Buildings provide security and keep us warm and dry. The building and develop creates an indoor environment where we are protected from the outside, but it also keeps the indoor emissions inside. In large parts of the world, people spend more than 90 percent of the time in indoor environments and most people spend the main part of their time in their home indoor environment. This lecture will explain about health effects of air pollution inside buildings. The indoor areas affected by what is outside the building, what goes on inside the building, and the exchange of air and pollutants. The outdoor levels of air pollution are very important for the indoor levels. The penetration of ambient air pollution such as PM 2.5 is usually around 50 percent from outdoor to indoor, depending on how tight the building is. So as much of our time is spent indoors, 80-90 percent of the actual exposure to PM 2.5 from outdoors sources typically occur indoors. We know that indoor use of solid fuel for heating and cooking is an enormous health problem in low income countries. But even in high income countries, the household use of biomass burning in stoves has significant contributions to both indoor and outdoor air pollution. Gas stove and gas are liquid fuel heating systems will also emit nitrogen dioxin and some particulate matter. But the levels are much less than with the use of solid fuels. With proper flow, chimney or ventilation, the levels will be even lower yet, they can have health effects. Cooking, frying, baking, toasting, and even electrical stoves also emit particulates. In some high income countries, candles are widely used especially in winter time to provide a cozy atmosphere in homes and restaurants. Emissions from burning candles can reduce lung function for a short time span but we don't know if there are health effects in the long run. In this laboratory test, you see that one candle burning for a few minutes increased the number of ultra fine particles per cubic centimeter from around 1,000 to almost half a million. Secondhand smoke from tobacco is another very important contributor to indoor air pollution with particulates and more than 4,000 toxic chemicals. In the lab test, a single cigarette resulted in more than 900,000 ultra fine particles per cubic centimeter. Building material, furniture, household appliances, clothing, personal care products, cleaning products, and other indoor components often emit volatile or semivolatile organic compounds, such as Formaldehyde, Phthalates, and PCBs. Some of these are carcinogenic, endocrine disruptors, or toxic in other ways. Radon is a dense radioactive gas seeping into the buildings from the soil underneath. Especially, if rich in rock material. Basements and and one-storey type buildings will have the highest levels. Radon has a short half-life but the radon donors are also radioactive and solid matter that can adhere to particles. Exposure to radon is a well-documented cause of lung cancer. In the U.S. and Europe, it is considered to be the second most important cause of lung cancer. Although, most cases will occur in smokers. Other cancers have also been suggested to be associated with radon. As human activities usually result in release of moisture, type buildings tend to be damp. Damp indoor environment allow more transmission of infectious agents, growth of mold, and house dust mites to thrive. Damp building things have consistently been associated with increased risk of asthma, although we don't know how it works. It is not only the mode and house dust mites that grows in dampness that are the causes of asthma and allergy. Dampness could also be a sign of poor ventilation that allow a lot of other indoor pollutants to accumulate. Asthma and allergy occur mainly in relative clean environments in Western urban societies reaching levels of 10-20 percent of the population, whereas rural regions and low and middle income countries are much less affected. Apparently, parasitic diseases and exposure to diverse microbial patents protect from asthma and allergy. This has led to the hypothesis that microbial balance and composition play an important role. We, the humans ourselves, also affect the air quality inside buildings. I have talked to Professor Geo Clausen, from the Technical University of Denmark about this. What happens when people are crowded in a room with poor ventilation? Well, we human beings, we emits hundreds of chemicals among these we have carbon dioxide. And when the concentration of this soup increases that begins to have an impact on first, the sensory system that we perceive the air to be stuffy and odorous. When the concentration goes up we start to see symptoms like headache, being tired, and so on. Where is that a problem? As a problem in may places, when we are many place, people gather in a space that could be a school for instances. In particular troublesome situation because we are many children gathered in the classroom and we know that on top of the things I said before that has an impact on the pupils learning. So it's very important to make sure that we have ventilation to lower the concentration of these bio pollutants that we are emitting. Tight buildings can save energy for indoor temperature control in both cool and hot climates and they can protect the dwellers from outdoor air pollution. But tight buildings also allow buildup of all the pollutants from indoor sources with all their health effects. In the European Union, it has been estimated that two million healthy live years are lost annually due to indoor air pollution. Cardiovascular diseases dominate with 60 percent of the loss. And this is to a large extent due to particulate pollution. 35 percent of the loss is due to airway diseases in terms of asthma, allergy, lung cancer, infections, chronic obstructive lung diseases, and various symptoms. These losses are associated with particulates, dampness, bio aerosols, radon, and volatile organic compounds. I asked Professor Geo Clausen what we can do to reduce indoor air pollution. How can we control the entry of outdoor air pollutants into buildings? Well, in spaces or in buildings where we have mechanical ventilation, of course, we can install a filter. A filter will mainly take the particular face out. We also have possibilities of removing gases. And it's interesting that not many years ago it was to protect the ventilation system that we install a ventilation filter. Now we're seeing a movement that we want protection about pollutants coming from outside. What can we do to control the indoor sources of air pollution? Well, this is the main thing that we need to be concerned about, source control. So we need to control the release of moisture to the air. A family of four is releasing ten liters of water per day to the indoor environment. We need to make sure that we reduce that as much as we can. We need to be careful about any combustion sources that we have indoors that could be from kitchen range. It could be from from candle burning or whatever. What chemicals we use for cleaning or what we use these chemicals for cosmetics and whatever. We need to be aware of this. This is really rule number one to control the release of substances to the indoor environment. And what can we do to remove the pollutant from the indoor environment? There's an engineering saying that goes, "Build tight and ventilate right". Unfortunately, this is a two element sentence so if you're just stuck with the first one build tight, you're going to end up in problems because you will end up with a high concentration of pollutants generated inside. So ventilation is the key word here. We need to make sure that we have sufficient ventilation to remove whatever we can't control by source control. And here, for instance, the emission of bio pollutants from human being is a good example. We need to be in our buildings of course and for that we need ventilation. What can we do about radon? Well, radon is penetrating from the ground into a buildings. We need to have tight membrane so that we're stopping that penetration. Since this is all a pressure driven, another possibilities is to have a slight under pressure underneath this membrane. So we're stopping the penetration into the building and here is very important that ventilation works but we should be concerned about the pressure, if we have an under pressure in our homes, for instance, in the basement, then we're actually promoting the penetration through whatever cracks we may have. So controlling the pressure is also a key feature here. How can we legislate on indoor air pollution? Well one area is building codes. These codes normally only apply for buildings. But let's take an example, in Denmark, we've had a regulation that we must have at least half an air chains in our homes. That's been running for many years but we know that this is not enforced and in a recent study, we found that more than half of 500 homes had lower air chains that the building codes had. The building codes in many countries are focusing on saving energy and therefore there is a certain drive to lower the ventilation so that we can save even more energy. I think this has come to a balance now there's now beginning to be more focus on the indoor environment so I think have reason to to think that in the future we will not only focus on energy saving spot the more balanced situation where we let indoor environment and energy consumption go hand in hand. To sum up this lecture, air pollution inside buildings comes from both the outside and inside sources. It is an important health problem that we can do something about with proper control of sources and ventilation. Such initiatives will support the sustainable development goals. Number three good health and well-being, number 13 climate action, number 11 sustainable cities and communities, and number 12, responsible consumption and production.
