One of Biden's first signed executive orders is telling. It discusses multiple ways to address air pollution, including reducing methane emissions in the oil and gas sector, establishing job-creating fuel economy standards, reducing air pollution from coal- and electric-fired utilities, and accounting for climate change.
However, "air pollution" in this context means outdoor air pollution, consistent with the EPA's regulatory powers under the Clean Air Act. The CAA authorized the development of comprehensive regulations to limit emissions from both stationary sources (e.g., industrial plants) and mobile sources (e.g., cars).
With few exceptions, the EPA does not directly regulate indoor air, and no federal agency has broad authority to regulate residential indoor air. However, comparative risk studies performed by the EPA's Science Advisory Board have consistently ranked indoor air pollution as one of the top five environmental risks to public health.
Post-pandemic trends, an aging population and the "aging in place" movement portend increased exposure to residential indoor air pollutants, and more risk for a growing vulnerable population. However, safe residential air poses unique challenges, defies traditional regulation and requires a fresh, multidisciplinary approach.
How Residential Indoor Air Poses Health Risks, Especially for Vulnerable People
Consider these key facts: 
- Americans, on average, have historically spent approximately 90% of their time indoors, where the concentrations of some pollutants are often two to five times higher than typical outdoor concentrations.
- People who are often most susceptible to the adverse effects of pollution — e.g., the very young, older adults, people with cardiovascular or respiratory disease — tend to spend even more time indoors.
- Indoor concentrations of some pollutants have increased in recent decades, due to such factors as energy-efficient building construction (which lacks sufficient mechanical ventilation to ensure adequate air exchange) and increased use of synthetic building materials, furnishings, personal care products, pesticides and household cleaners.
Typical indoor air pollutants include:
- Combustion byproducts such as carbon monoxide, nitrogen dioxide, particulate matter and environmental tobacco smoke;
- Substances of natural origin such as radon, pet dander and mold;
- Pesticides, lead and asbestos;
- Ozone from some air cleaners; and
- Various volatile organic compounds from a variety of products and materials.
Strategies for improving indoor air quality, including residential indoor air, involve: (1) controlling airborne pollutants; (2) introduction and distribution of adequate outdoor air; and (3) the maintenance of acceptable temperature and relative humidity.
Specific controls include venting indoor combustion sources like stoves and heaters, air filtration systems, proper home and HVAC system repair and operations, and reducing dust and allergens.
How Post-Pandemic Residential Air Pollution Poses More Potential Risk
With the pandemic, indoor air exposure increased. One striking, substantiating example was reduction of smog in California — i.e., less outdoor air pollution because people stayed indoors.
Of the 90% of estimated time spent normally indoors, a greater proportion of that time was spent in residences. Nonessential and vulnerable workers stayed home, and offices and schools closed. As of February, almost a year into the pandemic, 56% of U.S. workers continued to report working remotely from home all or part of the time.
With vaccination rates rising, Gallup has identified more people seeking a return to the office and less fear of COVID-19 risks. But 44% have also said, irrespective of COVID-19, that they want to continue remotely working because they prefer it. This suggests a more permanent shift to remote work.
Other key trends suggest risk. The U.S. population is aging, and there is a movement toward aging at home. Indoor air pollution is linked with poor respiratory health, and poor respiratory health enhances vulnerability, exacerbates symptoms and impacts the prognosis for various diseases.
Moreover, the elderly and other vulnerable groups face more challenges in addressing indoor air quality due to physical, financial and social factors preventing home maintenance or implementation of other controls. A significant percentage of the elderly population live on modest fixed incomes, and in older homes with dated appliances.
The Law's Failure To Comprehensively Address Indoor Air
Despite the potential health risks of indoor air pollutants, the EPA's enforcement essentially stops at our doorways.
This is not to say that there are not standards for levels of some commonly found indoor air pollutants, like carbon monoxide and nitrogen dioxide; many bodies have set standards and guidelines for both.
The EPA, the National Institute for Occupational Safety and Health, or NIOSH, and the Occupational Safety and Health Administration, or OSHA, have set carbon monoxide guidelines, but the EPA's guidelines only apply to outdoor air, and OSHA and NIOSH are concerned primarily with industrial work settings.
Other federal laws address specific pollutants or products. A nonexhaustive list includes the Toxic Substances Control Act, addressing radon and lead-based paint hazards; the Safe Drinking Water Act, addressing pollutants in drinking water that could impact residential air; the Federal Insecticide Fungicide and Rodenticide Act, addressing various pesticides; and the Consumer Product Safety Act, addressing chemicals in consumer products.
Recent Policy Targeting Aspects of Impact Indoor Air Quality
An emphasis on climate change means a focus on combustion sources, including those contributing to poor indoor air quality.
On April 2, 2020, the EPA finalized a rule reducing emissions from several wood-burning sources. The EPA's New Source Performance Standards for residential wood heaters fall under Section 111 of the Clean Air Act. The standards govern the manufacture and sale of new residential wood heating devices, and do not apply to existing wood stoves and other wood heaters installed in homes.
Up to 30 million people in the U.S. live in homes where wood burning is used for either primary or secondary heating. Indoor particulate matter from these sources can have health impacts, and those affected often come from more vulnerable populations — including the elderly in rural regions already facing high rates of chronic disease and limited health resources.
State and Local Law Developments
The Environmental Law Institute tracks state and local laws relating to indoor air quality. Below is a subset of recent measures that have implications in a residential setting.
Colorado amended its residential landlord-tenant law, H.B. 19-1170, to protect against mold and dampness conditions that "would materially interfere with the life, health, or safety of a tenant."
Within 96 hours of receiving notice of such conditions, a landlord must install a containment to stop active sources of water contributing to the mold, as well as install a high-efficiency particulate air filtration device. The law also requires certain remedial actions within a reasonable amount of time, and a comparable dwelling or hotel room for an impacted tenant upon request.
Connecticut enacted a law, P.A. 18-160, establishing a Healthy Homes Fund, in which the state Department of Housing funds a program "to reduce health and safety hazards in residential dwellings, including, but not limited to, lead, radon and other contaminants or conditions, through removal, remediation, abatement and other appropriate methods."
The Healthy Homes Fund is funded by remittances from a surcharge on homeowner's insurance policies, and took effect Jan. 1, 2019.
The California Energy Commission approved the state's 2019 Building Energy Efficiency Standards, to take effect Jan. 1, 2020. The standards are noteworthy for requiring that ventilation systems in both high-rise and low-rise residential buildings have air filters with a minimum MERV 13 efficiency rating.
New York City enacted the Asthma Free Housing Act, 2018/055, requiring that private landlords prevent and remediate indoor allergen hazards, including mold and pest infestation. The law also directs the city to incorporate mold and pest infestation in its housing code inspections, train enforcement staff, and establish procedures for implementing the law.
Insurance Implications of an Increased Focus on Indoor Air Pollution
New laws and standards raise insurance implications, especially as landlords face increased responsibilities.
Some courts interpret pollution exclusions as barring coverage for only those injuries allegedly caused by traditional environmental pollution as historically understood. Others interpret pollution exclusions as excluding coverage for all injuries caused by pollutants, claiming exclusions are unambiguous.
A case decided in 2014 by the Nevada Supreme Court, Century Surety v. Casino West Inc., is illustrative. In that case, carbon monoxide that killed four people sleeping above a pool heater in a hotel was held not to be a pollutant excluded by the pollution or indoor air quality exclusion clauses. The court emphasized the policyholder's realistic expectations about coverage, explaining that exclusion clauses arose out of "traditional environmental pollution."
Other insurance coverage cases also discuss "traditional environmental pollution," and jurisdictions have taken different approaches to carbon monoxide, lead paint, mold, etc. The increased importance of indoor air quality could lead to further litigation as indoor air quality is determined by many nontraditional pollutants.
Solutions Will Require Focus and Innovation
More environmental law or clearer insurance coverage rulings will not necessarily provide a complete answer.
Multiple sources, and the individual nature of residences and health status, pose challenges. The EPA and other agencies provide public information on self-help controls, but public accessibility is a question. The impact of educational materials or specific controls on reducing illness is also unknown.
There are questions whose answers could refine and prioritize solutions, including:
- What is the impact of indoor air contributors versus other sources or causes on health conditions?
- What are the most dangerous indoor sources, and are there ways to eliminate them or design them differently?
- What are the pros and cons of various air pollution controls?
- What is the public understanding of indoor air pollution and how can public education be designed and implemented effectively?
Law and evolving standards have a role to play. Improved product safety or venting requirements is one example. Many problematic sources could also be addressed through updated construction practices. Greater attention to residential exposure from outside environmental sources could also become a stronger part of industrial site cleanups or emission reduction plans already governed by federal and state environmental laws.
But the law could be a carrot as well as a stick. That is, it could incentivize helpful preventative measures.
Medical spending laws are one potential tool. Medicare constitutes a substantial part of the U.S. budget, with rising expenditures. As the population ages, promoting preventative care to mitigate the health and cost impacts of chronic disease will be critical. Prevention practices related to indoor air pollution could be part of a larger prevention strategy.
While the intricacies of Medicare reimbursement are beyond the scope of this piece, Medicare generally does not cover the cost of air purifiers, or other similar items such as room heaters, dehumidifiers or electric air cleaners. Some Medicare Advantage plans and other insurance plans have started recently covering air filtration equipment.
Medicare could encourage public health education through home health or virtual visits. Residential home assessment could be an important augmented service to home health care.
Technological solutions could also be transformative. And, given the post-pandemic growth in digital health, indoor air pollution solutions could be encouraged. Companies are working on filtration systems, real-time monitors, wearable devices and other related personalized devices.
Measurement and communication technology could also become part of a smart home system. There is room for creativity on solutions with varying price points.
Technology becomes especially important given the shortage of professionals to care for the elderly and homebound populations. Additionally, technological solutions could be more easily personalized to address specific risks and vulnerabilities.
Pandemics, an aging population and changing workplace dynamics all predict more indoor pollutant exposure. Knowledge, creativity, education and technology could intersect with law and policy to improve indoor air quality and health — but a multidisciplinary strategy is necessary.
Ann Al-Bahish is a partner at Haynes and Boone LLP.
The opinions expressed are those of the author(s) and do not necessarily reflect the views of the firm, its clients or Portfolio Media Inc., or any of its or their respective affiliates. This article is for general information purposes and is not intended to be and should not be taken as legal advice.
 Exec. Order No. 13,990, 86 Fed. Reg. 7057 (Jan. 20, 2021).
 42 U.S.C. §7401 et seq. (1970).
 Why Indoor Air Quality is Important to Schools, U.S. Environmental Protection Agency (March 25, 2021), https://www.epa.gov/iaq-schools/why-indoor-air-quality-important-schools.
 What are the trends in indoor air quality and their effects on human health, Report on the Environment, U.S. Environmental Protection Agency (March 25, 2021), https://EPA.gov/report-environment/indoor-air-quality (internal citations omitted).
 Julie Cart, As Californians stay at home, air quality improves — for now, CalMatters (April 12, 2020), https://calmatters.org/health/2020/04/as-californians-stay-at-home-air-quality-improves-for-now/.
 Lydia Saad and Adam Hickman, Majority of U.S. Workers Continue to Punch in Virtually, Gallup, Economy (Feb. 12, 2021), https://news.gallup.com/poll/329501/majority-workers-continue-punch-virtually.aspx.
 Demographers project that by 2040, the U.S. population aged 65 and older will double to 80 million, and their share of the total population will rise from 13% to 20%. Adele M. Hayutin, Miranda Dietz and Lillian Mitchell, 2010, New Realities of an Older America, Stanford Center on Longevity, 4–5. According to the Census Bureau, there were 40.3 million U.S. residents 65 and older in 2010 and more than 54 million on July 1, 2019. Older Population and Aging, U.S. Census Bureau (March 25, 2021), https://www.census.gov/topics/population/older-aging.html#:~:text=According%20to%20the%20U.S.%20Census,million%20on%20July%201%2C%202019.
 A 2010 AARP survey found that 88% of respondents over age 65 wanted to remain in their homes for as long as possible. Teresa A. Keenan, 2010, Home and Community Preferences of the 45+ Population, AARP Public Policy Institute, 4, 8. See also U.S. Department of Health and Human Services, National Institute on Aging, Aging in Place, Growing Older at Home (March 25, 2021), https://www.nia.nih.gov/health/aging-place-growing-older-home.
 Indoor air quality is not regulated under the Clean Air Act. The EPA does regulate outdoor sources of pollution that may infiltrate homes. For example, under the Superfund program, cleanups involving groundwater must address the vapor intrusion pathway. This is because chemicals in the groundwater below homes may, under some circumstances, infiltrate homes through pipes or foundations.
 Common sources include unvented kerosene and gas space heaters, leaking chimneys and furnaces, back-drafting from furnaces, gas water heaters, wood stoves and fireplaces, gas stoves, generators and other gasoline powered equipment, automobile exhaust from attached garages, and tobacco smoke.
 See https://www.epa.gov/residential-wood-heaters/final-2020-new-source-performance-standards-residential-wood-heaters.
 Curtis Noonan, Tony Ward and Erin O. Semmens. 2015. Estimating the number of vulnerable people in the U.S. exposed to residential wood smoke, Environ. Health Perspectives, 123(2).
 See https://www.eli.org/buildings/recent-developments-iaq.
 2019 Standards, Title 24 Cal. Code Regs., Part 6, Sections 120.1(b), 150.0(m). "MERV" stands for Minimum Efficiency Reporting Values and the values range between 1-16. The higher the number, the more particulate matter is filtered.
 Century Surety v. Casino West Inc. , 329 P.3d 614, 329 P.3d 614 (Nev. 2014).
 Several technological solutions address some of the common health problems the elderly face. For example, in Japan, a wearable device has been developed to monitor swallowing patterns to prevent choking. Robots help with aspects of isolation, and sensors and communications systems address fall risks. Other technologies provide medication reminders and health education. Safety, efficacy and privacy issues are important issues with these technologies. The same concerns would apply to air quality technology, and due diligence is appropriate.
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