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Indoor Air Quality: Study of Chemical Pollutants Building and Industry Department
Training period: March 11th – September 8th 2006 Supervisor: Mr. Sergio G.FOX, building engineer and consultant Aurélie BARRET Master 2 CPRE Orléans
ACKNOWLEDGEMENTS I would like to thank I would also thank a lot Sergio Fox, my supervisor, for the interesting different projects and the responsibilities he charged me of during this six-month period; for having discovered me the consultancy field; for all his ideas concerning the project including a website and an interview with the Danish EPA; and of course for his kindness and cheerfulness. Thank to I would also thank all the people from the Building Department especially room 3G, for their welcoming and for having discovered me another society. It was really enriching both on a personal point of view and on a professional one. Thank to Jacqueline Anne Falkenberg from the Environmental Department for her help during air sampling in the office room. Finally, thank to Christophe Guimbaud, my supervisor at the CONTENTS
INTRODUCTION 3 1. PRESENTATION OF NIRAS 4 1.1 General presentation 4 1.2 Building and Industry Department 4 1.3 My experience in NIRAS 4 2. INDOOR AIR QUALITY 5 2.1 Definition 5 2.2 Types of indoor air pollutants 5 Ø Chemical pollutants 5 Ø Physical pollutants 5 Ø Biological pollutants 5 2.3 Indoor chemical pollutants 6 Ø Nature 6 Ø Sources 6 Ø Transport 7 Ø Temporal and spatial variation 7 2.4 Health problems 7 2.5 Cost of indoor air pollution 9 3. INDOOR ENVIRONMENTS STUDIED 10 3.1 Spa project in Ø Context 10 Ø Chlorination and health problems 10 Ø Alternatives to chlorination 12 Ø Situation in 3.2 Analysis in a workplace environment 14 Ø Description of the room 14 Ø Sampling 14 Ø Results of the air sampling 14 Ø Conclusion 15 4. SOLUTIONS FOR A GOOD INDOOR AIR QUALITY 16 4.1 Source control 16 4.2 Ventilation / Dilution 17 4.3 Air treatment 18 Ø Absorption by building materials 18 Ø Photo-catalytic oxidation 18 Ø Indoor plants 19 4.4 My “ideal building” 20 CONCLUSION 21 REFERENCES 22 APPENDICES 25
INTRODUCTION
Most people are aware that outdoor air pollution can damage their health but may not know that indoor air pollution can also have significant effects. Indeed, the level of some indoor air pollutants can be two to five times, even one hundred times, higher than outdoor levels. These levels of indoor air pollutants are of particular interest because it is estimated that most people spend as much as 90% of their time indoors that is to say in homes, office buildings, shops, schools, transports, restaurants… Indoor air pollution kills 1,6 million people each year – one person every 20 seconds – and 2 billion more are at a risk. It kills more people than malaria and nearly as many as unsafe water and poor sanitation.
The indoor air pollution has increased in the last decades due to several factors: the increase of rural and urban concentrations of tropospheric ozone, the increase of the use of terpenes (fragrance products), the construction of homes and offices tighter, and the decrease of ventilation rates (because of the cost of energy). And unlike outdoor air, indoor air is recycled again and again. This causes it to trap and build up pollutants. In that way, to prevent and control indoor air pollution, sources of the indoor air pollutants have to be known. Besides, technical solutions to improve indoor air quality have to been studied. These different points are the subject of this training period. However, the chemical pollutants are the only indoor pollutants studied. Thus, the firm where I carried out my training period will be first presented. Then an introduction about indoor air quality (definition, types of indoor air pollutants, health problems and cost) will be done. In another part, two types of indoor environments will be studied: the air quality for a spa project and the air quality in an office room. Finally, technical solutions for a good indoor air quality will be proposed and an “ideal” building for a good indoor air quality will be suggested. 1. PRESENTATION OF NIRAS 1.1 GENERAL PRESENTATION NIRAS is a large consulting engineering Danish company created in 1956. The firm counts currently 900 employees (650 in NIRAS is specialized in engineering and consultancy in different areas:
1.2 BUILDING AND INDUSTRY DEPARTMENT (in Allerød, DK) In this department, 211 people were working in 2004 (142 engineers, 1 academic, 26 technicians and 42 assistants and secretaries). For my part, I worked in the building division with people specialized in indoor climate, acoustic, fire safety, ventilation, structure conception, heating and cooling systems, lighting and environmental planning. They assist the customers at every stage of a construction project (economic planning, conception, management, evaluation and construction). Furthermore as engineers-councillors, they have to assure the best quality of buildings by proposing the most economical and adequate solutions. There are 7 specialists in indoor climate in the building division. Their work consists in bringing ecological solutions to problems met in buildings (ventilation, air-conditioning, heater…). This search for solutions is based on the new available technologies, on the various existing materials on the market, on the solution adapted to the case (to avoid over-dimension), on the multifunction that the elements of a building can have… The projects carried out by NIRAS in indoor air are diverse: the Danish Pavilion (world exhibition in 1.3 MY EXPERIENCE IN NIRAS My experience started on 13/03 until 09/09. During this training, oral presentations were carried out every two or three weeks in front of few people from NIRAS. Two presentations were also made for the spa project (a private presentation and then a public one). An interview of a person from the Danish EPA and some phone interviews were done. A website was created (www.aurelie.dk) and the different projects lead can be seen on it, including summaries and the PowerPoint presentations. This experience was very enriching. I have learned a lot about the subject (indoor air pollution) but also about the way of work in a consultancy company. It gave me the envy to continue in this field. I was very fascinated by certain projects (e.g. air treatment by plants). The major barrier I have met is the language (danish). Besides, at first it has needed some adaptation to work with non-chemists. Finally, my lack of knowledge in construction and the non-registration of the firm to chemical revues were sometimes a “handicap”.
2. INDOOR AIR QUALITY (IAQ) 2.1 DEFINITION OF IAQ The Indoor Air Quality (IAQ) is the term used to describe the nature of the air inside enclosed areas that could affect health and comfort of occupants. [1] The enclosed areas can include offices, classrooms, transport facilities, shopping centres, hospitals, homes… IAQ is a constantly changing interaction of complex factors that affect the types, levels and importance of indoor air pollutants. These factors include the sources of pollutants or odours; design, maintenance and operation of building ventilation systems; moisture and humidity; and occupant perceptions and susceptibilities. [2] In addition, there are many other psychological factors that affect comfort or perception of IAQ. A more technical definition of IAQ is related to how well indoor air satisfies the three basic requirements for human occupancy: ü Thermal acceptability ü Maintenance of normal concentrations of respiratory gases ü Dilution and removal of contaminants to levels below health or odour discomfort thresholds Indoor air quality in an environment is thus described by the concentration of the indoor pollutants. Nevertheless, there is not currently any national or international legislation for pollutants levels in indoor environment. There are some guidelines proposed by some organizations, for example in 2.2 TYPES OF INDOOR AIR POLLUTANTS The major types of indoor pollutants are chemical, physical and biological. There is considerable connection between these categories since gases can form particles or be adsorbed to particle surfaces. [3]
Example of sources of chemical pollutants: paints
Physical pollutants include particles, fibres and biological aerosols. Particles come from stoves, heaters, fireplaces, chimneys and tobacco smoke. The most known fibres are asbestos. That is the name given to a group of microscopic mineral fibres that are flexible and durable and will not burn. Asbestos fibres are light and small enough to remain airborne. They are found in roofing and flooring materials, wall and pipe insulation, cement, coating materials, heating equipment and acoustic insulation. It may become a potential problem indoors only if the asbestos-containing material is disturbed and become airborne, or when it disintegrates with age. [3, 4]
Dust mite 2.3 INDOOR CHEMICAL POLLUTANTS
As it was said before the indoor chemical pollutants commonly found in indoor environment are the following ones: CO, CO2, NO, NO2, O3, VOCs, aldehydes, SO2, pesticides and radon. The majority of them can also be found in outdoor air. There is metabolic product (CO2), inorganic combustion gases (CO, NOx and SO2), product of photochemical reactions (O3), organic compounds (VOCs, aldehydes), radioactive gas (radon) and varied compounds (pesticides). [5]
Indoor air contaminants can originate within the building or be drawn in from outdoors. If contaminant sources are not controlled, IAQ problems can arise. Four categories of sources can be drawn up: * Outdoor sources: industrial pollutants, exhaust from vehicles, pesticides, radon… * Sources from the building equipment: building material, stoves, heaters, fireplaces, carpets, curtains, computers and other office equipment, air cleaning device, clothes dryers, wall coverings, floor coverings, furniture… * Sources from human activities: body products, household products, cooking, smoking, painting… * Indoor chemical and physical reactions: ozone/terpenes reactions, re-suspension… First the combustion products (CO, NO, NO2) come from kerosene heaters, un-vented gas stoves and heaters, charcoal broiling, candles, clothes dryers, exhaust from automobiles in attached garages, glues, hobby supplies, furnaces and chimneys, oil and kerosene lamps, tobacco smoking and outdoor air. The sources of SO2, other combustion product, are mainly fossil fuel appliances and furnaces. Ozone can result from outdoor air, photochemical reactions (with NO2 and the VOCs), computers, photocopiers, printers, fax machines, electronic air cleaners and office equipments that use electrostatic process, and ionizer sold as air freshening or air cleaning device. The organic compounds, VOCs and formaldehyde (the aldehyde the most studied) can come from a lot of sources: adhesives, air fresheners, carpets, candles, charcoal broiling, clothes dryer, exhaust from vehicles in attached garages, gas water heaters, glues, hair sprays, oil and kerosene lamps, paint strippers and outdoor air. VOCs can also result from aerosol sprays, computers, correction fluids, copiers, cleansers, deodorizers, disinfectants, dry-cleaned clothing, fax machines, printers, lacquers, paints, paper products, permanent markers, permanent press clothes, plastic products, subflooring, varnishes, vinyl flooring and wax. For its part, the formaldehyde has other sources such as cosmetics, curtains, dyes, floor polish, foam insulation, gas stove, moth repellents, perfumes, particleboard, hardwood plywood panelling, medium density fibreboard, synthetic carpeting, tobacco smoking, upholstery, wall coverings, wood preservatives and indoor chemical reactions between ozone and fragrance compounds (especially terpenes). The most common source of indoor radon is uranium in the soil or rock on which homes are built. As uranium naturally breaks down, it releases radioactive radon gas. Radon gas enters homes through dirt floors, cracks in concrete walls and floors, floor drains and sumps. Sometimes radon enters the home through well water. Residential pesticides represent a broad class of chemicals and applications aimed at controlling flies, ants, moths, cockroaches, fleas, ticks, infectious organisms, fungi and other unwanted species in and around the residential environment. Pesticides that have been measured in indoor air include chlordane, heptachlor, aldrin, dieldrin, diazinon, propoxur, dichlorvos, naphthalene, p-dichlorobenzene, pentachlorophenol, chlorpyrifos, malathion and carbaryl. They usually reach occupant breathing-zones by travelling from the sources to the occupants by various pathways. They travel with the air flow that is to say from areas of high pressure to areas of low pressure. That is why controlling building air pressure is an integral part of controlling pollution and enhancing building IAQ performance. One should focuses on driving forces and pathways. Major driving forces include the wind, stack effect, HVAC/fans, flues and exhaust, and elevators. The major indoor pathways include stairwell, elevator shaft, vertical electrical or plumbing chases, receptacles, outlets, openings, duct or plenum, duct or plenum leakage, flue or exhaust leakage, and room spaces. The major outdoors-to-indoors pathways are through indoor air intake, windows and doors, cracks and crevices, substructures and slab penetrations. [3]
An important characteristic of indoor air pollutants is that their concentrations vary both spatially and temporally to a greater extent than in common outdoors. This is due to the large variety of sources, the intermittent operation of some of the sources and the various sinks present. Concentrations of contaminants that arise principally from combustion sources are subject to very large temporal variation and are intermittent. Episodic releases of VOCs due to human activities such as painting also lead to large variations in emission with time. That is the same with formaldehyde released from wood-based products. Emissions from furniture components or paints decreased slowly over the time, following a power-law decay curve. In some cases, variations are influenced by temperature and humidity fluctuations or by ventilation conditions. Globally, emissions from a source decreased with the age of the source. Besides, it has been shown through studies that emissions in a tested room were lower in summer than in winter because of natural ventilation more important in summer (windows opened). [5, 6, E] Spatial variations within a room tend to be less pronounced than temporal variations. Within a building, there may be large differences in the case of localized sources such as photocopiers and printers in a central office, gas cookers in the restaurant kitchen, smoking areas … [5, 6] Globally, the emissions will be higher in rooms with a lot of furniture (especially new products, wood products manufactured with UF resin and office equipment), humans (human activities), combustion sources (wood stoves, gas stoves, and tobacco smoke) and fragrance products.
2.4 HEALTH PROBLEMS As it was said before we spend about 90% of our time in indoor environments and the concentrations of the pollutants measured there can be two to five, even hundred times, higher than outdoors ones. Unfortunately, indoor air pollutants give no warning and produce symptoms sometimes similar to those from cold or other viral diseases. They can also produce symptoms years later, when it is even harder to discover the cause. In addition, people who may be exposed to indoor air pollutants for the longest periods of time are often those most susceptible to the effects of indoor air pollution. Such groups include the young, the elderly, and the chronically ill, especially those suffering from respiratory or cardiovascular diseases. Thus, the age and the pre-existing medical are two important influences. Besides, there is an uncertainty about what concentrations or periods of exposure are necessary to produce specific health problems. People react very differently to exposure to indoor air pollutants depending on individual sensitivity. Some people can become sensitized to biological pollutants after repeated exposures, and it appears that some people can become sensitized to chemical pollutants as well (it is called MSC: Multiple Chemical Sensitivity). [4]
Respiratory system The following table shows specific effects of every indoor chemical pollutant: [4, 8, 9, 10] The term “Sick Building Syndrome” (SBS) is also often mentioned while talking about indoor air quality. This term, first employed on the 1970s, describes a situation in which reported symptoms among a population of building occupants can be temporally associated with their presence in that building (typically but not always an office building). But not specific illness or cause can be identified. In contrast, the term “Building Related Illness” (BRI) is used when symptoms of diagnosable illness are identified and can be attributed directly to airborne building contaminants. A 1984 World Health Organization Committee report suggested that up to 30 percent of new and remodeled buildings worldwide may be the subject of excessive complaints related to indoor air quality (IAQ). Often this condition is temporary, but some buildings have long-term problems. [D, F] The symptoms of SBS include headaches; eye, nose or throat irritation; dry cough; dry or itchy skin; dizziness and nausea; difficulty in concentrating; fatigue; and sensitivity to odours. Besides, most of the complainants feel relief soon after leaving the building. Consequently, it is important to pay attention to the time and place the symptoms occur (short-term). If the symptoms fade or go away when a person is away from the home for example and return when the person returns, an effort should be made to identify air sources that may be possible causes. 2.5 COST OF INDOOR AIR POLLUTION Indoor air pollution has significant economic costs. The global cost of indoor air pollution can be divided into three parts: cost for premature deaths, medical cost (cancer treatments, hospitalizations, chronic respiratory disease and emergency room visits for asthma attacks and CO poisoning) and lost productivity cost (absenteeism, reduced worker productivity). In 2000, indoor air pollution from solid fuels was responsible was responsible for more than 1,6 millions annual deaths (i.e. one death every 20 seconds) and 2,7 % of the global burden of disease, according to the WHO. This makes the risk factor the second biggest environmental contributor to ill health, behind unsafe water and sanitation (indoor air pollution features at the 8th rank of the most important risk factors). The importance of indoor air pollution as a public health treat varies drastically according to the level of development: in high-mortality developing countries, indoor air pollution is responsible for up to 3,7 % of the burden disease, while the same risk factor no longer features among the top ten risk factors in industrialized countries. Besides, every year, indoor air pollution is responsible for nearly 800 000 deaths due to pneumonia among children under 5 years old. [G] For example in California, the premature death cost was estimated to 36 billions of dollars per year (for year 2000 dollars and year 2000 population), the medical cost was about 0,6 billions of dollars per year and the lost productivity cost was estimated to 8,5 billions of dollars per year. Consequently, it represented a total cost of 45 billions of dollars per year due to indoor air pollution. But because of the limited amount of information available for accurately estimating indoor pollution costs and the broad range of effects and resultant costs, there is considerable uncertainty in the cost estimates. [10]
Cost of bad indoor air in
3. INDOOR ENVIRONMENTS STUDIED 3.1 SPA PROJECT IN
The spa will be built in Christianshavn in The disinfection of the water is required because of the micro-organisms present that can make us ill. These micro-organisms come from the water itself and also from the swimmers: every swimmer adds 1.000.000 to 1.000.000.000 of micro-organisms when entering the pool. These pollutants result from saliva, excretion products, swimwear, skin tissue, sebum, sweat, hairs, cosmetics… In a spa pool there are more difficulties for disinfection than a swimming pool. Indeed, spa pools are much smaller, have a higher ratio of bathers to water volume and thus the amount of organic material is far higher than in swimming pool water. Furthermore, the temperature is in general higher in spa pools. That is why water disinfection is a key control measure. [11] The disinfectants used must meet certain demands: they should be harmless, non-irritating, active in small concentrations, remain their activity for a long time, active in the pool itself, easily to measure and safe to use. [H]
One of the first known uses of chlorine for water disinfection was by John Snow in 1850 in Hypochlorous acid is the active, killing form of chlorine. Depending on the pH value, hypochlorous acid partly expires to hypochlorite ions (OCl-). These molecules (HOCl and OCl-) are called “free chlorine molecules”; they are available for disinfecting. They kill microorganisms by slashing through the cell walls and destroying the inner enzymes, structures and processes. The microorganisms will either die or suffer from reproductive failure. However, when chlorine is added to water for disinfection purposes, it usually starts reacting with dissolved organic and inorganic compounds in the water. The products formed are called “active chlorine compounds”. For example, chlorine can react with ammonia (NH3) to form chloramines. After that, chlorine can no longer be used for disinfection. Consequently, the dose of chlorine to apply must be high enough for a significant amount of chlorine to remain in the water (after reaction with dissolved compounds). The chlorine enquiry is a function of the amount of organic matter in the water, the pH, the contact time and the exposure. Some researchers say that chlorine has some very serious health consequences when used as a sanitizer in swimming pools. Chlorine enters the body breathed in with contaminated air or when consumed with contaminated food or water. When small amounts of chlorine are breathed in during short time periods, it can affect the respiratory system. Chlorine can also cause skin and eye irritations. But in fact, it is not chlorine that is dangerous for the health but its by-products: chloramines and trihalomethanes (THMs). The chloramines are responsible for the smell and the irritant properties of the swimming-pool air. Thus, when swimmers complain of too much chlorine in the pool area, the real problem is too little free chlorine in the water (too much chlorine has been converted to chloramines). These chloramines, monochloramine (NH2Cl), dichloramine (NHCl2) and trichloramine (NCl3) are generated from the reaction of HOCl with ammonia and amino-compounds that originate from sweat and urine of the swimmers. [12, H] They are (especially NCl3) quite volatile and they partition easily from the water into the air. Some studies have identified trichloramine as the probable cause of respiratory problems and occupational asthma in swimmers and pool attendants, in indoor swimming pools. The trihalomethanes are also by-products of chlorination. They come from the substitution of the hydrogen atoms in methane (CH4) with the halogen atoms of chlorine or bromine. The methane is a natural product of our bodies and the products of this substitution called “THMs” are for example: CHCl3 (chloroform), CHBr3 (bromoform), CHCl2Br (bromodichloromethane) and CHClBr2 (dibromochloromethane). Chloroform can be measured in the blood or urine of regular swimmers. [11, H] Several health researches have been carried out in chlorinated swimming pools. In a Dutch research in 2001, swimming pool attendants were interviewed and a lot of employees suffered from forgetfulness, fatigue, chronic colds, voice problems, eye irritations, headache, sore throat, eczema and frontal sinus inflammation. Fertility problems were also mentioned. All problems were probably caused by working conditions: work during long hours in a warm and humid environment, and with exposure to chemical substances. Health problems vanish when swimming pool attendants do not work. Besides, in a French research undertaken by INRS, it has been shown that the first workers’ complaints appeared for a chloramine concentration of 0,5 mg/m3. All agents were complaining for a concentration of 0,7 mg/m3. [14] Epidemiological researches have shown that competitive swimmers have more bronchial hyperresponsiveness or asthma than other sportsmen. But the complaints disappear when they swim in outdoor swimming pools, because wind removes gasses from the air above the pool. [12] Besides, hypochloric acid with sunlight can cause the pH value to drop. And when it drops below 3,6 swimmers can suffer from dental abrasion: tooth enamel dissolves and the teeth become brittle and sensitive. [H] A survey with schoolchildren has taken place in As a consequence, it is necessary to control the formation of the chlorine by-products by having swimmers wash before entering, by treating the water, by maintaining adequate water exchange rates, and by constant dilution of the air above indoor swimming pools via good ventilation practises. Another alternative could be to use another disinfection technique.
Some of the alternatives that can be adapted to a spa are the following ones: ozonation, ultra-violet system, copper-silver ionization, salt water chlorination or a hydro physical dynamic flow water treatment.
Ozonation (with corona discharge): Ozone is produced where and when it is needed from oxygen-containing gases in ozone generators. A high voltage is applied between two concentrically arranged electrodes and some of the oxygen molecules in the input gas break down in the electric field. Then they immediately attach themselves to free oxygen molecules, forming ozone. Ozone reacts rapidly with organic matter, viruses, bacteria… and is converted back into oxygen dioxide. This treatment takes place in a technical room. A carbon bed is often used after that to avoid ozone residual to enter the pool. Indeed, in a lot of national legislations ozone residual is not allowed in the pool. As a disinfectant residual should remain in the pool (legislation), a chlorine or bromine dosage is added. Typically the treatment is made with 95% of ozone and 5% of chlorine. Ozone technology for swimming pools has been in regular use for over 50 years in Europe especially in Ultra-violet system: It is a physical treatment with UV radiation. The light necessary for UV disinfection is generated in special UV lamps. One of the most effective wavelengths and the most often used for disinfection is at 254 nm; it belongs to UV-C. This intensive UV light reaches the micro-organisms in the water and impacts directly on their DNA. By changing the DNA, the cell division of the micro-organism is interrupted: it can no longer reproduce itself and thus loses its pathogenic effect. [H, L, M] Copper-silver ionization: It is brought about by electrolysis. Electrodes are placed close together and the water flows past the electrodes. An electric current is created causing positively charged copper (Cu+ and Cu2+) and silver (Ag+) ions to form. The positively charged copper ions form electrostatic compounds with negatively charged cell walls of micro-organisms. The copper ions then penetrate the cell wall and as a result they will create an entrance for silver ions. These latter penetrate the core of the micro-organisms: they bond to various parts of the cell (DNA, RNA, cellular proteins and respiratory enzymes), causing life support systems into the cell to be immobilized. There is no more growth or cell division of the bacteria. The ions remain active until they are absorbed by a micro-organism. Globally, silver inhibits bacterial growth, rather slowly, and copper is an algaecide. [H, N] Salt water disinfection: With this method, chlorine is generated by electrolysis. The electrolysis is achieved by passing a mild saline solution through an electrolytic cell. First sodium chloride (NaCl à salt) is added to the pool water. The anode of the cell makes hypochlorous acid (HOCl) and hypochloric acid (HCl). The cathode of the cell makes sodium hydroxide (NaOH) and hydrogen gas (H2). Then these reactions take place: HOCl (anode) + NaOH (cathode) à NaOCl (sodium hypochlorite) that kills micro-organisms HCl (anode) + NaOH (cathode) à NaCl (salt) reused for the electrolysis The pool produces its own chlorine to sanitise itself. It is a closed loop system because the salt is used over and over again and only lost through splash out, carry out, backwashing and rainfall. [H, O] Hydro physical dynamic flow water treatment: This is a physical treatment. In a reactor chamber there is a cyclone process. The water is supplied by a high pressure pump to the reactor chamber. Consequently, very high flow and rotation velocities are created. The flow volume inside the reactor is diverted into several water layers. The vacuum centre cleaning (about -1,0 bar) permits to add natural oxygen mixture from the outside air directly to the reactor chamber process. The additional oxygen is dissolved in the water, forming free radicals, which act as an oxidation cold combustion cleaning grade process. [P] According to the advantages and disadvantages of each technique (See appendix 8), a comparative table has been drawn:
+ = advantage - = disadvantage ? = no data * = based on chlorine addition required (1) = possible formation of bromate (à more ventilation) (2) = technique that can destruct chloramines, thus it improves air quality (à less ventilation) (3) = nitric oxides and nitric acid can be formed which could lead to corrosion (according to some people) (4) = referring to price for one starter pack
In The local authorities are responsible for the agreement of a swimming pool and approve the disinfection technique used to treat the water. The disinfection technique has to meet certain demands according to the Danish legislation: levels of free chlorine, bounded chlorine and total chlorine; level of THMs; temperature and pH. Thus, the owner of the future pool has to make some experiences or some literature research and then make a report to the local authority to prove that the technique he wants to use will meet these demands and that the by-products will be removed or reduced to a level below the health effect limit. This could be a long and hard work especially for alternatives to chlorine because there are little references in Currently, the Danish EPA is working on trichloramines. They are making a risk assessment to know if trichloramines are responsible of asthma in swimming pools. They are also working on alternatives to chlorine through a literature research and it will be finished in a month. A year ago, they have made a risk assessment of THMs. The European Union does not take any position about disinfection treatments. There is not any legislation. There are some guidelines proposed by the WHO (pH, amount of bacteria… according to the different techniques) that can be used by the European countries to make their own legislation. European conferences about swimming pools also take place sometimes. The next conference will be next year and will be about the by-products and the chemicals. These conferences are in connection with the WHO. Authorities, companies and universities attend them. The objective of these conferences is not to make European standards, but just to share knowledge.
3.2 ANALYSIS IN A WORKPLACE ENVIRONMENT
The office room studied is situated in the Building Department in NIRAS, Allerød. It belongs to the new building first occupied in January 2005. The former use of the site was a parking area and a green area and before that there were fields. So normally, there is not industrial pollution. The room has a surface of 16,53 m2 and is occupied by one man. The office room includes: two windows, one door, two pieces of furniture (one small and one big) with shelves containing books, two desks, six chairs, one computer, one phone and two lamps. The ventilation of the room is a mechanical one and is called VAV (variable air volume) ventilation. The occupant chooses the temperature of the room and thus the volume of air entering the room is adjusted. The air entering the room is only fresh air (there is no recirculation of indoor air). The floor is covered with wood parquet and the walls are painted. Background information is collected to identify potential pollutants and to locate their sources and so to interpret the results of the analyses.
Two sampling were made in the room. First, an active sampling for aldehydes was carried out during 30 minutes. A chemosorption tube containing silica gel coated with 2,4-dinitro-phenylhydrazine under formation of hydrazone, and a pump calibrated to 214 mL/min were used for the sampling. The sampler was placed on the top of the shelves. Then, a passive sampling for VOCs was carried out during one week (including the week-end). An ATD tube (containing Chromosorb 106) was used for that purpose. The tube was hung on the black lamp on the desk. In fact, the samplers were placed in the breathing zone at 1-1,5m above the floor level in the centre area of the room, like it is recommended for an indoor air quality investigation. [16, 17] Normally, it is also advised to make sampling from outdoor air to have the background. It is really important in case of outdoor pollution (traffic road, industries…). In our case, it was not done because no outdoor pollution was suspected and because of limited budget. In addition, like in all indoor air quality investigations, a questionnaire was filled by the room’s occupant and a specific enquiry about furnishing and cleaning was carried out. (See appendices 11, 12 and 13)
The analyses were done by Eurofins Environment A/S. The analytical methods for aldehydes and VOCS were HPLC/UV and thermic desorption with GC/MS respectively. Aldehydes: Six aldehydes were analyzed by Eurofins: formaldehyde, acetaldehyde, propanal, butanal, pentanal and hexanal. The formaldehyde is the only quantified compound and is also the only compound for which the WHO proposed an air quality guideline of 100 µg/m3 for a 30 minutes’ period. [18] It is a threshold limit: above it, irritation of the upper respiratory ways can appear. For the other aldehydes, there are not air quality guidelines from the WHO. The only references that can be used are short-term and long-term exposure limits from the work legislation. First, the concentration of formaldehyde measured (39 µg/m3 for 30 min) is well above the WHO air quality guideline (100 µg/m3 for 30 min) and also above the values from the work legislation (See appendix 14). So, there is not significant pollution with formaldehyde. The other aldehydes are just qualified. Thus, it is not easy to compare their values with exposure limits. Besides, there are not any exposure limits for some aldehydes (butanal and hexanal). For the acetaldehyde, the propanal and the pentanal, the concentrations measured (< 90 µg/m3) during 30 minutes is below the VME value (value for 15 minutes of exposure) and the VLE value (value for an exposure of 8h/day and 5 days/week). This means that there is not significant pollution for these compounds. Now, the INERIS scale for aldehydes in indoor environments (See appendix 14) shows that there is low pollution or medium pollution in this office room depending on the aldehyde. But if we consider the sum of the six aldehydes, it will be medium pollution or even high pollution. It cannot be said precisely because of the non-quantification (non precise concentrations) of five aldehydes. But it is likely to be medium pollution. Finally, the main sources of these aldehydes in this room seem to be furniture and books.
Volatile Organic Compounds (VOCs): Five VOCs (the major ones) were identified by Eurofins (acetone, acetic acid, toluene, α-pinene and diisobutyl-phthalate) and four of them were quantified. The sum of the others and the TVOC were also given. There is a WHO air quality guideline only for the toluene. The concentration measured for the toluene during one week (10 µg/m3) is above this value (260 µg/m3) also specified for one week. The result is also well above the exposure limits from the work legislation. (See appendix 15) For the other pollutants, only the exposure limits from the work legislation can be used, especially the VME value. But there is not any data for the α-pinene. Besides it is quite difficult to make comments for the acetone since this pollutant is not quantified (>45 µg/m3). But knowing the concentrations of TVOC, its concentration can be supposed to be below the work exposure limits. The concentrations of acetic acid, the diisobutyl-phthalate and toluene are also well below the VME values for these compounds. The concentrations of toluene, α-pinene and diisobutyl-phthalate (and perhaps acetone) refer to low pollution according the INERIS scale established for VOCs in indoor environments; whereas the concentrations of acetic acid and the others VOCs refer to medium pollution. The concentration of TVOC which represent the global concentration of VOC in the office room features to a medium pollution. Thus, this office room does not seem to be very polluted by VOCs. Besides, it is important to note that it is a recent room, so the concentrations of pollutants are still at their nearly maximums. They will decrease slowly over the time. The main sources of VOCs in this room are likely to be the furniture (desks, chairs and cupboards), the computer and the paint. The minor sources could be the floor covering, the building material (gypsum board) and the cleaning products (soap and oil).
This recent office room does not seem to have important indoor air quality problems according to the results of the analyses. However, the INERIS scale suggests medium pollution for both the aldehydes and the VOCs. This scale suggests limit values well below than those from the work legislation because it takes into account the “cocktail” of air pollutants. So, in this room precaution should be taken avoiding additional sources of pollutants. But the results are all the same justified by the age of the building and the sources present (furniture, paint). Besides, it is quite difficult to interpret the results since there is not any legislation for indoor environments. In addition, all the values from the WHO or the work legislation are for one pollutant alone in an environment without taking into account the interactions between pollutants. But an indoor environment is a “cocktail” of chemical pollutants. Thus, the reference values are not really adapted to comment indoor concentrations but they are the only tools that we can use today.
4. SOLUTIONS FOR A GOOD INDOOR AIR QUALITY 4.1 SOURCE CONTROL It is usually the most effective and reliable way to improve indoor air quality because it keeps pollutants from entering and spreading throughout a building. It is also a more cost-efficient approach to protecting IAQ than increasing ventilation because increasing ventilation can increase energy costs. Source control avoids, removes or reduces the sources of indoor air pollutants by using materials, consumer products and appliances that emit little or no air pollution. It can be accomplished through source substitution, source removal and source modification. [10]
Another example is the use of low VOC-containing paints or no VOC-containing paints instead of using paints with VOC. Source substitution could also be the use of an electric stove instead of a gas stove that emits a lot of combustion products.
Source removal involves eliminating the source from the building. For example, it includes having people smoke outdoors, avoiding the use of carpets and removing building furnishing that release toxic gases.
Source modification is the reduction of the rate at which a pollutant is emitted into the indoor environment. It could involve a change in design, formulation or usage of a consumer product. For example to reduce formaldehyde emissions, appropriate coating or sealers can be used to cover the products that emit formaldehyde. [10]
Emission rate of formaldehyde emitted from individual parts; comparison of non treatment (upper bar) with treatment (=coating, lower bar) [20] 4.2 VENTILATION / DILUTION
Relationship between ventilation and indoor air pollutants Ventilation can be natural or mechanical. Natural ventilation is the passive air movement through open doors or windows, and unintentional air infiltration through the cracks and gaps of the building envelope. For its part, mechanical ventilation is the active movement of air through the building using fans to pull outdoor air in, mix and circulate the air, and exhaust the indoor air to the outdoors. There are two types of mechanical ventilation: mixing and displacement. Mixing ventilation mixes fresh air and existing room air to uniformly dilute pollutants. It is the most common type of mechanical ventilation. Displacement ventilation was developed by Scandinavian countries and provides energy-efficient cooling and improved ventilation of the building. [10] It introduces cool, fresh air at low velocity at floor level. The cool, fresh air warms and rises without mixing with the stale air, and pushes room pollutants upward to be exhausted to the atmosphere. [2] However, natural ventilation has limited effectiveness and reliability because it depends on building occupant to open routinely windows, on indoor-outdoor temperature differences and on sufficient wind speeds. Mechanical ventilation must be properly design, operate and maintain. Besides there is a balance between the energy cost of ventilation and the indoor air quality to take into account. Sometimes, low air exchange rates are used to save money. Ventilation is really important in new or renovated buildings: the ventilation rate has to be increased for the first few weeks of occupancy. This will dilute possible emissions from new polluting sources. 4.3 AIR TREATMENT
Another approach to improve indoor air quality could be the absorption of the pollutants by building materials. The moisture buffer capacity of hygroscopic materials is well known to be used to moderate relative humidity (RH) of indoor air as well as moisture content variations in building materials and furnishings. This can help to ensure healthier indoor environments by preventing many processes that are harmful such as growth of house dust mites, surface condensation and mould growth. In the same way, porous materials can also absorb chemical pollutants. [21]
Comparison of the absorption of formaldehyde (5 ppm) between wool and nylon Some wall and floor porous materials (including gypsum board) can also absorb pollutants (especially VOCs) through the processes of sorption and diffusion. They absorb them and release them over time, thereby regulating the room climate and hence indoor air quality. [22] Finally, pollutants can also be trapped and adsorbed by filters (activated carbon for example) via the physisorption mechanism.
There are no applications for the moment concerning indoor environments. However a European program with innovative building materials to deal with atmospheric pollution was carried out from 2002 to 2005. This program is called PICADA for Photo-catalytic Innovative Coverings Applications for Depollution Assessment. The building materials and the coverings contain titanium dioxide (TiO2). The first results in outdoor places were quite good: they showed a cleanup of NO2 about 20% in the most unfavourable cases and about 80% for the most favourable cases. [R] The process is the following one: first pollutants are absorbed onto the covering surface and come into contact with TiO2. Then TiO2 absorbs the energy of the photons of the UV radiance. As a consequence, TiO2 releases holes and electrons. Then free radicals are produced by reaction of the holes and electrons with H2O and O2. These highly extremely reactive radicals act on absorbed pollutant particles. The final products are stored into the matrix of the covering or lixiviated. In the future, scientists will study if these products could also be used as depolluting products in indoor environments.
The photo-catalytic process (cyclic)
Plant physiologists already knew that plants absorb carbon dioxide and release oxygen as part of the photosynthetic process. Now researchers have found that many common houseplants absorb benzene, formaldehyde and trichloroethylene as well. Some houseplants are better at removing formaldehyde from the air, while others do a better job on benzene. The rates at which the plants clean the air will vary depending on the size of the plant, the temperature and how polluted the air is, among other things. The first investigation for indoor air treatment by plants was in 1989 with the NASA. NASA has been researching methods of cleansing the atmosphere in future space stations to keep them fit for human habitation over extended periods of time. The scientists tested three common indoor air pollutants: benzene, trichloroethylene and formaldehyde. They studied 19 different plants for two years and 15 were considered to be capable of reducing the studied VOCs. (See appendices 16 and 17) In addition of the leaves of the plants, soil and roots were found to play an important role in removing airborne pollutants. The micro-organisms in the soil became more adept at using trace gases as a food source, as they were exposed to them for longer periods of time. Their effectiveness was increased when leaves covering the soil were removed. The NASA studies generated the recommendation to use 15 to 18 good-sized houseplants in 6 to 8-inch diameter containers to improve air quality in an average 1 800 square foot house. [23] Australian studies in 2005 also show that indoor plants can remove pollutants. They studied the capacity of benzene and n-hexane removal of three species: Kentia palm, Peace Lily and Janet Craig. The results show that the micro-organisms were the “rapid-removal agents” and from three to ten times the maximum permitted Australian occupational indoor air concentrations of each compound can be removed within 24 hours. [24] Mechanism of air treatment by plants Indoor plants have also been described as beneficial in working places since they can improve productivity (reducing absenteeism and staff turnover costs) and health and well-being of workers. 4.4 MY “
Considering all that was said before, an “ideal building” type can be drawn up. This building should provide the best possible indoor air quality. Thus, materials should be selected in that way. [4, 9, T, U, V] Building materials: traditional materials such as bricks, clay or cement (F breathable walls) Insulation: - natural cotton fibre insulation - cellulose insulation - wool insulation - pumice Wall covering: - paints and sealants with no or low VOCs - paper wall coverings - cotton wall coverings - natural fibres such as wool or wood - Hessian jute - natural cork wall tiles Flooring: - bamboo flooring - cork flooring - wood floors - natural linoleum called marmoleum - marbleized concrete - tile or natural stone floors for wet areas Furniture: - only furniture with environmental labels - natural bamboo furniture - wood furniture (avoiding pressed-wood products) - furniture with coating or sealer for those that release a lot of formaldehyde Heating: - high radiation heating system (in ceiling or floor) - wall heating systems Ventilation: - hybrid ventilation systems = two-mode systems using feature of both passive (natural ventilation) and mechanical systems at different times of the day or seasons - displacement ventilation Plants: - 2 plants for a room with a surface area of 20 m2 (adapted from NASA recommendations) - Bamboo palm - Janet Craig - English ivy … Additional information: - non-smoking area - maintenance and cleaning of all appliances periodically - ideal indoor air conditions: 40-60% of relative humidity and room temperature between 19 and 22°C - an air purifier can be used when the indoor air contains large amounts of pollutants and the sources cannot be eliminated (but caution some air purifier can emit ozone)
CONCLUSION This study was done in order to know more about the indoor air pollution by chemicals and thus to be able to offer to NIRAS’ customers the best competitive consultancy on guaranteeing acceptable indoor air quality. For this purpose, literature search and interviews were carried out. First the nature and the sources of chemical pollutants were identified. The main compounds found in indoor air include: CO, CO2, NO, NO2, O3, VOCs, aldehydes, SO2, pesticides and radon. Their sources can be classified in four categories: outdoor air, building equipment, human activities, and chemical and physical reactions inside the building. But this pollution is not often taken into account seriously. Whereas, its cost is huge and the health problems can be really serious, little people take interest in it. It is even more paradoxical than the indoor air pollution concern all of us since we spend about 90 % of our time inside. However, this trend tends to change nowadays. Scientific studies were carried out and have pointed the bad indoor air quality in homes and offices. Technical solutions for a better indoor air quality do exist. They just have to be part of the construction steps. They include mostly the choice of materials and the adequate ventilation. In a constructed building with bad indoor air quality, the solutions can be the source removal or the source substitution, and also the addition of indoor plants to remove pollutants from the air. Some other solutions will certainly be born in nearly future, now that the building and construction companies have taken interest in the indoor air quality. Besides, the cases studied in this report are of particular interest. In the spa project, the owner would like to avoid chlorine because of its by-products that can contaminate the air. So, this shows that the individual people now begin to be aware of the indoor air pollution. The solutions proposed to this person were alternatives to chlorination (that is to say source substitution). In the office room studied, it has to be noted the good choice of several building components. This is why no significant pollution was detected. It suggests that now in new building, indoor air quality is integrated in the construction scheme. However, the air quality of the room tested is not perfect, some points can be enhanced. It means that the indoor air quality is not controlled entirely yet. For example, furniture should be chosen according to well-known environmental labels, the paints should contain no VOC or very low levels of VOC and it is important to aerate during and after the cleaning to remove the most part of chemical from cleaning products. Finally, one of the main barriers for a good indoor air quality is likely to be the lack of legislation for the pollutants found in indoor environments. Very little pollutants have air quality guidelines proposed by the WHO. No international or national exist for indoor air pollution. The only tools that can be used to interpret concentrations measured in indoor environments are the exposure limits from the work legislation (values for short-term exposure and long-term exposure). But it is clear that they are not really adapted. In this legislation, the values proposed are for one chemical substance taken alone in an environment. They do not take into account the interactions between pollutants that can occur. And this often occurs in an indoor environment that is known as a “cocktail” of chemical pollutants. Thus, one of the future tasks to lead in indoor air quality would be the realization of international or national standards. Studies about health problems related to indoor air pollution are now quite numerous that political people can take the problem seriously. The mortality due to that pollution will certainly decrease because some people act positively for that (the “healthy building” is a new trend). But this decrease will not take place until several years and will not be very important if we do not more than what is done currently. Further researches have to be done to develop very ecological building components but also efficient air treatment. More information has to be given to the customers too. Political people should help researchers in that way.
REFERENCES [1] WHO (World Health Organization) – Classification, Assessments, Surveys and Terminology Team. International Classification of Functioning, Disability and Health. [2] State of knowledge report: Air Toxics and Indoor Air Quality in [3] LEVIN H. Indoor Air Pollutants – Part 1: General description of pollutants, levels and standards. AIVC (Air Infiltration and Ventilation Centre), Ventilation Information Paper, December 2003, n°2, 12 p. [4]. The Inside Story: A Guide to Indoor Air Quality. [5] CRUMP D. Nature and sources of indoor chemical contaminants. 10p. [6]. Indoor Pollutants. Committee on Indoor Pollutants, Board on Toxicology and Environmental Health Hazards, National Research Council, 1981. 552 p. [7] Clearing the Air: Asthma and Indoor Air exposures. [8] Indoor Air Pollution – An introduction for Health Professionals. [9] The Healthy Indoor Air Guide – The Chemistry of Housing. 2nd edition. [10] Indoor Air Pollution in [11] Management of spa pools: controlling the risk of infection. [12] Health issues: chlorinated swimming pools. Healthy Building International (HBI), Inc. 6p. [13] NEMERY B., HOET P.H.M., NOWAK D. Indoor swimming pools, water chlorination and respiratory health (editorial). European Respiratory Journal. ISSN 0903-1936. 4 p. [14] INRS (Institut National de Recherche et de Sécurité). Troubles d’irritation respiratoire chez les travailleurs des piscines. DMT (Documents pour le Médecin du Travail) études et enquêtes, 1er trimestre 2005, n°101, 22 p. [15] Alternatives disinfectants and oxidants – EPA Guidance Manual. [16] Report No 14: Sampling strategy for volatile organic compounds (VOCs) in indoor air. European Collaborative Action (ECA) – Indoor Air Quality and its impact on man, 1994. 48p. Report EUR 16051 EN. [17] Indoor Air Quality in Office Buildings: a technical guide. [18] Air Quality Guidelines for [19] Report No 24: Harmonisation of indoor material emissions labelling systems in the EU – Inventory of existing schemes. European Collaborative Action (ECA) – Urban air, Indoor environment and Human exposure, 2005. 50p. Report EUR 21891 EN. [20] HORI M., OHKAWARA T., HANDA S. and WAKUI T. Improvement of IAQ by coating of adsorptive polymer: the development of material, evaluation and its application. [21] MORTENSEN H.L., RODE C. and PEUHKURI R. Full scale tests of moisture buffer capacity of wall materials. Lyngby (DK): [22] STRAUBE J.F. and ACAHRYA V. Indoor Air Quality, Healthy Buildings, and Breathable Walls. [23] WOLVERTON B.C, JOHNSON A. and BOUNDS K. Interior landscape plants for indoor air pollution abatement. [24] WOOD R. Improving the indoor environment for health, well-being and productivity. Interviews: [25] Linda Bagge from the Danish EPA (Environmental Protection Agency). 26/07/06 Swimming pools in Websites: [A] [B] Observatoire de la Qualité de l’Air Intérieur [C] American Lung Association [D] [E] HEDON Household Energy Network http://www.hedon.info/goto.php/WhatCausesIndoorAirProblems [F] WIKIPEDIA, The Free Encyclopedia http://en.wikipedia.org/wiki/Sick_building_syndrome [G] WHO http://www.who.int/indoorair/health_impacts [H] Lenntech http://www.lenntech.com/home.htm [I] Poolcenter [J] Ozone Tech Systems [K] WEDECO AG [L] WEDECO UV Systems [M] STRANCO Leisure Products http://www.stranco-leisure.co.uk [N] [O] Jandy Pool Products [P] Nielsen Technical Trading ApS [Q] ThermafleeceTM [R] PICADA project [S] Plant’airpur [T] Healthy Building Network http://www.healthybuilding.net [U] Building for http://www.buildingforhealth.com [V] http://www.greenbuildingsupply.com
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