) New building materials and furnishings Consumable products Maintenance materials Outdoor air < 300μg/m ³ - comfort range complaints unlikely 300- 3000μg/m ³ - complaints possible >3000μg/m ³ - discomfort range, complaints likely > 25000μg/m ³ - toxic range Odor and irritation responses to organic compounds are highly variable. The three guidelines for this class of compounds represent ranges where odor and irritation complaints are seldom observed (comfort range); where complaints become significant in buildings (comfort/discomfort range); and where significant complaints are likely (discomfort range). Average indoor concentrations in most buildings are well below 1000μg>m ³. The value for design should be selected by the designer and the owner of the building. During the operation of the building, measured TVOC concentrations above 1000μg>m ³ should trigger further analysis to determine whether concentrations of individual compounds are above levels of concern. Above 25 mg/m ³ additional neurotoxic effects other than headaches will occur.
Are these complaints suggestive of a biological contamination of some sort? What complaint rate is suggestive of a real IAQ problem?
The IH took note of the odour complaints – most were suspiciously similar to complaints associated with microbiological problems. After conducting a survey, the IH determined that 33% o0f people were complaining. This was high – typically less than a few percentage of people would have such complaints. Complaints had begun in May, as warm weather hit the region.
What potential sources would the IH investigate (and eliminate )?
The IH was able to discount some possible odour sources right away – there had been no flooding or water damage episodes, no construction or remodelling was going on, no equipment was malfunctioning, there were no open chemical processes in the building and smoking had been outlawed several years ago.
What would be likely source of these complaints, given that complaints were isolated to two floors and complaints began at the beginning of summer?
Because no obvious source was quickly identified, the IH next turned to the air handling unit (AHU) and found that a dedicated AHU on the roof served both the 9 th and 10 th floors.
The IH routinely checked air flows at the supply and return registers in each office, with the following results: Air turnover rates seemed adequate, about 7 air changes/hour Outdoor air was being provided at about 10% of total supply, (typical of operations during the hot, humid summer months)
Indoor air temperatures and humidities were at the upper end of normal: 23- 24 deg C 55-65% relative humidity Indoor carbon dioxide samples were not abnormally high – av 900ppm Outdoor air concentrations of carbon dioxide av 370ppm
The IH also inspected the rooftop AHU equipment with the following results: All ductwork and connected controls were attached and operating properly The air filter system consisted of a roll type prefilter (MERV=5) and a bank of 2’x2’ pleated paper filters (MERV=10)
The roll filter had become defective during the winter and the filter removed until repairs could be made The 2’x2’ filter bank had 3 pleated filters missing and air was flowing unfiltered into the AHU through holes
HAZARDOUS BIOLOGICAL AGENTS (HBAs) RISK ASESSMENT REPORT Lab handling TB specimens :- culturing and identifying Third case of TB in this Lab ! (in 7 years)
MERV- filter efficiency MERV, - Minimum Efficiency Reporting Value, 1 to 16 relative to an air filter’s efficiency..Minimum Efficiencyair filter’s efficiency lower efficiency e.g. a fiberglass panel filter may have a MERV of 4 or 5.lower higher efficiency e.g. a MERV 14 filter is typically the filter of choice for critical areas of a hospital (to prevent transfer of bacteria and infectious diseases).higher
TABLE 1. Air changes per hour (ACH) and time required for removal efficiencies of 99% and 99.9% of airborne contaminants*
Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005 Please note: This report has been corrected and replaces the electronic PDF version that was published on December 30, 2005. Recommendations and Reports December 30, 2005 / 54(RR17);1-141 Prepared by Paul A. Jensen, PhD, Lauren A. Lambert, MPH, Michael F. Iademarco, MD, Renee Ridzon, MD Division of Tuberculosis Elimination, National Center for HIV, STD, and TB Prevention
* Short-circuiting is the passage of air directly from the air supply to the exhaust Room airflow patterns designed to provide mixing of air and prevent short-circuiting*
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr54 17a1.htm?s_cid=rr5417a1_e#tab1 http://www.cdc.gov/niosh/topics/healthcare/ http://www.infectioncontroltoday.com/articles/1 61inside.html Control Solutions
Occupants along the west wall of an office building complained of "odors, dust, smoke, cold air, and noise." Several had asked to be transferred to other areas. An Occupational Hygienist investigated.
Figure 1. Plan View of Office Building Area of Complaints Showing Locations of Thermostats (T), and Air Handler No.1 (AR1) on the Roof; North is Up
The space characterization data gathered by the IH included : The office space consists of offices along the outside walls of the single story building.. A large package-unit AHU was located on the roof; the system was a reheat type unit with supply and return ducts. The floor area was 5,000 square feet. A total of 35 people work in the office area.
The IH's walkthrough and investigation data included:. The office building was divided into four zones; air was supplied to each office space from supply registers in the ceiling and returned at ceiling grilles.. Thermostats were located in four locations in the hallways. Each was locked and only the HV AC operator had the key. Temperatures were set by "consensus."
The total amount of air, Q, being delivered to the space was QSA = 2,500 cfm; percent OA 30%; the amount of air being returned to the AHU, QRA = 3,000 cfm.. Average indoor measured dry bulb temperature = 23° C; range = 20 -24°C; RH = 30-50%. 70 792 litre/min 33 l/s person
Using indicator tubes, CO = 0 ppm and CO2 = 900 ppm. Other: Odours and dust were observed in offices along the west wall. Water had infiltrated the roof of the building during a severe storm two months ago. A new building was being constructed on the west side of the building. Outside: Stormy; west winds at 10 mph, outside temperature, 40°F, RH, near 100%. Building construction: Concrete block; aluminium windows; 25 years old.
.. The building was quiet dusty; housekeeping was performed weekly during the evenings.. The AHU had no provision for humidifying the air.
Please evaluate the above data and write your- responses to the following questions 1. Was there a genuine IAQ problem? 2. Were the following IAQ-related parameters okay/not okay? Air distribution? Total air volume flowrates? OA delivery?
Carbon Dioxide Concen trations? Thermal Comfort conditions? Air contaminants? Air contaminant concentrations? HV AC problems?
What do think may be the sources and/or causes of the complaints?
Outcome. These were the findings and recommendations for control:. Temperatures, RHs, CO, CO2, QOA, thermostat locations, supply and return registers-all appeared within normal and acceptable criteria. Dust, odors, temperature extremes, and noise suggested a genuine IAQ problem. QRA = 3,000 cfm and QSA =2500 cfm. The building was under negative pressure because more air was being returned to the AHU than being supplied to the building. (Should be positive.). Air was infiltrating the building along the walls, especially the west wall because the wind was from the west.. Construction dust, odours, noise, and cold air were infiltrating the west wall.
Recommendations for control: -- Rebalance the HV AC system to bring the building into a slight positive pressure (re: the outside). -- Maintain tight control of remodeling /renovation activities in the future.
INDOOR AIR QUALITY SAMPLING WORKSHEET Room number and description CORHTEMPCO2 Comments ppm% °C ppm Office worker 10.928.222.5918 Open plan office, which accommodates about 36 people. The air-conditioning system used does not introduce fresh air from the outside rather it recirculates the air from inside the building. The office has carpet flooring, that has to date this year been washed only once and it is vacuumed every second day with a vacuum cleaner fitted only with an ordinary dust filter. The partitioning on the workstation has cotton fabric on it. The office has openable windows but they are seldom opened and they were not opened on the day of the assessment. The office has about 4 pot plants. Smoking was observed on 2 of the 4 balconies. Office worker 20.627.722.7958 Office worker 30.728.222.6969 Office worker 40.628.022.4963 Outside (back of building by fire escape door)0.118.220.9369 Outside (front of building by entrance)0.112.526.0348
INDOOR AIR QUALITY SAMPLING WORKSHEET Room number and description CORHTEMPCO2 Comments ppm% °C ppm Microbiology/ recieving0.124.321.6776 Store room0.023.321.5675 Flow cytometery0.021.321.2556 Lab Manager0.020.421.0519 Tea room0.021.220.8532 Medical Laboratory
The air velocity measurements did not comply with the minimum standard of at least 0.1m/s in approximately half of the areas that were evaluated. The maximum air velocity of 0.5m/s was not exceeded in any of the rooms.
Recommendations “Once the modifications have been implemented, employees should be trained how to maintain the proposed temperature adjustment” Involve the Engineer in the H&S Committee – Team approach Including MANAGEMENT. Changing Office plans not considering fresh air requirements
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