Detrital sedimentary rocks are described effectively in terms of compositional, textural, and structural attributes. In the procedure presented, rock-framework types, grain-boundary contacts, cement composition, and bedding characteristics are recorded. Standardized visual comparison charts aid in determining roundness, colour, and percentage distributions of particle composition and size. Quantified descriptions are more useful than field names in comparing stratigraphic sections, analyzing sedimentary parameters, and adapting observations to classifications.
Particle size is the primary basis for distinguishing among various detrital sedimentary rocks. (Breccia photo by E. J. Tarbuck; all other photos by Dennis Tasa) Engineering geology Glaeser, J. Douglas. “PROCEDURE FOR DESCRIPTION OF DETRITAL SEDIMENTARY ROCKS.” Proceedings of the Pennsylvania Academy of Science, vol. 36, 1962, pp. 213–217. JSTOR, www.jstor.org/stable/44112152. Accessed 8 Jan. 2020.
Beam bridge is the one which comes to your mind when someone asks you about what is a bridge? This is one of the basic type of bridges.
This type of bridges are simply supported bridges consisting of horizontal beams and vertical piers; Beam bridges are also named as stringer bridge or girder bridge. These type of bridges are typically spanned with two or more spans and supported by abutment or pier at each end. This type of bridges are constructed using RCC, Wood, steel etc. Beam bridges have span less than 80m.
As mentioned above, beam bridges are simply supported bridges (beam that is supported on piers), where the beam is laid across the supports. In this type of bridges, the beam should be strong enough to bear the loads on it. These loads are further carried to bridge supports and then to earth.
The top edge of the beam possesses compression as the loads are applied on it where the lower part of the beam is being stretched and is under tension.
Advantages of Beam bridge:
1.This type of beams are very easy to construct and erect. 2. This type of beams are good for short spans. 3. Wide distances can be spanned by resting beams on piers. 4. Ease in constructing temporary bridges.
Disadvantages of Beam bridge:
1. Can be expensive, requires RCC to built. 2. They are spanned by limits.
Arch bridge:
An arch bridge is the most popular type of bridge which is extensively used by ancient Romans.The arch bridge is usually made up of stone, concrete or steel. As the name itself mirroring that, the bridge is in the shape of an arch. An arch bridge is a curve shaped bridge where the load on the curve is not directly applied straight down, but instead, loads are carried along the curve of the arch to the end of supports. Meaning that no part of the bridge takes a high amount of pressure. These supports are also called as abutments. Abutments carry loads of the entire bridge & it is responsible for holding the arch in a precise position.
The no. of curves (arches) in a bridge depends on stress and loads that bridge should support. The span length of arch bridges is normally up to 250m, and the roadway of the bridge lies on the arch structure.
Advantages of Arch Bridge:
1. Easy to build with the locally available material.
2. these type of bridges are very rigid and extremely strong.
3. Arch bridges are built up with a variety of materials like stone, concrete, steel, etc.
Disadvantages of Arch bridge:
1. They take a long time to build.
2. It requires a massive amount of building materials to build.
Truss Bridge:
Truss is a framework consisting of struts (inclined members). These bridges are constructed by using trusses which are comprised of many small elements forming triangular trusses. The span length of truss bridge is in between 50m-110m.
Trusses are very rigid, lightweight and can support heavy loads. Trusses serve in transferring the load from a single point to the wider area. The weight of the bridge is very less when compared with other types.
When the load is applied to the truss bridge, the top edge possess compression and loads are shared among the angled members to supports and then to earth.
Advantages of Truss Bridge:
1. This type of bridge is easily built in the factory and then framed on site. 2. The piers or supports are comparatively less when compared to the beam bridge, 3. They are strong and rigid and very light on weight possess efficient use of materials.
Disadvantages of Truss Bridges:
1. Requires high skilled professionals to design it. 2. They are more complex than beam bridges in terms of designing.
Suspension bridges:
This type of bridges are constructed by suspending the deck slab using suspension cables. The roadway is hanged using steel cables which are connected to two towers and secured by anchors on both ends of the bridge.
In addition to the deck slab, the truss system is also featured with truss system just beneath the deck which helps to stiffen and to keeps the deck in precise position to reduce the tendency of the roadway to sway.
When the load is applied to the suspension bridge, the deck slab possess compression and then travels up the ropes, cables or chains to transfer the compression to the towers. The towers then dissipate the compression directly into the earth by anchors.
The supporting cables which run parallel to the bridge possess tension forces, and these are connected to anchorages. Bridge anchorages are massive concrete blocks which serve in dissipating the tension force to the ground
Bridge anchorages are essentially solid rock or massive concrete blocks in which the bridge is grounded. Tensional force passes to the anchorages and into the ground. The span length of Suspension bridge is in between 150m-2000m
Advantages of Suspension bridge:
1. Strong and lightweight. 2. These type of bridges provide long span which helps in crossing the river.
Disadvantages of Suspension bridge:
1. Expensive to build. 2. Prone to sway and ripple with the wind, so this type of bridges are not suitable for railways.
Cable-stayed bridge:
This type of the bridge are modern bridges and it is similar to the suspension bridge. In this type, cables are connected directly to the tower instead of suspended cables. Tension is constantly acting on the cables, which are stretched because they are attached to the roadway. This type of bridge doesn’t have any anchorages to bear the compression and has only one tower to carry the compression. The span length of Cable stayed bridge is in between 500m-1000m.
In this type of bridge, the cables are directly connected to the roadway at different points radially, and towers alone bear the compression forces.
Advantages of Cable-Stayed Bridge:
1. It is more economical when compared with the suspension bridge. 2. It is good for medium spans and can be easily built by cantilevering out from the tower.
Disadvantages of Cable-Stayed Bridge:
1. Maintenance and inspection may be more difficult. 2. this type of bridges are not suitable for far distances.
Cantilever bridge:
The word cantilever refers that the beam which has only one support and the other end is kept free in space. Cantilever bridges are same to this but don’t think that one end of the bridge is kept free. Cantilever bridges are constructed in parts and the two free ends are connected with suspended deck. Cantilever bridge has a span in between 150m-500m.
Any bridge is subjected to compression and tension forces. In this type of bridge, the suspended deck is provided to join the two free ends of the cantilever bridge.
When the load is applied on cantilever bridge, the top supports are subjected to a tensional force (pulling force), and bottom supports are subjected to the compression force( pushing force) which makes the bridge to be balanced. As long as force is balanced, the bridge will stand in stable position.
Advantages of Cantilever Bridge:
1. This type of bridges are adopted only when the supports cannot be provided at specific positions. 2. Support is required only on one side of the cantilever.
Disadvantages of Cantilever Bridge:
1. Cantilever bridges are prone to high turning stress during construction. 2. If the forces aren’t balanced the bridge may buckle.
A 500 metre road from Ratmalana to Borupana, South of Colombo had been paved with an asphalt mixture containing shredded and molten plastic extracted from municipal waste.
Non-recyclable plastic waste is taken from municipal waste (in Sri Lanka plastic, paper and food waste is now separated in households) shredded and heated with aggregates at 165 degrees centigrade.
"The molten waste-plastic-mix coats the heated aggregates before being coated with bitumen," the firm said.
"The new material – waste plastic modified asphalt concrete mix – will be applied for surfacing of roads under 150 degrees centigrate temperature. "
The plastic asphalt mixture not only solves the waste problem but cuts road construction costs and makes the pavements more durable.
Tests are conducted on the pilot project, the company said.
"Similar waste plastic modified asphalt mixes are successfully applied to road surfacing in countries such as UK, Canada, Netherlands, Philippines, India and Indonesia,"
The Plastic and Bitumen Mixture
Using recycled plastic for road building sounds simple, but it actually requires a complex process to create the right material. "Different plastics do different things to bitumen," he explains. "If you use the wrong mix, it actually can make the bitumen more brittle."
It is good to avoids using PET bottles and other types of plastic that are easily recycled, and instead concentrates on types of waste plastic that might otherwise end up buried in the ground. Reid declined to go into too much detail, so as not to reveal too much about MacRebur's proprietary process.
In addition to keeping plastic out of landfills, the company's plastic road materials can save about 1 ton (.907 metric tons) in carbon dioxide output for each ton of bitumen that the plastic replaces, according to this fact sheet from MacRebur's website.
சேகரிக்கப்பட்ட பிளாஸ்டிக் கழிவுகள், 1.60 மி.மீ. முதல் 2.50 மி.மீ. அளவுள்ள சிறு சிறு துகள்களாக வெட்டு இயந்திரங்களின் உதவியால் வெட்டப்பட்டு, சேகரித்து வைக்கப்படுகிறது. பின்பு இவை, தார்ச்சாலை அமைக்க சேகரிக்கப்பட்ட 110° செல்சியஸ் அளவிற்கு சூடுபடுத்தப்பட்ட கற்களுடன் சேர்த்து சுழற்சி முறையில் கலக்கப்படுகிறது. அவ்வாறு கலக்கப்படும் போது, கற்களில் உள்ள 1709 செல்சியஸ் வெப்பத்தினால், 30லிருந்து 60 வினாடிகளுக்குள் சிறு துகள்களாக நறுக்கப்பட்ட, பிளாஸ்டிக் துகள்கள் இளகி, கற்களின் மேல் போர்த்தியது போல், கற்களின் மேற்பரப்புகளை முழுவதுமாக மூடிவிடுகிறது.
இவ்வாறு இளகிய பிளாஸ்டிக் கழிவுகளுடன் சேர்க்கப்பட்ட கற்கள், உறுதியானவையாகவும், பிடிப்புத் தன்மையுள்ளதாகவும், மாறிவிடுகிறது. மேலும், கற்களின் மேற்பரப்பில் உள்ள சிறு சிறு நுண் இடைவெளி முழுவதுமாக மூடப்படுவதால், அதனுள், மழைநீர் அல்லது உப்பு கலந்த நீர் புகாமல் தடுக்கப்படுகிறது. இதனால், கற்கள் மழைநீரை உறிஞ்சி சிறு சிறு கற்களாக உடைவது தவிர்க்கப்படுவதுடன், சாலை குறுகிய காலத்திற்குள் பாழ்படுவது தவிர்க்கப்படுகிறது. இவ்வாறு, இளகிய பிளாஸ்டிக் கழிவுகளுடன் சேர்க்கப்பட்ட கற்களுடன், 1650 செல்சியஸ் வெப்ப அளவில் சூடுபடுத்தப்பட்ட தார் சேர்க்கப்படுகிறது.
மேலே கூறப்பட்ட வெப்ப அளவுகளில், தயார் செய்யப்பட்ட கலவையானது, 1109 - 1209 செல்சியஸ் வெப்ப அளவிற்குள்ளாக, தயார் நிலையில் உள்ள சாலைகளில் பரப்பப்பட்டு, கனமுள்ள சாலை உருளை வண்டி மூலம் இறுக்கம் கொடுக்கப்பட்டு, பிளாஸ்டிக் தார்ச் சாலை அமைக்கப்படுகிறது. 10 சதுர மீட்டர் அளவும் 25 மி.மீட்டர் கனமும் உள்ள பிளாஸ்டிக் தார்ச்சாலை அமைக்க, 27 கிலோ தார்க்கலவையும் 3 கிலோ பிளாஸ்டிக் நறுக்குகளும் தேவைப்படும். சாதாரண தார்ச் சாலை அமைக்க 30 கிலோ தார்க்கலவை தேவைப்படும். ஒரு பிளாஸ்டிக் சாலை அமைக்க தார்க்கலவையின் அளவில் 10 சதவீதம் பிளாஸ்டிக் நறுக்குகள் தேவைப்படும். இவ்வாறு அமைக்கப்பட்ட சாலைகள், உறுதி வாய்ந்தவையாகவும் மழைக்காலங்களில் சேதமடையாமலும் பிளாஸ்டிக் கழிவுகளின் பயன்பாட்டினால் புற ஊதா நிறக் கதிர் வெளிப்பாடு இல்லாமலும், அதிக கனரக வாகனப் போக்குவரத்தை தாங்கக் கூடியவையாகவும், குறைந்தது 7 வருடங்களுக்கு எந்தவித சேதாரம் இல்லாமலும் பயன்பாட்டில் இருக்கும்.
Alternative Method
தற்போது பல்கலைகழகங்களில், கழிவு பிளாஸ்டிக் பொருட்களைக்கொண்டு வீதி அமைத்தல் எனும் விடயத்தின் கீழ் (Using Waste Plastic in Road Construction) எனும் தலைப்பின் கீழ் பல ஆய்வுக்கட்டுரைகள் வெளி வந்துள்ளன. இதில் பாவிக்கப்படும் தாருக்கு சிபாரிசு செய்யப்பட்டளவு பிளாஸ்டிக் சேர்க்கப்பட்டு தார் வீதிகளுக்கு பாவிக்கலாம் என கூறப்பட்டுள்ளது. இதனடிப்படையிலேயே எனிவரும் காலங்களில் கார்பட் வீதிகளுக்கு போடப்படும் அஸ்போல்ட் கொங்கிறீட்டுடன் சிபாரிசு செய்யப்பட்ட அளவு பிளாஸ்டிக் சேர்க்கப்பட்டு கார்பட் வீதிகள் அமைக்கப்படவுள்ளது.
இவ்வாறு பிளாஸ்டிக் சேர்ப்பதனால் வீதியின் பாவனைக்காலம் கூடுதலாகவும் வீதிகள் உறுதியாகவும் இருக்கும் எனவும் கூறப்படுகின்றது அத்துடன் மிக முக்கியமான விடயம் நகரிலே சேகரிக்கப்படும் பிளாஸ்டிக் போத்தல்கள் மீள் பாவனைக்கு உட்படுத்தி சுற்றுச்சூழலை பாதுகாக்கவும் முடியும்.
திருகோணமலை நகராட்சிமன்றம் பரீட்சாத்தமாக இராஜவரோதயம் சதுக்கத்திலுள்ள சிறிய வீதியொன்றிற்கு துண்டுகளாக வெட்டப்பட்ட பிளாஸ்டிக் போத்தல்களை தாருடன் உருக்கி 12.03.2021 அன்று வீதி தாரிடும் வேலையை ஆரம்பித்தது. தாரினையும் பிளாஸ்டிக்கினையும் உருக்கிய கலவையைக்கொண்டு சிறப்பாக வீதியை அமைத்துக்கொண்டது.
Indoor air quality (IAQ) in I-BEAM refers to the quality of the air inside buildings as represented by concentrations of pollutants and thermal (temperature and relative humidity) conditions that affect the health, comfort and performance of occupants. Other factors affecting occupants, such as light and noise, are essential indoor environmental quality considerations but are not treated in I-BEAM as core elements of indoor air quality.
Why is IAQ Important to Building Managers?
Buildings exist to protect people from the elements and to otherwise support human activity. Buildings should not make people sick, cause them discomfort, or otherwise inhibit their ability to perform. How effectively building functions to support its occupants and how efficiently the building operates to keep costs manageable is a measure of the building's performance.
The growing proliferation of chemical pollutants in consumer and commercial products, the tendency toward tighter building envelopes and reduced ventilation to save energy, and pressures to defer maintenance and other building services to reduce costs have fostered indoor air quality problems in many buildings. Occupant complaints of odours, stale and stuffy air and symptoms of illness or discomfort breed undesirable conflicts between occupants or tenants and building managers. Lawsuits sometimes follow.
If indoor air quality is not well managed daily, remediation of ensuing problems and/or resolution in court can be extremely costly. So it helps to understand the causes and consequences of indoor air quality and to manage your building to avoid these problems.
Occupant Symptoms Associated with Poor Indoor Air Quality
Human responses to pollutants, climatic factors and other stressors such as noise and light are generally categorised according to the type and degree of reactions and the time frame in which they occur. Building managers should be usually familiar with these categories, leaving detailed knowledge to health and safety professionals.
Acute Effects: Acute effects are those that occur immediately (e.g., within 24 hours) after exposure. Chemicals released from building materials may cause headaches, or mould spores may result in itchy eyes and runny noses in sensitive individuals shortly after exposure. Generally, these effects are not long-lasting and disappear soon after exposure ends. However, exposure to some bio-contaminants (fungi, bacteria and viruses) resulting from moisture problems, poor maintenance or inadequate ventilation has been known to cause serious, sometimes life-threatening respiratory diseases which themselves can lead to chronic respiratory conditions.
Chronic Effects: Chronic effects are long-lasting responses to long term or frequently repeated exposures. Long term exposures to even low concentrations of some chemicals may induce chronic effects. Cancer is the most commonly associated long term health consequence of exposure to indoor air contaminants. For example, long term exposure to the following increases cancer risk:
environmental tobacco smoke
radon
asbestos
benzene
Discomfort: Discomfort is typically associated with climatic conditions, but building contaminants may also be implicated. People complain of being too hot or too cold or experience eye, nose or throat irritation because of low humidity. However, reported symptoms can be challenging to interpret. Complaints that the air is "too dry" may result from irritation from particles on the mucous membranes rather than low humidity, or "stuffy air" may mean that the temperature is too warm or there is lack of air movement, or "stale air" may mean that there is a mild but difficult to identify odour. These conditions may be unpleasant and cause discomfort among occupants, but there is usually no serious health implication involved. Absenteeism, work performance and employee morale, however, can be seriously affected when building managers fail to resolve these complaints.
Performance Effects: Significant measurable changes in people's ability to concentrate or perform mental or physical tasks have been shown to result from modest changes in temperature and relative humidity. Besides, recent studies suggest that similar effects are associated with indoor pollution due to lack of ventilation or the presence of pollution sources. Estimates of performance losses from poor indoor air quality for all buildings suggest a 2-4% loss on average. Future research should further document and quantify these effects.
Building Associated Illnesses
The rapid emergence of indoor air quality problems and
associated occupant complaints have led to terms which describe illnesses or
Effects particularly associated buildings. These include:
Sick Building Syndrome
Building-Related Illness
Multiple Chemical Sensitivity
Sick Building Syndrome (SBS): Sick Building Syndrome (SBS)
is a catch-all term that refers to a series of acute complaints for which there
is no apparent cause and where medical tests reveal no particular abnormalities.
The symptoms display when individuals are in the building but disappear when
they leave.
Complaints may include such symptoms as:
irritation of the eyes, nose and throat
headache
stuffy nose
mental fatigue
lethargy
skin irritation
These complaints are often accompanied by non-specific
Complaints such as the air are stuffy or stale. A single causative agent (e.g.,
contaminant) is seldom identified, and charges may be resolved when building
operational problems and/or occupant activities identified by investigators are
Corrected. Experience in resolving SBS complaints has led to many of the
suggestions for "good practice" found in I-BEAM.
The likely outcomes
of SBS problems which are not quickly resolved to include:
increased absenteeism
reduced work efficiency
deteriorating employee morale
Building-Related Illness (BRI): Building related illness
refers to a defined disease with a known causative agent resulting from
Exposure to the building air. While the causative agent can be chemical (e.g.,
Formaldehyde), it is often biological. Typical sources of organic
contaminants are:
humidification systems
cooling towers
drain pans or filters
other wet surfaces
water damaged building material
Symptoms may be specific or mimic symptoms commonly
Associated with the flu, including fever, chills and cough. Serious lung and
Respiratory conditions can occur. Common examples of building-related illness
include:
Legionnaires' disease
hypersensitivity pneumonitis
humidifier fever
Multiple Chemical Sensitivity (MCS): It is generally
recognised that some persons can be sensitive to particular agents at levels
Which do not have a noticeable effect in the general population? Besides,
it is recognized that certain chemicals can be sensitisers in that exposure to
the compound at high levels can result in sensitivity to that chemical at much
lower levels.
Some evidence suggests that a subset of the population may
be especially sensitive to low levels of a broad range of chemicals at levels
typical in today's home and working environments. This apparent condition has
come to be known as multiple chemical sensitivity (MCS).
Persons reported having MCS apparently have difficulty
being in most buildings. There is significant professional disagreement
concerning whether MCS actually exists and what the underlying mechanism might
be. Building managers may encounter occupants who have been diagnosed with MCS.
Resolution of complaints in such circumstances may or may not be possible with
the guidance provided in I-BEAM. Responsibility to accommodate such individuals
is subject to negotiation and may involve arrangements to work at home or in a
different location.
Building Factors Affecting Indoor Air Quality
Factors Affecting Indoor Climate
The thermal environment (temperature, relative humidity and
airflow) are essential dimensions of indoor air quality for several reasons.
Many complaints of poor indoor air may be resolved by simply
altering the temperature or relative humidity
Thermally uncomfortable people will have a lower
tolerance to other building discomforts.
The rate at which chemicals are released from building
materials are usually higher at higher building temperatures.
Thus, if occupants are too warm, it is also likely that they
are being exposed to higher pollutant levels.
Indoor thermal conditions are controlled by the heating,
Ventilating, and air conditioning (HVAC) system. How well the thermal
the environment is managed depends on the design and operating parameters of The system, and on the heat gains and losses in the space being controlled. These
gains and losses are principally determined by:
indoor sources of heat
the heat gains from sunlight
the heat exchange through the thermal envelope
the outdoor conditions and outdoor air ventilation rate
Factors Affecting Indoor Air Pollution
Much of the building fabric, its furnishings and equipment,
Its occupants and their activities produce pollution. In a well functioning
the building, some of these pollutants will be directly exhausted to the outdoors
and some will be removed as outdoor air enters the building and replaces the
Air inside. The air outside may also contain contaminants which will be brought
Inside in this process. This air exchange is brought about by the mechanical
introduction of outdoor air (outdoor air ventilation rate), the automatic
the exhaust of indoor air and the air exchanged through the building envelope
(infiltration and exfiltration).
Pollutants inside can travel through the building as air
flows from areas of higher atmospheric pressure to regions of lower atmospheric
pressure. Some of these pathways are planned and deliberate to draw
pollutants away from occupants, but problems arise when unintended flows bring
contaminants into occupied areas. Besides, some pollutants may be removed
from the air through natural processes, as with the adsorption of chemicals by
surfaces or the settling of particles onto surfaces. Removal processes may also
be deliberately incorporated into the building systems. Air filtration devices,
for example, are commonly incorporated into building ventilation systems.
Thus, the factors most important to understanding indoor
pollution are:
indoor sources of pollution,
outdoor sources of pollution,
ventilation parameters,
airflow patterns and pressure relationships, and
air filtration systems.
Types of Pollutants
Common pollutants or pollutant classes of concern in commercial buildings along with conventional sources of these pollutants are provided below.
Table 1.1 Indoor Pollutants and Potential Sources
Pollutant or Pollutant Class
Potential Sources
Environmental Tobacco Smoke
Lighted cigarettes, cigars and pipes
Combustion Contaminants
Furnaces, generators, gas or kerosene space heaters, tobacco products, outdoor air and vehicles
Biological Contaminants
Wet or damp materials, cooling towers, humidifiers, cooling coils or drain pans, damp duct insulation or filters, condensation, re-entrained sanitary exhausts, bird droppings, cockroaches or rodents, dust mites on upholstered furniture or carpeting, or body odours.
Particleboard, plywood, cabinetry, furniture and fabrics
Soil gases (radon, sewer gas, VOCs, methane)
Soil and rock (radon), sewer drain leak, dry drain traps, leaking underground storage tanks, and landfills
Pesticides
Termiticides, insecticides, rodenticides, fungicides, disinfectants and herbicides
Particles and Fibers
Printing, paper handling, smoking and other combustion, outdoor sources, deterioration of materials, construction/renovation, vacuuming, and insulation
Contaminant Sources
Indoor Sources
Identified below are some sources of contaminants commonly found in office buildings and offers some measures for maintaining control of these contaminants. Follow these measures to help maintain a healthy indoor environment.
Category/Common Sources
Housekeeping and Maintenance (Includes) -
cleansers
waxes and polishes
disinfectants
air fresheners
adhesives
janitor's/storage closets
wet mops
drain cleaners
vacuuming
paints and coatings
solvents
pesticides
lubricants
Tips for Mitigation and Control
Use low-emitting products
Avoid aerosols and sprays.
Dilute to proper strength (manufacturer's instructions)
Do not overuse; use during unoccupied hours.
Use proper protocol when diluting and mixing.
Store properly with containers closed and lid tight
Use exhaust ventilation for storage spaces (eliminate return air)
Clean mops: store mop top-up to dry
Avoid “air fresheners”—clean and exhaust instead.
Use high-efficiency vacuum bags/filters
Use Integrated Pest Management
Occupant-Related Sources (Includes)
Tobacco products
Office equipment (e.g., Printers and copiers)
cooking/microwave
art supplies
marking pens
paper products
personal products (e.g., perfume)
tracked in dirt/pollen
Tips for Mitigation and Control
Smoking policy
Use exhaust ventilation with pressure control for primary local sources.
Low emitting art supplies/marking pens
Avoid paper clutter
Education material for occupants and staff
Building Uses as Major Sources (Includes)
print/photocopy shop
dry cleaning
science laboratory
medical office
hair/nail salon
cafeteria
pet store
Tips for Mitigation and Control
Use exhaust ventilation and pressure control
Use exhaust hoods where appropriate; check hood airflows.
Building-Related Sources (Includes)
plywood/compressed wood
construction adhesives
asbestos products
insulation
wall/ floor coverings (vinyl/plastic)
carpets/carpet adhesives
wet building products
transformers
upholstered furniture
renovation/remodeling
Tips for Mitigation and Control
Use low emitting products.
Air out in the open/ventilated area before installing
Increase ventilation rates during and after installing
Keep material dry before enclosing.
Use renovation guidelines
HVAC system (Includes)
contaminated filters
contaminated duct lining
dirty drain pans
humidifiers
lubricants
refrigerants
mechanical room
maintenance activities
combustion appliances (e.g., boilers/furnaces, DHW, generators and stoves)
Tips for Mitigation and Control
Perform HVAC preventive maintenance
Use filter change protocol.
Clean drain pans; proper slope and drainage
Use potable water for steam humidification.
Keep duct lining dry; move to line outside of duct if possible.
Fix leaks/clean spills (see filter change protocol)
Maintain spotless mechanical room (not a storage area)
Avoid back drafting
Check/maintain flues from the boiler to outside
Keep combustion appliances properly tuned.
Disallow unvented combustion appliances
Perform polluting activities during unoccupied hours
Moisture (Includes)
mould
Tips for Mitigation and Control
Keep building dry
Mould and Moisture Control Protocol
Vehicles (Includes)
Underground/attached garage
Tips for Mitigation and Control
Use exhaust ventilation
Maintain garage under negative pressure relative to the building
Check airflow patterns frequently
Monitor CO
Outdoor Sources
Identified below are familiar sources of contaminants that are introduced from outside buildings. These contaminants frequently find their way inside through the building shell, openings, or other pathways to the inside.
Ambient Outdoor Air (Includes)
air quality in the general area
Tips for Mitigation and Control
Filtration or air cleaning of the intake air
Vehicular Sources (Includes)
local vehicular traffic
vehicle idling areas
loading dock
Tips for Mitigation and Control
Locate air intake away from the source
Require engines shut off at loading dock
Pressurise building/zone
Add vestibules/sealed doors near the source.
Commercial/Manufacturing Sources (Includes)
laundry or dry cleaning
restaurant
photo-processing
automotive shop/gas station
paint shop
electronics manufacturer/assembly
various industrial operations
Tips for Mitigation and Control
Locate air intake away from the source
Pressurise building relative to outdoors
Consider air cleaning options for outdoor air intake.
Use landscaping to block or redirect the flow of contaminants, but not too close to air intakes.
Utilities/Public Works (Includes)
utility power plant
incinerator
water treatment plant
Tips for Mitigation and Control
Locate air intake away from the source
Pressurise building relative to outdoors
Consider air cleaning options for outdoor air intake.
Use landscaping to block or redirect the flow of contaminants, but not too close to air intakes.
Agricultural (Includes)
pesticide spraying
processing or packing plants
ponds
Tips for Mitigation and Control
Locate air intake away from the source
Pressurise building relative to outdoors
Consider air cleaning options for outdoor air intake.
Use landscaping to block or redirect the flow of contaminants, but not too close to air intakes.
Construction/Demolition Tips for Mitigation and Control
Pressurise building
Use walk-off mats
Building Exhaust (Includes)
bathrooms exhaust
restaurant exhaust
air handler relief vent
exhaust from the major tenant (e.g., dry cleaner)
Tips for Mitigation and Control
Separate exhaust or relief from the air intake
Pressurise building
Water Sources (Includes)
pools of water on the roof and cooling tower mist
Tips for Mitigation and Control
Proper roof drainage
Separate air intake from the source of water
Treat and maintain cooling tower water.
Birds and Rodents (Includes)
faecal contaminants and bird nesting
Tips for Mitigation and Control
Bird proof intake grills
Consider vertical grills
Use Integrated Pest Management
Building Operations and Maintenance (Includes)
trash and refuse area
chemical/fertilisers/grounds keeping storage
painting/roofing/sanding
Tips for Mitigation and Control
Separate source from the air intake
Keep source area clean/lids on tight.
Isolate storage area from occupied areas
Ground Sources (Includes)
soil gas
sewer gas
underground fuel storage tanks
Tips for Mitigation and Control
Depressurise soil
Seal foundation and penetrations to foundation
Keep air ducts away from ground sources.
Protocols for Managing Major Sources of Pollution in Buildings
Type of Protocol
Solution
Remodelling and Renovation
Use effective strategies for material selection and installation.
Isolate construction activity from occupants.
Painting
Establish a protocol for painting and ensure that the contract is followed by both in-house personnel and by contractors.
Use low VOC emission, fast-drying paints where feasible.
Paint during unoccupied hours.
Keep lids on paint containers when not in use.
Ventilate the building with significant quantities of outside air during and after painting. Ensure a complete building flush before occupancy.
Use more than normal outside air ventilation for some period after occupancy.
Avoid spraying, when possible.
Pest Control Integrated Pest Management
Use or require the use of Integrated Pest Management by pest control contractors to minimise the use of pesticides when managing pests.
Control dirt, moisture, clutter, foodstuff, harborage and building penetrations to minimise pests.
Use baits and traps rather than pesticide sprays where possible.
Avoid periodic pesticide application for “prevention” of pests.
Use pesticides only where pests are located.
Use pesticide formulated explicitly for the targeted pest.
Apply pesticides only during unoccupied hours.
Ventilate the building with significant quantities of outside air during and after applications.
Ensure a complete building flush before occupancy.
Use more than normal outside air ventilation for some period after occupancy.
Notify occupants before occupation.
If applying outside, keep away from the air intake.
Shipping and Receiving
Establish and enforce a program to prevent vehicle contaminants from entering the building.
Do not allow idling of vehicles at the loading dock. Post signs and enforce the ban.
Pressurise the receiving area relative to the outside to ensure that contaminants from the loading area do not enter the building. Use pressurised vestibules and airlocks if necessary.
Periodically check the pressure relationships and compliance with the protocol.
Notify delivery company supervisors of policy.
Establish and Enforce a Smoking Policy
Environmental tobacco smoke (ETS) is a major indoor air contaminant. A smoking policy may take one of two forms:
A smoke-free policy which does not allow smoking in any part of the building.
A policy that restricts smoking to designated smoking lounges only.
(Partial policies such as allowing smoking only in private offices are not effective.)
Smoking Lounge Requirements
A designated smoking lounge must have the following features to be effective in containing ETS.
The lounge should be fully enclosed.
The lounge should be sealed off from the return air plenum.
The lounge should have exhaust ventilation directly to the outside at 60cfm per occupant (using maximum occupancy).
Transfer air from occupied spaces may be used as makeup air.
The lounge should be maintained under negative pressure relative to the surrounding occupied spaces.
Managing Moisture and Mold (See also EPA's Mold Remediation Guidelines)
Mold thrives in the presence of water. The secret to controlling mould is to control moisture and relative humidity.
Keep relative humidity below 60% (50%, if feasible, to control dust mites)
Keep all parts of the building dry that is not designed to be wet.
Adequately insulate exterior walls or ceilings to avoid condensation on cold surfaces.
Insulate cold water pipes to avoid sweating
Clean spills immediately. Thoroughly clean and dry liquid spills on porous surfaces such as carpet within 24 hours, or discard the material.
Do not allow standing water in any location.
Maintain proper water drainage around the perimeter of the building
Provide sufficient exhaust in showers or kitchen areas producing steam
Thoroughly clean areas that are designed to be wet
Wash floors and walls often where water accumulates (e.g., showers)
Clean drain often pans and insures a proper slope to keep water draining
Ensure proper maintenance and treatment of cooling tower operations
Discard all material with signs of mould growth
Discard furniture, carpet, or similar porous material having a persistent musty odour.
Discard furniture, carpet, or similar porous material that has been wet for more than 24 hours
Discard ceiling tiles with visible water stains
Pollution Transport
Air Movement and Pressure: Contaminants reach occupant breathing-zones by travelling from the source to the occupant by various pathways. Usually, contaminants go with the flow of air.
Air moves 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.
Air movement should be from occupants, toward a source and out of the building rather than from the source to the occupants and out the building. Pressure differences will control the direction of air motion and the extent of occupant exposure.
Driving Forces: Driving forces change pressure relationships and create airflow. Conventional driving forces are identified in the table below.
Major Driving Force
Effect
Wind
Positive pressure is created on the windward side, causing infiltration, and negative influence on the leeward side, causing exfiltration, though wind direction can be varied due to surrounding structures.
Stack Effect
When the air inside is warmer than outside, it rises, sometimes creating a column of rising air -- up stairwells, elevator shafts, vertical pipe chases etc. This buoyant force of the wind results in positive pressure on the higher floors and a negative influence on the lower levels and a neutral pressure plane somewhere between.
HVAC/Fans
Fans are designed to push air in a directional flow and create positive pressure in front, and negative pressure behind the fan.
Flues and Exhaust
Exhausting air from a building will reduce the building air pressure relative to the outdoors. Air exhausted will be replaced either through infiltration or through planned outdoor air intake vent.
Elevators
The pumping action of a moving elevator can push air out of or draw air into the elevator shaft as it moves.
Common Airflow Pathways
Contaminants travel along pathways - sometimes over great distances. Trails may lead from an indoor source to an indoor location or from an outside source to an indoor area.
The location experiencing a pollution problem may be close by, in the same or an adjacent area. Still, it may be a considerable distance from, and/or on a different floor from a contaminant source.
Knowledge of common pathways helps to track down the source and/or prevent contaminants from reaching building occupants.
Common Airflow Pathways for Pollutants
Common Pathway
Comment
Indoors
Stairwell
Elevator shaft
Vertical electrical or plumbing chases
The stack effect brings about airflow by drawing air toward these chases on the lower floors and away from these chases on the higher levels, affecting the flow of contaminants.
Receptacles, outlets, openings
Contaminants can quickly enter and exit building cavities and thereby move from space to space.
Duct or plenum
Contaminants are commonly carried by the HVAC system throughout the occupied spaces.
Duct or plenum leakage
Duct leakage accounts for significant unplanned airflow and energy loss in buildings.
The flue or exhaust leakage
Leaks from sanitary exhausts or combustion flues can cause serious health problems.
Room spaces
Air and contaminants move within a room or through doors and corridors to adjoining spaces.
Outdoors to Indoors
Indoor air intake
Polluted outdoor air or the exhaust air can enter the building through the air intake
Windows/doors, Cracks and crevices
A negatively pressurised building will draw air and outside pollutants into the building through any available opening.
Substructures and slab penetrations
Radon and other soil gases and moisture-laden air or microbial contaminated air often travel through crawlspaces and other substructures into the building.
Ventilation
Ventilation can be used to either exhaust pollutants from a fixed source, or dilute contaminants from all sources within a space.
Exhaust Ventilation: Ideally, exhaust airflow should be sufficient to draw pollutants from the source into the exhaust and away from occupants. The source should be located between the exhaust and the occupants. Rooms with significant sources should be under negative pressure relative to the surrounding spaces. Some sources, such as cooking stoves and laboratory benches, may require exhaust hoods. Also, see Exhaust Systems.
Dilution Ventilation: Contaminants from area sources such as people, building materials, office equipment, are diluted with outdoor air from natural or mechanical ventilation. Ventilation systems should be operated to provide sufficient outdoor air ventilation. Reducing outdoor air ventilation rates below required levels saves little energy and is not advisable. If capacity is available, outdoor air ventilation rates should meet applicable standards under all operating conditions. Problems with reduced outdoor air during part-load in specific VAV systems should be addressed.
Ventilation Measurements: Measurement instruments and techniques, which are generally available to building personnel, can be extremely useful in assessing the performance of the right ventilation system for both exhausting and diluting pollutants. Useful measuring tools include:
Smoke tube to measure airflow
Flow hood to measure air volume
Velocity meter to measure air velocity
Measuring carbon dioxide to estimate the percentage of outdoor air or to generally evaluate outdoor air ventilation
