Indoor Air Quality: Sources, Health Impacts & Ventilation

[00:00:25]Hello friends. From today onwards we will discuss  two, three or four lectures on indoor air quality.   So, today a kind of introduction we  will have about indoor air quality   that will include what is basically this indoor  air pollution? What are the causes of indoor air   pollution? What are the major sources? Then how indoor air quality is defined and   what are the historical background or perspectives  in that sense and what is the importance? Why do   we really worry about indoor air quality and what  are those important parameters that influence the   indoor air quality and then some health impacts  which are associated with different pollutants   which we get exposed in indoor environment  or micro environment of the buildings etc.   Then a few important things or  aspects like sick building syndrome   that we will discuss and what is the role  of ventilation in maintaining air quality of   indoor environment. That we will also discuss and  later on we will have concluding remarks.   So, when we talk about indoor air pollution  basically we refer to those chemical, biological   or physical contaminants which are present in an  indoor air and that may result into some sort of   health issues to the receptor, to the people who  are living inside the that particular environment.   And most of the time we feel that this air  pollution problem is only outdoor problem   or only ambient air related problem and that  may be the reason that most of the discussions   happen is regarding only ambient air quality.  We have so many standards like national ambient   air quality standards but related to indoor  air quality hardly any standard are there.   So, there is a huge gap. We think that only in  industrial areas or industrial environment or   outdoors this air quality may deteriorate and  there may be air pollution kind of thing but   fact is that the air inside the buildings or the  micro environments can be highly polluted and we   are not aware of that. Several kind of pollutants  may be there inside the buildings and we can get   exposed to that. Sometimes at times the air  pollution inside the building is more than   the ambient air and there are certain regions  we will discuss about those aspects also.   So, when we talk about the causes of indoor air  pollution, then we come across like for example   air tightness of building may be responsible  because it prevents the air exchange.   Circulation is inhibited, air circulation  is inhibited and whatever emissions are   being generated indoor like from kitchen or  from smoking or any other activity like from   dryers or washing machine or moping and  brooming, all those kind of activities,   they can generate a lot of dust or air pollutants  and they may be inside the building because this   air tightness of the building may prevent to get  them out and there may not be proper ventilation.   So, the poorly designed air conditioning or  ventilation systems also adds to the air pollution   in the micro environment of buildings. Then indoor  sources of air pollution may be there, as I said   from kitchen or from other activities we have,  even from furniture or from paints etc there may   be some passive emissions and outdoor sources  of the air pollution may also contribute to the   indoor environment because whenever we are  opening window or door then air is coming from   the outside and this inside air goes outside. So, if there are significant sources outside the   building and those sources are polluting the  ambient air that air can flush into rush into   the building, inside the building and that can  also add to the indoor air pollution.   Well so, when we talk about different sources  basically these are like whatever gases or   particulate pollution which are coming from indoor  air quality problems from homes or office related   activities and as I said, it can it can come from  outdoor activities also, whatever order outdoor   activities they can add. And these chulas or in  kitchen plus tobacco or dust from these kind of   activities they may or even when we are using  some room freshener or these are basically VOC   s Volatile Organic Compounds. They also add  into the air pollution inside the buildings.   So, sources can be several like building  materials or furnishing items or   household products like air fresheners and there  are numerous activities which can release like   even when we are doing some sort of puja, we are  burning something then whatever things are being   burnt that can add into the air pollution inside  unless we have proper ventilation system.   So, when we talk of different aspects so air  tightness of the building is one important   aspect because it prevents the air exchange  as I said and it can build up some hazardous   impact in the indoor environment as ventilation  rates are reduced sometimes we feel about like   energy efficiency that we should not go for  very high intensity or efficiency of ventilation   because then electricity bill will be very high. So, what happens sometimes people do that this   ventilation rate, they reduce to improve  the energy efficiency and the lower carbon   emissions. Those could be the reasons to achieve  but then that can result into built up of indoor   air pollutants and it can lead to development  of negative air pressure inside the building.   So, negative air pressure means  low pressure and if air pressure is   outside, the building is higher then again the  polluted air can come from outside to inside   through cracks, through whatever opening is  there through that air can come as air is   so diluted fluid, it is very difficult to  prevent it to move from one point to another.   So, you can see here, when it is shown that  of course there are ventilation systems then   some positive pressures are there proper  and then air goes out in from the inside   to outside but from outside to inside also  air comes depending upon the pressure. So,   wherever negative air pressure is there air will  come from outside to inside building, wherever   positive pressure is there air will go out from  the building to the in outdoor environment.   Then poorly designed Heating Ventilation And  Air Conditioning (HVAC), Heating Ventilation   and Air Conditioning system, if it is not  designed properly then it can also result into   several kind of pollutants like it can result into  fungi or moulds or other sickness causing microbes   or bacteria all those kind of things may happen  and that can add into allergic related issues.   So, in air conditioning duct if it is not clean  and if it is moist and it can cause microbes   related activities then it is very dangerous  to health issues and return air grill, if it is   not cleaned regularly periodically that can also  cause that can also get converted into sources of   air pollutants rather than air conditioning, it  may reduce the temperature of course but it can   add to several kind of air pollutants. So, the sources of indoor air pollution in a   typical household can be seen in this pictorial  representation. For example, from bedroom can be   there, bathroom or air conditioning units, living  room and laundry room where VOC s can be generated   by these detergents etc those kind of things,  cooking devices all these kind of activities   can add into one or the other kind of  air pollutants inside the building.   And in office buildings then there may be  additional sources like photocopying machine   can be there and heaters or some other kind of  activities, carpets capture lot of dust, if you   are not doing proper vacuum cleaning then it can  be source of lot of dust or particulate matter   of fine nature and it is very health hazard. Then, if we club them as different kind of sources   then we can say that indoor human activities can  add into the air pollution inside the buildings   and building components and furnishing  like furniture or even walls paints etc   so far set bad sets everything, dust mites can  be there all those things are the concern from   air pollutant point of view and then from outside  building also as I said, polluted air can come   inside, equipment s of different nature can  add into those chemicals leads from buildings   or when we are using chemicals in washroom  there also some fumes may be generated.   Outside the building there may be additional  sources which are of usual nature as we know   whether it is from industrial stack emissions or  pollens from different trees or plants and then   general vehicle exhaust all those kind of things  are there from parking lots, garages, orders from   different activities all those things  can be additional sources which can   add into indoor air pollution. Then there may be like these leakages from   underground fuel tanks which have petrol pumps  or any other kind of units they can have and   then moisture can also be there because if proper  drainage system is not there within the building,   if leakage is there and seepage is there,  they can also add into these kind of very   fine pollens means pores or those fungi related  issues and they can add into some microbes   which are health hazard basically. Equipment s, we have exhaust fan etc,   if you are not cleaning them properly they can  also be like sources of air pollutants. Even those   air cleaners, now a days people use air cleaners  or air filters if you are not cleaning regularly   those air filters rather than cleaning the indoor  environment they can add into air pollution. So,   it has to be cleaned regularly. So, all those kind  of equipment s if you are not maintaining them   properly they can add into indoor air pollution. So, whether it is heating ventilation air   conditioning related equipment or non-HVAC  means non-heating ventilation air conditioning   equipment, like solvents or toners all those kind  of cleaning processes all those can emit one or   other kind of indoor air pollutants. Different human activities as we know,   we are using some pest control related chemicals  pesticides etc they also add into pollutants   inside the building, house activities are  there like airborne dust or dirt and then   cleaning materials all those  things are there for adding into   the air pollution inside the micro environment. Personal activities like smoking, cooking,   body odour, if we are not clean then we are  also adding into some air pollutants. Our pets,   if we are not keeping our pets properly  clean then they can add into several kind of   air pollutants. Their hair and many things may  be there, cosmetic order can be there, all those   things. Whatever we are using which smell that  is basically adding to the air pollution.   Then building components and furnishing as  we discussed like surfaces or open cells or   deteriorated furnishing items materials  containing damaged asbestos all those kind   of things are there, then unsanitary conditions  like microbiological growth on soiled or water   damaged furnishing, microbiological growth may  be there in those surfaces which are moist or   and dry traps may be also there which can like  sewer gas related issues can also be there. So,   order causing activities can be there for  adding into indoor air pollutant.   Other sources like because accidentally some  liquids are spilled that can also add into   some sort of pollution. Then repair activities,  when whenever we do that also adds into some   kind of air pollutants. And now we come to indoor air quality   because whatever we have discussed are adding  to the indoor air quality. They are leading us   to the quality of indoor air. So, how do we define  what is the indoor air quality. So, theoretically   we can say that it refers to the air quality  within the buildings or structures wherever we are   living whether it is residential building or the  office building especially as it relates to the   health and comfort of the building occupants. When your room is properly tight, I mean   improperly tight I would say and it is not  ventilated properly then lot of suffocation   can be there. CO2 build up may be there and  you are not having proper oxygen for your body   and ultimately you may fall sick. So, indoor air  quality is basically defined by the depiction of   concentrations of different pollutants and thermal  conditions plus humidity related issues also.   And some air pressure if it is having  negative kind of thing, so then   different air pollutants come from outside and  they have health the impacts of negative nature   discomfort and performance of buildings of  occupants, performance means working performance   can reduce, efficiency can reduce, you may fall  sick you may not attend your school or college or   office and you have to visit the doctor because of  some respiratory problems and that may be because   of this poor indoor air quality. So, again as we talk about   what is the significance of indoor air quality  in terms of household air pollution. So, it is   given data 3.8 million die prematurely  every year from household air pollution. So,   from cooking, this is 2016 data. So, those kind of  things are there which really alarm that we should   be careful about the indoor air quality. So, why do we study? The reason we know because   it is affecting our health and environmental  protection agency has given some data like   people spend over 90 percent of their time  indoors now a days and if you look at this corona,   means the whole world almost everyone was in  inside the their houses. Their outdoor activities   was restricted very severely. So, even this lifestyle is becoming, so   that most of the people whether they are working  in factories or in offices, they are working in   some indoor environment and the air pollutants in  those micro environments are 2 to 5 times higher   than the outside. That has been observed because  of those observations, these are the data.   World Health Organization also has estimated that  more than 30 percent of all commercial buildings   have significant indoor air quality problems. So,  that means the severity of this indoor air quality   is affecting a lot of people, a lot of population  and we should worry about it. We should do   something to improve the indoor air quality. Now if you talk about historical perspective   whether in past those centuries,  this was the issue or not? So,   when we go about the literature then we find that  ever since men first lit the fires in shelters,   in caves so indoor air quality has been a health  issue. Basically, there are evidences of such   nature that lungs were blackened because of that  particle deposition and it has been seen in this   mummified human remains which were discovered  in Egypt and Peru and those countries.   So, indoor air quality became an important topic  in 18th century very much because of lot of this   coal burning and fossil fuel reuses and the first  regarding deaths of workers in mines basically   and those kind of activities, when the slavery was  there, so from Africa to America when ships were   filled with so many people and ventilation was not  proper, so many people died and that was basically   because of poor air quality. And then we talk about this first   indication of indoor contamination in terms of  asbestos concentration or asbestos pollution. This   is a carcinogenic substance as you know and this  was discovered by epidemiologists. So, in a 1970   study it was found that less rate of ventilation  then higher concentration of radon, source of the   radon was building material and on July 12, 1989  environmental protection agency issued a final   rule banning most asbestos containing products. So, whatever building material having asbestos,   so that was discarded or banned for uses for the  building material purposes. Indoor air pollution   importance of indoor air quality in terms  from solid fuels when we are using coals etc,   it accounts for 3.5 million deaths and 4.5  percent of global daily adjusted life here.   This kind of data are there from a study and  it also accounted for 16 percent particulate   matter pollution. So, that way it is a very  significant issue that indoor air quality has   to be clean otherwise large number of population  can get exposed to its harmful effects.   Then what are the parameters which effect or  influence the indoor air quality. So, when we list   them like rate of exchange of air from outdoor  like ventilation outdoor to indoor what is the   air mass exchange which mechanical engineers  usually read about or study about and the   concentration of pollutants in the outdoor  air, rate of emissions from sources indoors,   rate of removal of pollutants like sinks are  there, some indoor temperature indoor humidity,   age of the indoor structures or building  material, type of foundation soil.   Because if it is contaminated like  suppose it was a landfill site   and you have constructed buildings there, so  maybe some very harmful chemicals are there and   slowly they come out of the soil and they fill  up complete the building atmosphere and you   never know this can happen and later on we find  that certain health issues are there.   When health impacts of indoor air pollution  are discussed, the reduction in oxygen level   of species are the reasons, those are the  reasons like increase in CO2 level, as I said   when you feel suffocated because CO2 increases in  lot of quantity then temperature may also increase   because of certain activities, increase  in humidity can also add into discomfort,   increase in bio-resource and order  that can also affect our daily life.   Well, when we talk about short term and long  term health impact of indoor air pollution.   So, short term like it can cause headache or  it can cause some irritation to nose, throat,   infection eye inflammation coughing and painful  breathing those kind of issues. Now in winter   many people have these issues and pneumonia or  skin irritation all those things can be in term   short term kind of effect are there because of  polluted air inside the micro environment.   When we talk about long term effects so it can  affect the central nervous system, the headache   anxiety all the time. Cardiovascular disease can  also be there, heart related disease can also   there, then respiratory diseases like asthmatic  problems may occur or even cancer causing things   can also be there because of constant exposure  to the polluted air inside the buildings.   When we talk about the pollutant specific effects,  there health effects whether it is outside the   building or inside the building it is the same  like knocks is causing irritation to the skin   or eyes and the throat and it can cause coughing  also and there are some limits are given there   by environmental protection agency. Some  standards are there, this should not exceed   these are the limits, CO is having like headache  even in fact CO as you know, it can cause death   also if high concentration of CO is inhaled  and we do not get aware of it because it   does not smell or this is odourless, colourless. RSPM, this Respirable Suspended Particulate Matter   that is PM10, that can cause cancer  also if carcinogenic elements are   coated in those particulate matter whether it is  PM2.5 or those fine particles they can enter into   our system. SO2 means sulphur dioxide can  result into lung disorder or shortness of   the breath those kind of things may be there  and this radon can cause lung cancer.   Similarly, there are like formaldehyde asbestos  all these are very healthy effects can be there   like formaldehyde can skin allergies can result  from that, asbestos can cause lung cancer,   pesticides again they are can result in skin  diseases, VOC s they can have eye irritation   or skin dresses, CO2 well surrogate index of  ventilation because CO2 is more than ventilation   is not good and when CO2 is more and oxygen is  less then you feel uncomfortable. Ozone many times   we have discussed that it is very problematic and  it can cause several kind of problems.   When we come to sick building syndrome, you might  have heard this terminology sometimes you might   heard like some building is blamed like  if somebody goes and the family goes there   they always fall sick. Sometimes we mark  a building saying this is ghost building,   all those kind of things are there, sometimes  they say do not live in that particular building,   it is cursed. Anybody or any family  come to this building, they fell sick.   So, basically that may be because of certain  these indoor air pollutants also. So, that is   terminology sick building syndrome is there.  So, this term basically is used to describe   situation where building occupants experience  some acute health related issues. Whenever you   live in there, then you have breathlessness  or some heart related problem or whatever   depending upon what kind of pollutant is there. So, specific illnesses may be there some causes   can be identified related to the pollutants.  So, the poor lighting, poor indoor air quality,   poor ergonomics means you can fall if it is not  designed properly and then you can say that this   is cursed building, we cannot live healthy here  uncomfortable acoustics, psychological stress   because if light air all those combinations  are not proper then you do not feel good.   So, those may be the buildings which are known  as or result into sick building syndrome. And   the solutions for that we should really care about  this lighting, air circulation all those things.   So, we can solve that problem and the air  cleaning, increasing ventilation rates and   proper communication with the residents and  monitoring of the pollutants and then identifying   the sources of those pollutants, removing them  that kind of thing can be done to make that   building as healthy living space. Well, ventilation plays very important role   for removing the pollutants from inside  to outside. And sometimes as I said,   ventilations can even increase the pollutants  also if it is not properly designed. So,   there may be natural ventilation, there can be  mechanical ventilation or the hybrid system can   also be there. So, those things can be seen, here  you see the ventilation rate, air flow direction,   air distribution all those things basically  play important role otherwise some corners   of the building will be highly polluted  if ventilation is not proper.   If you talk about natural ventilation, it can  be in terms of like single sided ventilation or   cross ventilation, stack ventilation all those  kind of things can be there. And in natural   ventilation basically you can see here these  species where circulation happens properly but   it can bring pollens and other pollutants from  outside air if it is not properly designed.   Because natural ventilation means you  allow air from outside to come inside and   from inside to outside with some ventilators which  are naturally taking this circulation of the air.   So, that way we are not controlling outside  air, it is coming just from some openings. So,   that may be one issue. If it is not clean  air outside then it can be an issue.   Mechanical ventilation basically it can  control. The air flow, speed, volume,   temperature everything you can control because  mechanically it is designed and that way cool   air can come down and then this warm air goes  up and it can get out with those particularly   systems which are designed for ventilation. So, you can see here like in natural ventilation   there may be some pockets where high level  of pollutants may be there because natural   ventilation cannot go to each and every  corner with uniform flow rate of the air.   It has some limitations but mechanically  designed proper ventilation system can have   uniform distribution of air circulation and  that can remove the pollutants properly.   In hybrid or mixed mode ventilation there are this  combined natural driving forces you use and then   whenever this natural pressure difference  is not there, then you use the mechanical   devices for proper ventilation. When we talk about like assessment of   ventilation performance, so we have certain  these kind of questions which really help us to   see whether the ventilation system is performing  properly or not. For example, does this system   provide sufficient ventilation rate as required?  You can calculate that. Is the overall airflow   direction in a building is from clean air to  dirty zones so that the dirty zones flush out   and then how efficient is the system in delivering  the outdoor air to each location in the room.   And how efficient is the system in removing the  airborne pollutants from each location in the   room, so that room is having clean air. So, those  kind of things can be seen and for assessment   or evaluation of ventilation system. Well, in totality when we talk about ventilation   and indoor air quality. So, basically the energy  efficient residential buildings having mechanical   ventilations with the heat recovery, they are  proved that with the lower concentrations of   indoor particulate matter PM10 or PM2.5 carbon  dioxide or VOC s compared to the conventional   apartments which do not have the weather properly  controlled mechanical ventilation system.   So, that picture shows that in that proper  like ventilated system which is controlled   mechanically you can have healthy environment in  comparison to the conventional apartments. So,   that is one important aspect that if you  want to have good indoor air quality have the   good ventilation system. So, that you live in a  better condition and you do not fall sick, you do   not get exposed to indoor air pollutants. So, this is conclusions from this introductory   lecture. We can say that the indoor air quality  assessment and management need more attention as   increasing number of people are spending more and  more time indoor environment. Whether it is office   or our residential buildings and the understanding  and controlling the sources and dispersion and   diffusion of common indoor air pollutants can help  to reduce the risk of indoor health impacts.   And proper ventilation is required  to keep indoor environment healthy   in terms of better indoor air quality. So, I  hope with this introductory lecture, I am sure   you can visualize what the importance of  indoor air quality is and which are the sources   important, sources or major sources  which can deteriorate the indoor air   of the micro environment whether it  is library or your residential house   or office building or office room, whatever. So, with this I finish this lecture and   we will continue discussing about other  aspects of the indoor air quality.   These are the references for more information  on indoor air quality, please go through that   whenever you have time and thanks again.  See you again in the next lecture. Thanks.