“Breathing clean air is every child’s human right,” says grassroots campaigner Rosamund Adoo-Kissi-Debrah (see TED talk) sharing the heartbreaking story of her seven-year-old daughter, Ella Roberta, whose asthma was triggered to a fatal point by air pollution.
If passed into UK legislation, ‘Ella’s law’ would enshrine the right to clean air as a priority in the work of all government departments. This would also require building operators or owners to report on and measure concentrations of airborne contaminants for the places people live and work. Public buildings would also fall under the scope of this requirement for the assessment and monitoring of air quality.
Children’s exposure to pollutants may cause severe damage, since they inhale a larger volume of air.
Let’s realize — it is a health issue.
Several research studies have ranked indoor pollution among the top environmental risks to public health in recent years. Good indoor air quality (IAQ) is an essential component of a healthy indoor environment and it significantly affects human health and well-being.
Every year acute respiratory illnesses, such as colds and influenza, cause an estimated 18 billion upper airway infections and 340 million lower respiratory infections, resulting in more than 2.7 million deaths and billions of dollars in economic losses.
Respiratory infectious diseases are spread mainly by airborne transmission, which is the inhalation from the air of virus or bacteria-laden particles generated during breathing, speaking, and all other human respiratory activities. Protecting building occupants from airborne infection in all shared interior spaces must be strategically controlled.
Pollutant concentrations in schools are higher than concentrations in households and commercial buildings. Children and adults bring chalk dust, fungi, bacteria, and viruses into the school environment, and vapors and odors from laboratories and art courses are also common sources of pollutants in schools. Schools have also, always been a second home for the pupils, and they spend most of their time indoors while at school (almost 12% of their time inside classrooms). Schools are among the critical social infrastructures in society and are often the focus of children’s social activity.
Classrooms are typically more congested than other workplaces, with an occupancy density of approximately four times that of office buildings.
Young pupils are a different segment of the population from adults in many ways, and they are more exposed to a poor indoor environment: They breathe in more air per unit weight and are more sensitive to heat/cold and moisture. The respiratory, immunological, reproductive, central nervous, and digestive systems of children are not fully matured. The route of breathing, nasal versus oral, as well as the efficacy of the nose with aerosols, may also vary between children and adults, exposing children’s lungs to higher quantities of air pollutants. Thus, their vulnerability is higher than adults, and poor conditions may affect proper development.
Inhalation exposure to air pollution increases children’s mortality rate, acute respiratory disease, and asthma. The VOC pollutants are among the leading indoor air pollutants causing severe health issues for children and adults. There is a direct relationship between the concentration of the microbial VOCs and the presence of asthmatic symptoms in pupils. Specific VOCs, such as benzene and formaldehyde, recognized carcinogens, have been strongly connected to health effects. Lack of adequate air change and ventilation rates increased the concentration of indoor contaminations, including VOCs.
The VOC concentrations in newly built or recently renovated school buildings may be significantly higher than ordinary ambient levels.
Some of these emissions can be prevented by using low-emitting materials like improved plastics and paints and solid wood or old furniture. In addition, sealing and storing the liquid materials (paints, adhesives, cleaning products, etc.) and minimizing storage periods can mitigate pollution to some extent. Pupil activities and vacuum cleaning are important sources of particle resuspension of small and larger particles, 2.5–10 μm in size.
Indoor air quality = productivity
“We have been ignoring the 90%. We spend 90% of our time indoors and 90% of the cost of a building are the occupants, yet indoor environmental quality and its impact on health and productivity are often an afterthought,” said Joseph Allen, assistant professor of exposure assessment science, director of the Healthy Buildings Program at Harvard. “These results suggest that even modest improvements to indoor environmental quality may have a profound impact on the decision-making performance of workers.”
The primary purpose of a school is to provide children with the optimal environment for their learning and development. Research has shown that the level of CO2 in classrooms can increase to very high levels due to inadequate ventilation rates. The CO2 concentrations are high in most school environments since a natural ventilation system is a primary approach to improving indoor air quality.
Pupils who study in well-ventilated offices have significantly higher cognitive functioning scores than those who work in offices or schools with typical levels.
Pupils tend to feel comfortable in indoor climates that are generally cooler than environments where adults feel thermally neutral. A healthy learning environment can reduce the absence rate, improves test scores, and enhances pupil/teacher learning/teaching productivity.
The Figure below shows that increasing the ventilation rate in classrooms to 10 L/s per person would bring significant benefits and improve learning and reduce absenteeism. It was found that the CO2 concentration should be kept at or below 900 ppm.
Figure 1: Performance of schoolwork (speed), national and aptitude tests and exams, and pupils’ daily attendance as a function of classroom ventilation rates
To assess a building’s indoor air quality, considerations include the level of stuffiness, amount of gaseous pollutants and odors, and amount of particulate matter. The stuffiness of air is generally determined by measuring the level of CO2, while volatile organic compounds (VOCs) are measured to evaluate the level of pollutants. For example, the normal concentration of CO2 in outdoor air is between 250-350 ppm (parts per million), where a typical indoor space with a good air exchange ranges from 350-1,000 ppm.
At upwards of 1,000 ppm, inhabitants may start to complain of drowsiness and poor air. When levels reach 2,000-5,000 ppm, the air feels noticeably stale, stagnant, and stuffy and can cause headaches, sleepiness, poor concentration, loss of attention, and even increased heart rate and slight nausea.
The workplace exposure limit in most jurisdictions is 5,000 ppm for an 8 hour period. Also, VOC levels are commonly 2-5 times greater indoors than outdoors due to the many household products that release these chemicals.
Measuring the amount of particles in the air includes both “respirable suspended particles” and “fine particles,” which refer to two different sizes of particulates and the respective levels at which they cause discomfort and health implications. The larger particles (smaller than 10 micrometers) are dangerous at a level of 20 micrometers per cubic meter. Particles under 2.5 micrometers should not exceed 10 micrometers per cubic meter and are used to determine the air quality indexes commonly seen in large cities.
In one of the studies, the researchers looked at people’s experiences in “green” vs. “non-green” buildings in a double-blind study, in which both the participants and the analysts were blinded to test conditions to avoid biased results. Cognitive performance scores for the participants who worked in the green+ environments were, on average, double those of participants who worked in conventional environments; scores for those working in green environments were 61% higher. Measuring nine cognitive function domains, researchers found that the largest improvements occurred in the areas of:
· crisis response (97% higher scores in green conditions and 131% higher in green+)
· strategy (183% and 288% higher)
· information usage (172% and 299% higher)
A recent study found that both subjective and physiological sleep quality is better in environments with low CO2 concentrations. Results showed that sleep quality decreased significantly with the increase of CO2 concentration, and the comprehensive questionnaire score at 3000 ppm was only 80.8% of that at 800 ppm. Other studies show that CO2 concentration often reaches > 4000 ppm in non-ventilated bedrooms. If opening a window is not possible, opening the bedroom door can help dilute exhaled CO2.
There are very few assessment studies on the impact of improving classroom air quality on socio-economic benefits. Wargocki et al. estimated the benefits of improved ventilation in Danish classrooms. Assuming that all Danish classrooms are ventilated at a rate of 6L/s per person, which is the case for about 50% of classrooms, an assessment was made of the benefits that might be obtained if the ventilation rate is increased to 8.4L/s per person, which is the requirement in Sweden. Using the Danish Rational Economic Agency Model (DREAM), it was estimated that improvements in ventilation would yield an average annual increase in the gross domestic product (GDP) of €173 million and an average annual increase in the public budget of €37 million in the following 20 years. The impact is generally due to more pupils completing their education under favorable learning conditions. These estimates were based on increased productivity in adult life due to better exam grades in school, fewer pupils staying longer in elementary schools, resulting in overall shorter education periods, reducing the period for joining the job market, and reduced teacher sick leave.
Improving “sick building syndrome”
The term “sick building syndrome” is used to describe situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified.
Studies found that bad indoor air quality can decrease workspace productivity by more than 50 percent while increasing the average sickness absence rate by up to 52 percent.
Current norms and guidelines for the ventilation of educational buildings differ among countries and regions. In general, a minimum airflow rate per person and/or per floor area unit is required to dilute the air pollutant concentrations to a specific level of air quality. Usually, the ventilation rate is expressed in L/s (m3/h) per person or L/s (m3/h) per m2 floor area. However, these minimum requirements may not address specific occupancy types, levels of activity, or types of pollutants, leading to ventilation rates in classrooms that are often lower than the minimum ventilation rates specified in building codes and standards. Furthermore, the maximum concentration of CO2 in classrooms might vary by different standards, however, the upper threshold is about 1,000 ppm.
Ventilation systems can utilize natural ventilation, mechanical ventilation, or a hybrid of both. The key features of a ventilation system, as it relates to air quality, are sufficiently high air-change frequency and clean air supplied to the right places.
Natural ventilation eliminates costly mechanical equipment and ductwork from a project while also providing lower running costs. Building inhabitants enjoy the psychological benefits of contact with nature. By nature, however, natural ventilation is not controlled and therefore may not always be sufficient. Many locations, climates, and building types also create additional challenges to relying entirely on natural ventilation, primarily due to outdoor air and noise pollution and extreme indoor/outdoor temperature differences.
Natural ventilation is the most common type, predominant in the US, Southern, and South-Eastern Europe, China, India, Australia.
The UK has a significant percentage of schools naturally ventilated, the mechanical ventilation systems being present in approx. 12% of the buildings, while Canada is intensely investing in equipping all educational buildings with heating, ventilation, and air conditioning (HVAC) systems, given the recent pandemic concerns. The use of natural ventilation provides acceptable IAQ levels and reduces energy use given the consequent reduction in the use of mechanical ventilation therefore, most schools choose natural ventilation as the primary method for improving IAQ.
Window opening decreases the CO2 levels but increases the NO2 and SO2 levels.
In a mechanical ventilation system, either automatic or manual detectors may be utilized to determine when ventilation is needed in a space. Automated systems can be set to a timer or programmed to detect pollutants levels, such as CO2, and are the most efficient option. However, manual control can increase the occupants’ perception of comfort. Another important human factor in mechanical systems is maintenance and upkeep. Even the best-designed (and built) ventilation system will not function as intended if not regularly maintained, for example, if the air filters are not regularly changed.
Indoor air quality sensors like Senzemo’s Senspuck PURE measure both CO2 and VOC. This data then be used by AI to manage HVAC systems.
Many systems today incorporate both natural and mechanical ventilation aspects and are therefore considered hybrid systems. Systems like these hint at the directions that architects and designers can take to provide buildings with healthy air. The encompassing strategy and best practice to improve indoor air quality is to reduce pollution at its source while also improving ventilation and purifying the air. A solid starting point is to carefully specify non-polluting materials and equipment to eliminate VOCs as much as possible, yet various mitigating factors can make this impractical or even unfeasible.
The next step, then, is ventilation and ensuring an adequate number of air changes per hour are provided to accommodate the volume of space. The number of air changes will be affected by factors like occupancy and activity in the space. As this air comes into the building, it should be purified, filtering out particulate matter. This is the time at which human attention becomes especially important, as if these filters are not maintained often, they can themselves become a source of pollution.
Another strategy is to incorporate plants into a building design, such as through a green wall or an indoor planting area. Plants not only filter carbon dioxide and possibly some harmful chemicals out of the air, but the principles of biophilia posit that for humans to be in contact with nature increase mental and physical well-being. Plants alone, however, cannot solve a building’s air quality problems. Air-purifying building products can also improve IAQ by absorbing formaldehyde from the air.
New construction has the opportunity to design for good indoor air quality, but many older buildings, or simply those built without concern for IAQ, would also benefit immensely from retrofitting to improve the indoor environment.
We spend about 80% of our time indoors, making it worth the effort and investment to ensure the very air we breathe is not causing us harm.