In the 1970s, the United States successfully adopted a set of universal regulations for outdoor air quality. When it comes to indoor air quality (IAQ) standards, however, the federal government prefers to encourage rather than mandate. However, some experts are unsatisfied with this voluntary approach.
Led by Dr. Lidia Morawska of the International Laboratory for Air Quality and Health, 40 scientists from 15 countries jointly called for mandatory IAQ standards in the March issue of Science. Their paper — "Mandating indoor air quality for public buildings” — acknowledges the economic, political, and practical challenges of legislating indoor air quality standards, while also suggesting methods for overcoming these challenges. While the full text of the paper can be found here, we’ll save you the effort with the following interpretive summary. (Note that all quotes are from either the paper or its supplementary materials unless otherwise indicated).
Challenges
The challenges identified by the scientists can be split into 4 categories.
Challenge 1: People Are the Biggest Threat to Indoor Air Quality
“Most respiratory infections are acquired indoors, through inhalation of virus-laden airborne particles.”
The most important part of air quality is source control — that is — limiting or avoiding the generation of contaminants in the first place. However, one of those sources has a mind of its own; human beings release CO2 and infectious pathogens into the indoor air. In addition, outdoor CO2 levels are increasing rapidly due to global industry. Thus, limiting CO2 and pathogens via source control is extremely difficult.
Challenge 2: Some Pollutants Are Impractical to Monitor Indoors
“We cannot use the well-established approach that is used to measure outdoor air quality to monitor IAQ.”
“The World Health Organization (WHO) Global Air Quality Guidelines (AQG) published in 2021 provide recommendations for concentration levels of [6] pollutants and their averaging times (PM2.5, PM10, NO2, SO2, CO, and O3) and apply to both outdoor air and [indoor air].” However, NO2 (nitrogen dioxide) and O3 (ozone) lack reliable sensor technology; specifically, the presence of one can interfere with the accurate detection of the other. Meanwhile, SO2 (sulfur dioxide) is becoming less prevalent outdoors and has few indoor sources.
Contaminants outside of these 6 also have monitoring hiccups. According to the authors of the paper, “[a]t least [7] different definitions are known for the term TVOC (total volatile organic compounds) alone, based on different measurement and calculation procedures.” This is a problem for legislative standardization (but we still hold that it can be a useful metric individually). As for the stars of recent times — bacteria, fungi, and viruses — “there are no exposure-response relationships for respiratory pathogen concentrations in [indoor air], nor are there technologies available to routinely monitor such pathogens in buildings in real-time.” This is indeed true, though ActivePure is working on a solution.
Challenge 3: Someone Has to Actually Make (and Eat) the Sausage
“Laws, like sausages, cease to inspire respect in proportion as we know how they are made.”
The paper identifies several complications to creating a coherent IAQ law, many of which apply to the creation of any standards legislation. First, as we saw above with TVOCs, key definitions can vary between jurisdictions. Second, most countries wisely divide their governance between federal, state, and local levels — leaving open the question of who is responsible for enforcement. Third, “[i]t is conceptually difficult to legislate for air quality standards in general, let alone IAQ, because air quality legislation is typically focused on a result or outcome, rather than on behavior.”
Finally, enforcement requires frequent measurements in each and every regulated building, “because every space is different and is used differently.” On a practical level, this rules out ongoing enforcement in private homes and makes enforcement of businesses very difficult. Schools and hospitals, however, might be more amenable to such required compliance.
Challenge 4: Different Stakeholders Have Different Priorities
“[...]establishing an IAQ standard is always the result of a compromise between scientific knowledge and political will.”
As a final challenge, the authors of the paper admit that “[t]here will always be some industries that do not benefit and/or will require strategic change owing to new regulations, so they would prefer the status quo.” For instance, HVAC professionals are often focused on energy efficiency and comfort; changing that paradigm to include airborne contaminants will require significant capital investment. If the customer demand doesn’t justify it, they may ask, why should the legislation mandate it?
Solutions
The paper proposes several solutions to these challenges to overcome the reluctance of industry and law.
Solution 1: Get Creative About Balancing Ventilation and Energy Efficiency
“Several means are available for achieving IAQ that meets these objectives.”
There is more than one way to increase ventilation. Setups such as demand control ventilation, enthalpy recovery vehicles, and stratified air supplies can all assist an HVAC technician in increasing air changes per hour(ACH) while minimally increasing energy costs. Ventilation can also be flexibly adjusted based on occupancy and seasonal pathogen risk (i.e. flu season). However, the best tool (as far as we are concerned) is supplementary air purification. Assistance from air cleaners and filters can take some of the burden off ventilation while reducing contaminants.
Solution 2: Use Affordable, Existing Monitors for Select Proxy Pollutants
“Standards must establish specifications for IAQ and be technically feasible, affordable to construct and operate, and compatible with other priorities and constraints such as energy use.”
To minimize stakeholder expense, the paper advocates monitors that are already widely available (and often already widely installed) to monitor PM2.5, CO, CO2, and ACH. CO2 can act as a proxy for ventilation; if it is significantly higher than outdoor levels, “ventilation is inadequate.”
Of course, if the legislation isn’t specific, it won’t be enforceable. As you can see in the chart above, the authors of the paper propose specific levels for the 4 aforementioned factors. Some of these are above and beyond the currently recommended levels. For instance, the PM2.5 rate considers exposure over 1 hour rather than the 24 hours recommended by the WHO. The higher ventilation rate derives from the study of a classroom with an infectious student. However, the scientists acknowledge that “[s]uch an increment in the ventilation rate is not normally feasible in existing buildings.” Thus, the aforementioned need for supplementary air purification.
The paper notes that monitors for relative humidity can be a proxy for mold and allergens since “many species of bacteria and fungi, especially filamentous fungi (mold), grow indoors under moist conditions.”
Solution 3: Work with What You Already Have
“[...]if some countries lead by example, we anticipate that IAQ standards will increasingly become normalized.”
The scientists acknowledge that these specific numbers might not work for all buildings or all jurisdictions, but they do suggest drawing upon some existing “international scientific standard” to make things easier. Such standards could include ASHRAE 241 or the aforementioned WHO guidance.
Following this thought to its logical conclusion, the authors note that “[i]t is possible that IAQ could be addressed by including it within existing laws, for example, by amending existing public health legislation or environmental protection legislation to include provisions that expressly address IAQ.” In other words, lawmakers don’t have to reinvent the wheel.
As for the scope of these standards, the authors recommend focusing on regular measurement of public spaces such as schools, hospitals, and workplaces. The onus of enforcement would be on the property owners themselves. “Although enforcement of IAQ performance standards in homes is not possible, homes must be designed and equipped so that they could meet the standards.”
Solution: 4: Educate Stakeholders about the Benefits of Good IAQ
“Social and economic benefits in terms of public health, well-being, and productivity and performance will likely far outweigh the investment costs in achieving clean [indoor air].”
While IAQ improvements have short-term costs, they do have a long-term ROI. The authors note that disability-adjusted life years from indoor air pollution cost China the equivalent of 3.45% of its GDP between 2000 and 2017.
An earlier and similar letter signed by 6 former Surgeon Generals highlights the potential benefits of revising building policies to focus on IAQ:
- “A potential $200 billion annual productivity gain corresponding to a 20% to 50% reduction in Sick Building Syndrome symptoms for office workers in the U.S.”
- “An estimated $38 billion in annual economic benefits from increasing minimum ventilation rates in U.S. offices.”
- “A return of $3.48 for every dollar companies spend on workplace wellness programs due to reduced medical costs, and an additional return of $5.82 due to reduced absenteeism.”
- “An up-to-101% improvement in cognitive function, supporting employee productivity benefits up to $7,500 per person per year.”
If stakeholders know about benefits like these, they may not balk at the initial cost.
Conclusion
While ActivePure remains politically neutral as to the legislation vs. voluntary standards, we do predict that mandatory IAQ legislation will come along eventually. By taking initiative now, businesses and individuals can get ahead. Take a look at where we think IAQ standards should head in our open letter to the EPA.
