Ever since man first lit fires in shelters, indoor air quality has been a health issue. Evidence of such has been found in the the blackened lungs of mummified human remains discovered in Egypt, Peru and Great Britain. Millennia later, and we are still dying of poor indoor air quality – 3.8 million a year according to the World Health Organization- despite our scientific knowledge and technological advances.
Our first primitive homes usually had a central fire, where burning of the common fuels of the times – wood, animal dung and crop residues – provided warmth and cooking. At its worst, air pollution indoors can be 100 times worse than in the open air and to escape the detrimental effects of the smoke, attempts were made to ventilate these shelters. This was usually done by making a central roof opening.
In later dwellings, when thatch was used the central fire actually had some advantages. The smoke would gradually filter through the thatch and fire sparks could be smothered. Bugs living in the thatch were killed, the smoke played a role in waterproofing the thatch, and importantly, meat left in the ceiling could be smoked. Those multitasking fires were certainly useful!
Having said that, throughout history man has understood the general hypothesis that bad air is harmful to health. In the classical writings of the Romans there are references to ‘clouds of ashes’ and ‘poisonous fumes’ of the city of Rome and there is evidence that in the Roman civil courts actions were taken against certain residents for contaminating indoor air. A cheese-maker, for instance, is seen to get into trouble for polluting the building above it.
The noxious air in Rome was a problem despite the fact that the civilized Romans actually had pretty sophisticated methods of under floor heating without having to have an open fire in each room. These impressive heating systems were unfortunately a luxury reserved for the rich and the common man had to make do with open fires.
A welcome advance to improve indoor air quality was the invention of the chimney in the 15th century, although it took 200 years to be widely adopted. With the Norman invasion (1066), two-storey houses became fashionable and this meant a central fire was no longer possible, so the fire was moved to a niche in the wall. Over time, this design went from a hole into the exterior wall, to the creation of flues and eventually stone hoods and chimney caps to improve ventilation. But it wasn’t until timber supplies fell and the general population began to use coal, that the chimney became widely used – really out of necessity, as the fumes produced by coal were so toxic.
In the 1600s it was discovered that the supply of air to the lungs was essential for life. By the 1700s, it was common knowledge that expired air was unfit for breathing until it was refreshed, but it wasn’t until the 1800s and the hygiene revolution that it became known that humans needed a certain amount of ventilation to stay well. The first measurements and estimates of just how much turned out to be way below what we know today, but nonetheless, progress was being made.
Florence Nightingale has been referred throughout history as ‘the lady with the lamp’, but she was far more than this. Her handbook of modern nursing shows an advanced understanding of the importance of indoor air quality for human health and indeed the whole first chapter focuses on ventilation. Her time working as a nurse during the Crimean War in horrendous conditions convinced her that fresh air and cleanliness were paramount to recovery. She recommended opening windows where possible and the use of mechanical forced air if this wasn’t feasible. Realizing that up to 80% of British deaths that occurred in the Crimean War were due to the poor conditions in the army infirmaries, she recommended to the British government that better conditions would improve mortality. Not long after, a specially built hospital that had roof ridge tile ventilation and a forced air system was built on the banks of the Dardanelles. It was the first hospital built with ventilation as a priority.
Industrialization resulted in extensive use of coal and it was this and the coal smoke emitted from household chimneys that was responsible for the Great London Smog in the winter of 1952, a week long episode that was responsible for the deaths of thousands. The UK Clean air act of 1956 was passed as a direct result and triggered the banning of the domestic use of coal in many cities. Similarly, in the US the 1963 Clean Air Act was prompted by an episode in Pennsylvania when the river town of Donora was covered in a thick smog – 20 died and 6000 were sickened.
Meanwhile, little was being done regarding indoor air. Legislation for outdoor air was a no brainer as the toxic air could be seen, smelt and tasted, but less so indoors. In the 1900s generally it was felt that ventilation was a matter of comfort rather than health. In fact, the first electrical air conditioning system was used for economic reasons rather than health reasons.
In 1902, a printing plant in Brooklyn, New York, was experiencing difficulty in producing its magazine due to the intense humidity. The paper was absorbing moisture from the air and expanding, meaning the colours wouldn’t line up properly. Not only that, but the ink wouldn’t dry and the magazine was missing deadlines. A graduate of Cornell University, a Mr. Willis H. Carrier, had recently invented a machine that could control temperature, humidity, air circulation and ventilation and installation of it in the Brooklyn plant was transformative. Not long after, the New York Stock Exchange became the first building to install air conditioning simply for occupants’ comfort, with a system designed by another New York native, Alfred Wolff.
Air conditioning may improve the regulation of heat and thus vastly improve comfort but to improve health it must be combined with air filters so that polluted outdoor air isn’t just being circulated around the building. After all, indoor air will contain whatever is in the outdoor air plus all the contaminants produced inside. It was soon realized that improving comfort wasn’t enough. Florence Nightingale was right – poor air causes poor health.
And so, let’s move on to current times. One would think that man would have advanced to such a stage that the indoor air quality problems encountered in our first man-made shelters would be well and truly solved. Unfortunately, poverty dictates that millions of people in the developing world suffer from lung diseases and early mortality due to the burning of open fires to heat their homes and cook their food. It is responsible for a shocking 2 million deaths a year.
In the developed world, poor indoor air quality is a main cause of allergies, asthma, other hypersensitivity disorders, airway infections and cancers. The cause today is no longer the open fire but a complex combination of mainly man-made sources. Cancer is caused by radon, asbestos and, a major one until recent times and tighter regulations – cigarette smoke. Thankfully, asbestos is generally now only a problem in demolition and renovation. Lead paints used in the past can cause severe brain damage, especially in children.
Volatile organic compounds (VOCs) released from insulation, paints, carpets, glue, furniture, cleaning products and plywood can trigger asthma and allergies and a host of other health issues.
Particulate matter, both fine and ultrafine, is produced when cooking and without an efficient exhaust hood these particles make their way into our lungs and even into our bloodstream. According to a recent article in the New Yorker magazine, an ongoing study is suggesting that cooking a simple stir-fry on a gas burner can result in seriously dangerous levels of particulate matter. The study, which is being carried out at the University of Texas, showed that the cooking of a Thanksgiving dinner produced pollution that briefly exceeded that of Delhi, the worlds most polluted city.
Biological contaminants in our homes and offices include viruses, fungi, pollen, dander and mites. Légionnaire’s disease is caused by bacteria flourishing in inadequate air conditioning systems. Poor ventilation and overcrowded spaces can cause increased carbon dioxide leading to drowsiness, headaches and irritability. Mould from high humidity and water leaks can cause lung disease. Modern indoor air can certainly be complicated.
In the 1970s, energy conservation in large buildings became the norm and this meant reducing the exchange between indoor air and outdoor air, resulting in increased carbon dioxide, biological contaminants and VOCs indoors. A new phenomenon had been inadvertently created. The term ‘sick building syndrome’ was subsequently coined in 1986 by the WHO when they estimated that up to 30% of newly built office buildings in the west had indoor air problems. Talk about solving one problem only to produce another. Energy may have been conserved, but people were getting sicker.
The word ventilation comes from the Latin word ventilare meaning ‘expose to the wind’. If only it was so simple. Our polluted outdoor air and modern city living means that for the vast majority of us exposure to the wind is no longer the solution. But a solution is needed. It’s needed for the 3.8 million of us dying prematurely. Our indoor air may not be so visibly polluted as the yellowish-brown smog so thick that Londoners could not see their feet in 1952, but we still need to take serious action. Guidelines do exist, various parameters have been drawn up, studies and recommendations have been published. It’s a start but our indoor air – the air we breathe for up to 90% of the time – should be a priority.
The asthma & allergy friendly® Certification Program
About Dr. Anna O’Donovan – Medical & Lifestyle Author
Anna is a mum of three children, one with allergies, and she suffers from allergies and asthma herself. She is a qualified doctor and worked as a General Practitioner and as a dentist for a number of years. She is also an award-winning author.
Indoor air quality, air conditioning, air filters, air pollution, asthma and allergies, ventilation, lunghealth.
References and further reading
On the history of indoor environment and it’s relation to health and wellbeing, Click here.
Indoor air pollution: a global health concern, Click here.
On the history of indoor air quality and health, Click here.
Air Pollution Goes Back Way Further Than You Think, Click here.
Indoor air pollution major risk to health, The Irish Times, Click here.
The hidden air pollution inside your workplace, BBC, Click here.
Good Air and Bad Air: The Importance of Ventilation, Museum of Healthcare, Click here.
The hidden air pollution in our homes, The New Yorker, Click here.
Related Internal Links