Indoor Air Pollution

A Common Myth Air pollution occurs only outdoors Or In industrial environment Truth!!!! What is more agreeable than one’s home? Feeling safe ? Away from outside pollution ? Air inside the conditioned space can be substantially more polluted than outdoor air.  Historical Perspective First indication of indoor contamination – Asbestos pollution, a carcinogenic substance, discovered by epidemiologists, used in almost all building materials about 35 years back.Banned due to adverse health effects NOT considering IAQ. Concept of IAQ first introduced among scientific community in 1980 due to some occurrences of ‘episodes indoors’. At central headquarters of EPA building at Washington, D.C.- more than 100 people fell sick within 15 minutes of entering the office. In Los Angeles, CO level in most of the well insulated buildings was three times greater than the outside level.  Outcome Such episodes indoors in developed nations ended up with 1. Extensive monitoring programme development indoors 2. Identification of indoor contaminants 3. Formulation of IAQ models 4. Development of control methodologies 5. Formulation of Indoor Air Contamination Standards. 6. Identification of ‘Sick Buildings’ 7. Investigation of ‘Sick Building Syndrome(SBS)’  What is IAQ?? IAQ stands for “Indoor Air Quality” It refers to the nature of the conditioned (heat/ cool) air that circulates throughout space/area, where we work and live i.e. the air we breathe most of the time (almost 80 % of the time).  What Causes Indoor Air Pollution?? Air tightness of buildings Poorly designed air conditioning and ventilation systems Indoor sources of pollution Outdoor sources of pollution  Air Tightness in BuildingsCauses inadequate supply of fresh air, as a result, negative pressure develops, which causes Ground level pollutants, e.g. CO, Radon etc.to be drawn inside the buildings. Release of odor (Bioaerosols) and other pollutants. Pull outside polluted air from vents, cracks and openings and increase dust, pollen etc. Causes “Sick Building Syndrome”.  Poorly Designed Air Conditioning Systems Results into the production of fungi, molds and other sickness causing microbes.  Problems of IAQ Enclosed spaces inhabited by humans produce following effects- Reduction in oxygen level of spaces. Increase in CO2 level. Increase in temperature. Increase in humidity Increase in Bioaerosols and odor  Sources of Indoor Air Pollution in a Typical Office Building  Sources of Indoor Air Pollution in a Typical Household  Hard Facts Fresh air contains 21.0% (v/v) O2 Exhaled air contains 17.0% (v/v) O2 and 83.0 % (v/v) CO2 An adult emits 45 gm sweat / hour containing bioaerosols. An adult produces 300 BTU of heat / hour. Carbon based gaseous pollutants (VOCs) indoors are 2 to 5 times higher than outdoors.  Poor IAQ Results  Indoor Air Pollutants and Their Health Effects Pollutant Effect Limits NOz Type: Immediate Causes: irritation to the skin, eyes and throat, cough etc. 0.05 ppm (avg. over one year for 8 hours exposure daily)- EPA CO Type: Immediate Causes: headache, shortness of breath, higher conc. May cause sudden deaths. . 9.0 ppm (avg. over 8 hours period)- EPA RSPM Type: Cumulative Causes: Lung cancer 150 µg/ m3 (24 hr. average) SO2 Type: Immediate Causes: lung disorders and shortness of breath 0.05 ppm (avg. over one year for 8 hours exposure daily)- EPA Radon  Type: Cumulative Causes: Lung cancer  >/ 4 pCi/ Litre of indoor air Formaldehyde  Type: Immediate Causes: irritation to the eyes, nose and throat, fatigue, headache, skin allergies, vomiting etc. 120 ? g/ cu.m. (continuous exposure)- ASHRAE Asbestos  Type: Cumulative Causes: Lung cancer >/ 2 fibers/ cu.cm. Of the indoor air (8 hrs. exposure period)- OSHA Pesticides Type: Immediate Causes: Skin diseases   VOCs Type: Immediate Causes: Liver, kidney disorders, irritation to the eyes, nose and throat, skin rashes and respiratory problems. Not for all VOCs. For chlordane: 5? g/cu.m.(continuous exposure)) CO2 Surrogate index of ventilation 1000 ppm O3 Type: Immediate Causes: eyes itch, burn, respiratory disorders, lowers our resistance to colds and pneumonia. 100 ? g/cu.m (continuous exposure)- OSHA  WHO Standards Pollutants Concentration reported Concentrations of limited or no concern Concentration of concern Remarks Respirable particulates 0.05 – 0.7 <0.1 >0.015 Japanese standard 0.15 mg/cubic m CO 1-1.5 <2 >5 Indicator for eye irritation(only from passive smoking) NO2 0.05 – 1 <0.19 >0.32 ------ CO ---- 2% CO Hb 3%COHb 99.9% 1-100 < 11 >30 Continuous exposure Formaldehyde 0.05 – 2 < 0.06 >0.12 Long- and Short- term SO2 0.02 – 1 < 0.5 >1.35 SO2 alone, short-term CO2 500 – 5000 ppm < 1000 ppm >1000 ppm Occupancy indicator O3 600-9000 < 1800 >12000 Japanese standard 1800 mg/cubic m   <10 fibres/cubic m ~ 0  fibre/m  For long Exposure * typical ranges of concentration is given in mg/cubic m, unless otherwise indicated Parameters Affecting IAQ Rate of exchange of air from outdoors (ventilation) Concentration of pollutants in outdoor air Rate of emission from sources indoors Rate of removal of pollutants (Sinks) Indoor temperature Indoor humidity Age of indoor structure Type of foundation soil  Steps for Investigating IAQ Problems Document employee health complaints. Examine floor plans and ventilation system specifications. Analysis of data collected from above steps for SBS score calculations. Study of building layout, position and location of windows, doors, vents, openings etc. Ventilation measurement. Monitoring of indoor pollutants and other environmental parameters and development of IAQ model. Develop a plan for reducing and eliminating the IAQ problem  What is Ventilation?? A process, whereby air is supplied and removed from an indoor space by natural or mechanical means.  Why ventilation is needed indoors? To remove heat or moisture OR to reduce the concentration of one OR more indoor pollutants  Types of Ventilation  Natural  Mechanical Natural Ventilation Involves Infiltration: random/ intentional flow of outdoor air through windows, cracks and a variety of openings in the buildings. Exfiltration: movement of air from indoor spaces to outdoor. Limitation of Natural Ventilation Fairly inefficient as it is NOT UNIFORMLY distributed. Air doesn’t circulate evenly and stale air gets collected in some dead end spaces. It brings POLLENS & OTHER POLLUTANTS from outside air. Maximum energy loss occurs as NO CONSERVATION of energy can be done Mechanical ventilation It involves use of fans and heating / air conditioning equipments. Principle of mechanical ventilation Pulling fresh air from outside to indoor spaces. Exhaust stale air. Control temperature and humidity inside.  Ventilation Measurement A. In naturally ventilated buildings By Infiltration measurement.Infiltration is reported as air change per hour (ACH) – the average rate at which indoor air is replaced by fresh outdoor air.ACH is a rough guideline for different building conditions, given by ASHRAE. For e.g., in “air tight buildings” ACH is 0.1 to 0.2, in “leaky building”, ACH is 2.0 to 3.0. ASHRAE model for measuring infiltration in naturally ventilated buildings is – I = ln (CO / Ci) / t Tracer gas technique is employed to measure infiltration. Non reactive gases, e.g. SF6/NO are used as tracer gases with the assumption that the loss of tracer gas is only due to ventilation/ exfiltration. B. In mechanically ventilated buildings ACH is measured by CO2 concentration. It is a good surrogate index to determine the proper ventilation in HVAC buildings. ASHRAE model for measuring infiltration in HVAC buildings is –Q = G/ Ci – Ca Minimum recommended ventilation rate by ASHRAE is 8L/sec. per person to maintain the indoor concentration of CO2 as 700 ppm. Parameters for Natural Ventilation Air Flow- occurs mainly due to two driving forces 1. Pressure Gradient – Difference in outdoor and indoor pressure (varies with building shape, size, openings, wind direction, local environmental densities, neighbour building’s configuration, topography etc.) 2. Temperature Gradient (Buoyancy Forces)- when the inside air temperature is higher than outside air, the warm air at floor surface starts rising and the cool air starts entering as a result of vaccum created at floor surface. This effect is called as “Stack Effect”. Parameters for Mechanical Ventilation Infiltration air Exfiltration air Recirculated air Exhaust air Makeup air What is sick building syndrome? The feeling of illness among majority of occupants of a conditioned space is called “Sick Building Syndrome”. A variety of illness symptoms reported by occupants in sick buildings are – Headache, fatigue, irritation in eyes, nose and throat, shortness of breathe etc. Causes Inadequate ventilation – insufficient supply of outside air; poor mixing; fluctuations in temperature & humidity; air filtration problem due to lack of maintenance of HVAC systems. The CO2 level indicates the ventilation efficiency of buildings. Building shows SBS symptoms, if CO2 concentration > 1000 ppm.  About The building How old is the building? What construction materials have been used? How many floors in the building? How many square feet per floor? What types of windows are in the building? Do they open? Who is responsible for the functioning of the building systems? Who is responsible for cleaning the interior of the building? How often is the building cleaned? Have there been any major renovations or operating changes ? What are they ? When did they occur? Does the building have sprayed or foamed insulation? When was it applied? What type of heating system is used? What type of cooling system is used? What type of humidification system is used?  How is the total ventilation system operated? What floors and rooms are served by each system? What type of filtration system is used? How often it is changed or maintenainced? How much fresh air is being introduced into the ventilation system? Does this amount meet system specifications? Where are the fresh air inlets? Are they functioning properly? Are there any possible sources of contamination located in the general vicinity of the air inlets? How likely are contaminants to be drawn into the air inlets due to prevailing winds and inversions? How does exhaust air leave the building? Is the building being used for the same purpose for which it was designed? What type of activities are buliding occupants engaged in? What processes or activities are present in the building that may serve as contaminant sources?Is locla exhaust ventilation used near contamination sources?  Employees Questionnaire What health complaints have experienced at work? Do you have any of the following conditions? Hey fever _______ Other allergies ________ Dermatitis or other skin problems______ Sinus problems______ Cold or Flu______ Naussea or dizziness____ Eye irritation________ Headache______ Excess fatigue______ Joint aches_____ When did you first noticed these symptoms? When do the symptoms occur? How often? Do your symptoms clear within an hour of leaving work?If not, which symptoms persist through the week? Are the symptoms more likely to appear at particular times of day? Do they occur in the particular areas of the building? How many co-workers smoke? Do they smoke? Is there a specific incident to which your health problems can be traced( ie building renovations, installation of new carpets,purchase of new furniture) What office machines are used in your vicinity? What chemicals do they use? What office products are used that contain chemicals?List the ingredients? What fabrics are used in the carpets,curtains, shades and wall coverings? Is there any evidence of excessive dust or mold? Are you aware of any water leakage that have not been repaired so far? What is your overall assessment for the air quality and confort level in your office? Do you work with any office equipment? Specify the type? Where is your office located? Specify floor, department, and proximity to office equipment ? How old are you? What is your job title? Briefly describe your responsibilties? Whta is the general condition of your health? Is there any family histroy or illness?