Premium
Four principles for achieving good indoor air quality
Author(s) -
Nazaroff William W
Publication year - 2013
Publication title -
indoor air
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.387
H-Index - 99
eISSN - 1600-0668
pISSN - 0905-6947
DOI - 10.1111/ina.12062
Subject(s) - avogadro constant , ideal gas law , ideal (ethics) , simple (philosophy) , kinetic energy , volume (thermodynamics) , einstein , order (exchange) , physics , atmosphere (unit) , ideal gas , law , meteorology , environmental science , thermodynamics , quantum mechanics , philosophy , epistemology , finance , political science , economics
Great scientific achievements are often expressed in simple terms. Consider Newton’s second law: force equals mass times acceleration. Or the first law of thermodynamics: energy is conserved. Or Einstein’s equation describing the interdependence of energy and matter: E = mc. These truths bring light to darkness and allow us to see order in what otherwise appears chaotic. Among my favorite examples is the ideal gas law: PV = nRT. Consider an ordinary room, with a volume of 50 m, an air temperature of 293 K, and a pressure of 1 atmosphere. From the ideal gas law, we know that the room contains 2080 moles of air. Furthermore, because the molecular weight of air is 29 g/mol, we also know that the room contains 60 kg of air. From Avogadro’s number, we understand that the room’s air comprises 1.25 9 10 molecules, a stunningly large number. From the kinetic theory of gases, we know that the molecules are traveling at a mean speed of 460 m/s and that they travel an average distance of 0.065 lm before colliding with another molecule. From these last two points, we infer that the average travel time between collisions is a mere 0.14 ns. Overall, each of the 10 molecules in the room experiences an average of 70 billion collisions per second with other molecules. And yet, PV = nRT. Order out of chaos! I have been wondering whether our community— those concerned with indoor environmental quality and health—knows enough now to articulate simple rules for achieving good indoor air quality. Such rules should not be expected to be as universally true as are laws in the physical sciences. Key tests of their value might be these. Are they easily understood? Are they mostly true? (And when not beneficial, are they also not harmful?) Do they help guide research and practice? It seems that we do indeed know enough to articulate a concise set of principles for achieving good indoor air quality. Here is a trial set: four ideas expressed in twelve words, listed in priority order. • Minimize indoor emissions. • Keep it dry. • Ventilate well. • Protect against outdoor pollution. The following paragraphs elaborate on the broader intent behind these concise statements. A brief critique is provided, stating some recognized limitations. Also, a few thoughts are expressed about ongoing research needs so that these rules can be more widely understood and more effectively practiced. A caveat: these guidelines focus on indoor air quality, a subset of indoor environmental quality. Other important issues are not addressed in these principles, such as maintaining thermal comfort and limiting noise pollution.