• Chapter 6: Air Quality

    • Chapter 6: Air Quality

    Vocabulary List


    Case Example 1

    A small mining community was experiencing an especially cold winter. To get through the cold months, most of the residents relied on heat from burning wood in their stoves to heat their houses. In addition to the cold, there had been a period of about one week where they had very little wind. The state university was located about 160 kilometers (100 miles) away from the town but had a remote air monitoring station in the community. Researchers began to get concerned as the Air Quality Index (AQI) in this community rose from average levels to low 300’s, which are classified as Hazardous. Residents were urged to stay inside and not burn as much wood. After about five days of hazardous levels of air quality, 16 of the residents showed up at a hospital complaining about nausea, difficulty breathing, stinging eyes, and burning throats. Although all of them fully recovered, one resident who was asthmatic was hospitalized for almost three weeks before recovering.

    Case Example 2

    In a high-altitude community in Southern Africa, in an area where there are harsh weather conditions, a family collected wood and animal dung for fuel to help them survive the winter months. The house was a round rock dwelling with a thatched roof. In order to cook and heat the house, a fire was built in the center of the house. Smoke from the fires often filled the one room house and there were soot stains down the walls,within four feet of the floor. After years of exposure to the smoke, the parents both died from lung cancer, leaving their 17-year-old daughter to take care of the rest of the children.

    Poor outdoor air quality can lead to acute exposures that can cause people to get really sick; however, chronic exposure to poor indoor air quality can be just as bad for those who are exposed to it.

    Introduction

    Air Quality

    Air pollution is the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. The World Health Organization (WHO) data shows that in 2019, almost all of the global population (99%) breathed air that exceeds the WHO guideline limits and contains high levels of pollutants (World Health Organization). Air pollution is a complex mixture of solid particles, liquid droplets, and gasses. It can come from many sources, including household fuel burning, industrial chimneys, motor vehicles, traffic exhausts, power generation, open burning of waste, agricultural practices, desert dust, forest fires, and many other sources (World Health Organization, 2021). Air pollution is one of the greatest environmental risks to health. By reducing air pollution levels, countries can reduce the burden of disease from stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma. The lower the levels of air pollution, the better the cardiovascular and respiratory health of the population will be, both long and short-term. Most sources of outdoor air pollution are well beyond the control of individuals and demand joint action by local, national, and regional-level policymakers working in sectors like transport, energy, waste management, urban planning, and agriculture (World Health Organization, 2022).

    Stroke, heart disease, lung cancer, and both chronic and acute respiratory diseases, including asthma.

    Ambient or Outdoor Air Quality

    Millions of people live in areas where air pollution can cause serious health problems. Local air quality can affect our daily lives. Like the weather, it can change from day to day (AirNow, a). Many conditions can affect air quality such as weather, geographical location, and population. The main sources of outdoor air pollution include emissions from vehicles, exhaust from power plants, and releases from agriculture sites and waste management facilities. There is little that most people can do about controlling outdoor air quality; however, being aware of the local pollution levels and making smart decisions can help prevent from being overexposed to poor outdoor air. To help make those decisions, the United States Environmental Protection Agency has worked with other organizations to develop a tool that people around the world can use. It is called the Air Quality Index (AQI) and information about it can be found at  https://www.airnow.gov/.

    The AQI uses color-coded categories and provides statements for each category to tell you about air quality in your area, which groups of people may be affected, and steps you can take to reduce your exposure to air pollution. It’s also used as the basis for air quality forecasts. Think of the AQI as a meterstick that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality. The AQI is divided into six categories. Each category corresponds to a different level of health concern. Each category also has a specific color. The color makes it easy for people to quickly determine whether air quality is reaching unhealthy levels in their communities (AirNow, b). Below is the AQI description chart.

    A chart describing AQI categories. First, green is considered good with index values of 0 to 50, when air quality is satisfactory and air pollution poses little or no risk. Next, Yellow is moderate with levels between 51 and 100, when air quality is acceptable. However, there may be a risk for some people, particularly those who are usually sensitive to air pollution. Next is orange, which is unhealthy for sensitive groups and has levels between 101 and 150. Members of sensitive groups may experience health effects. The general public is less likely to be affected. Next is red, which is unhealthy and has levels between 151 and 200. Some members of the general public may experience health effects, and members of sensitive groups may experience more serious health effects. Next is purple, which is considered very unhealthy and has levels between 201 and 300. Health alert: the risk of health effects is increased for everyone. Last is maroon, which is hazardous. This is levels 301 and higher, and there is a health warning of emergency conditions: everyone is more likely to be effected.

    To find out what the AQI is in your community, go to www.airnow.gov and enter your location. It will give you the AQI number as well as a forecast and possibly recommendations. Another way to find your daily AQI is to visit https://www.iqair.com/air-quality-map, which has an interactive world map and uses satellites and reporting stations to create a visual representation of the outdoor air quality levels throughout the world.

    Indoor Air Quality(IAQ)

    Household or indoor air pollution was responsible for an estimated 3.2 million deaths per year in 2020, including over 237,000 deaths of children under the age of five. Exposure to indoor or household air pollutants can lead to a wide range of adverse health outcomes ranging from eye conditions to respiratory illnesses and cancer. Almost half of all deaths due to lower respiratory infection among children under five years of age are caused by inhaling particulate matter (soot) from household air pollution (World Health Organization, 2022b). There are many sources of indoor or household air pollution such as carbon monoxide, household chemicals, and mold. Unlike outdoor air pollution, the average person has more control over their own exposure to indoor pollutants.

    Eye conditions, respiratory illnesses, and cancer.

     

    Indoor Air Quality Surveys

    Health departments, as well as professional consultants, may conduct indoor air quality surveys to help people or businesses identify indoor pollutants and their levels. There are thousands of chemicals or substances that can affect indoor air quality. In some situations, the person or business may know exactly what they want to be tested. If the pollution source is unknown, the inspector must narrow down the possible sources of pollutants. This can be done by interviewing people that work or live in the area or by visiting and observing the area. If the business has a lot of workers, it may be easier to send out a questionnaire rather than interview every employee. After determining what will be tested, the inspector can create a sampling plan and move on with the testing. After testing, the results will be compared to the appropriate standards or recommendations for that source of pollution. The final step is writing a report that includes the conclusions and recommendations, sometimes followed by a presentation to the company or individual who hired them.

    IAQ Sampling and Testing

    Just as there are thousands of pollutants, there are thousands of tests that can be conducted and protocols followed to collect samples. This section will address only a few of the possible tests that can be used to test indoor air quality.

    General Air Quality

    General air quality measurement may include air temperature, relative humidity, carbon dioxide, and carbon monoxide. Usually there is an electronic monitor that can be used to collect these instant readings. Temperatures can affect how people feel and work. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends that indoor range from 20°C to 24°C (68.5°F to 75°F) in the winter, and from 24°C to 27°C (75°F to 80.5°F) in the summer. ASHRAE also recommends that relative humidity in occupied spaces be controlled to less than 65% to reduce the likelihood of conditions that can lead to microbial growth.

    Carbon dioxide is created by exhaled breath, so levels are affected by the amount of people in a room, the size of the room, and how well the ventilation system works. ASHRAE recommends no more than 700 parts per million (ppm) above outside levels. Since outdoor levels are around 400 ppm, indoor levels should be below 1100–1200 ppm. Most ventilations systems are designed to maintain carbon dioxide below 1000 ppm (CDC, 2022).

    Carbon Monoxide (CO) is a colorless, odorless gas that is released when something is burned. Any type of appliance such as cook stoves, hot water heaters, washers, and dryers that run on natural gas can release CO. Additionally, vehicular exhaust in garages can also increase indoor levels of CO. At low levels, CO can cause a person to feel tired and can affect their thinking; however, at high levels, CO can cause death. Worldwide cumulative death rates from CO poisoning are estimated at 4.6 deaths per million (Mattiuzzi & Lippi, 2020). The Occupational Safety and Health Administration (OSHA) sets the permissible eight-hour exposure limit for CO in a workplace at 50 ppm. At levels of 3,000ppm, death can occur in less than 30 minutes.

    Volatile organic compounds (VOCs)

    Volatile organic compounds (VOCs) are vapors that come from liquid chemicals. VOCs can concentrate indoors and cause some health effects such as an aching head and irritation of the throat, eyes, and nose. VOCs come from a variety of materials such as new building materials, new furniture, carpet, paints, cleaners and glues. Although there are countless VOCs, the main ones can be tested easily. A passive monitor left in a room can be analyzed for up to 30 VOCs at a time. Permissible exposure limits can often be found at the bottom of the page of sampling results.

    Mold

    Mold is a fungus that easily grows indoors; all it needs is water, food, and the right temperature. Mold can cause allergy type symptoms such as watery eyes, sneezing, and a runny nose. The type of mold sampling you conduct is based on what your goal is for your sampling. The information that each test gives is dependent on which test you select. There are two basic types of mold testing. They include surface sampling and air sampling. Below will be a brief description of how to conduct the various types of testing as well as the type of information you will receive from them.

    There are thousands of species of mold and most have there own unique life cycle. A generic life cycle will be discussed that represents several of the molds responsible for indoor problems.

    First there is a viable mold spore floating around in the air. Eventually that spore will settle out of the air and land on a surface. If the temperature is conducive and that surface is organic such as wood, and there is water present, the spore will begin to germinate. Thread like appendages will begin to grow out from the spore into the surface material. These appendages are called hyphae. Hyphae digest nutrients by excreting enzymes that breakdown the organic material. That material is absorbed back into the hyphae that continue to grow. If there is more than one spore, the hyphae begin to interconnect and form a mature matrix called mycelium. From this mycelium fruiting bodies rise into the air. At the end of the fruiting body there is a conidiophore. The conidiophore houses the maturing conidia. The conidia mature into spores and the mold sporulates sending the spores into the air. If there is enough growth you eventually have a colony.

    Below is a visual representation of the mold cycle:



    Just like the fire triangle where you need three things in order to have fire, mold growth requires 3 things to grow. A colony of mold produces millions of mold spores. Fortunately not all mold spores are viable. Viable means that the spores are able to germinate, grow and reproduce. If you have all three legs of the mold triangle but you don’t have a viable spore there will not be mold growth. Let’s begin with a viable mold spore. In order for the spore to germinate and grow it needs water, food and the proper temperature. Removing any one leg of the triangle will stop the growth of mold.

    All mold growth requires water however there are some species of Aspergillus that require very little water. On the other end of the spectrum are species of Stachybotrys that prefers lots of water. Stachybotrys does not compete well initially against other types of mold, however, given plenty of water over a long time it will take over. When Stachybotry is found in samples it often indicates that generous water exposure has been there for a long time.

    Most mold species prefer organic materials that can be further broken down. Cellulosic materials such as paper straw and wood are amongst molds favorites.

    Our bodies are made out of organic material and water fortunately most molds do not grow at high temperatures such as normal body temperature. Aspergillus Fumigatas is one of the few molds that is capable of growing inside the body and can cause the condition aspergillosis. Most molds are mesophillic and thrive at normal room temperatures, while there are a few that can handle cold temperatures.

    Below is a visual representation of the mold triangle:


    In most cases, mold is a fairly easy thing to deal with. The first and most important thing you should do is address the moisture source. If the additional moisture is coming from a leaking pipe, replace it. If the problem is from unwanted condensation, you will need better insulation in the affected area. If the moisture is in the air, or you are experiencing high humidity due to your work environment or regional weather, a dehumidifier may be helpful. By addressing the moisture problem, you will prevent further mold development.

    Secondly, you will need to clean and neutralize the current mold spores. A bleach solution of about 200 parts per million will generally work well. However, in some persistent places, or where the mold colonies have embedded deep into porous materials, you will need a stronger solution of 500 ppm. In most cases, two tablespoons of commercial bleach to one gallon of water is more than enough. Spray the solution onto the affected area and let the solution soak in for about five minutes. Spray it again and scrub it clean. A hard bristle brush (or a toothbrush in tight spaces) will get into cracks and wherever else the mold spores are hiding.

    Surface Testing

    Surface testing requires the tester to physically touch a surface that may or may not contain mold. Most surfaces contain a normal amount of spores that naturally settle on the surface, while others will contain actual mold growth. There are two types of surface testing: tape samples and swab samples.

    Tape samples require clear tape and regular size microscope slides. The tester will break off a 10cm (4-inch) strip of tape. The tape will be placed directly on the assumed mold growth or on any surface. A little pressure is applied to make sure the tape meets the surface. (If it is a paper surface, do not press too hard or the paper will stick to the tape also.) Next lift the tape up off the surface and place it on a clean microscope slide so that a little bit of tape folds over the ends of the slide. Next, write your sample number in a clean area of the slide and prepare the slide for shipping to the lab.

    The first information that a tape sample gives you is whether there is actual mold growth on the surface or just normal fall out. If the tape sample collects mycelial fragments, hyphae, fruiting bodies, or conidia along with the spores, you have mold growth. If the sample only contains spores, then the results are listed as normal fallout. Spores are continuously falling out of the air and landing on surfaces so finding spores is a normal circumstance. The second thing that tape samples give you is the type of spores or mold growth present. Tape samples don’t give you the quantity of mold spores. Other than a simple adjective referring to light (moderate or heavy deposition), there is no reference to total number or concentration. Secondly, tape tests cannot tell you if any of the spores are viable (able to grow and reproduce).

    A swab sample only requires a simple swab. The tester will take the swab out of its container and wipe it back and forth on the surface while slowly twisting the swab. A successful sample should have a dark discoloration of the swab head. The swab is returned to its container, a sample number is written on the container and the sample is prepared to be sent to the lab. Just like a tape sample, a swab sample will tell you if there is mold growth on the surface or just normal fall out. The swab sample can also give you type of mold growth or spores, but not a total or concentration. In some rare cases, the swab sample can be transferred to an agar dish to check for viable spores. Swabs are good for hard-to-reach places where it is difficult to fit a strip of tape.

    Air testing

    Air testing requires the tester to set up a sampling cassette hooked to an air pump. The pump must be calibrated to pull the correct amount of air. The cassette will mainly collect spores from the air and occasionally will catch parts of mold. There are two main types of air testing. They are sampling using a spore trap or a biocassette.

    A spore trap is a sampling cassette that is connected to a high flow such as a biopump. The pump is set to pull 15 liters of air per minute for five minutes. As air flows through the cassette all particulates, including mold spores, are deposited on a sticky substance on a small microscope slide inside the cassette. The cassette is sealed, labeled, and sent into the lab, where it will undergo direct microscopic reading. When spore traps are collected, one or two outdoor samples should be collected for background readings. Spore trap results do not necessarily indicate that there is mold growth. They will give a total spore count and concentration in the air. If the indoor samples are higher than outside, then it is possible that there may be mold growth somewhere indoors. The total spore count includes both viable and non-viable mold spores. The spore trap will also identify the species of mold spore as well as the concentration for each species.

    A Biocassette is basically an agar plate with a perforated cover and a sampling port in the side. A high-volume pump capable of pulling 28.3 liters per minute is calibrated and then hooked up to a biocassette using plastic tubing to connect to the sampling port. The biocassette is either placed on a stable surface or connected to a tripod. The paper cover is removed from the perforated biocassette cover and the pump is turned on and left to run for five minutes. At the end of the sample, the paper cover is returned, and the sampling port is covered with a cap. A sample number should be placed on the biocassete and it should be prepared to send off to the lab.

    This test cannot be used to determine if mold is present, only if spores in the air are viable. The biocassette uses special agar in which the viable spores can grow and colonize. The results of this test will give the number of Colony Forming Units (CFU’s) found on the agar plate. All CFU’s are identified by species and an air concentration is calculated. A biocassette can help identify the dangerous aspergillus fumigatus that can grow at body temperature and can lead to aspergillosis especially in hospitals.

    Written Report

    After an inspector finishes the survey, they should use the notes from the inspection along with the sampling results to write a survey inspection report. The body of the report should include the following:

    References


    AirNow. (a). Air Quality Index (AQI). Retrieved Jan 12, 2023, from https://www.airnow.gov/aqi/

    AirNow. (b). Air Quality Index (AQI) Basics. Retrieved Jan 12, 2023, from https://books.byui.edu/-XCHU

    CDC. (2022). Indoor Environmental Quality. https://books.byui.edu/-hrBb Retrieved Jan 12, 2023, from

    Mattiuzzi, C., & Lippi, G. (2020). Worldwide epidemiology of carbon monoxide poisoning. Human & Experimental Toxicology, 39(4), 387-392. https://10.1177/0960327119891214

    World Health Organization. Health topics Air pollution . Retrieved 29 December 2022, from https://books.byui.edu/-JfA

    World Health Organization. (2021). What are the WHO Air quality guidelines? Retrieved 29 December 2022, from https://books.byui.edu/-cjEM

    World Health Organization. (2022). Fact Sheet- Ambient (outdoor) air pollution. Retrieved 29 December 2022, from https://books.byui.edu/-ygsk


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