Did you know? Radon is the leading cause of lung cancer among nonsmokers. Common indoor asthma triggers include mold, dust mites, secondhand smoke, and pet hair. Between , and 1,, children with asthma have their condition made worse by exposure to secondhand smoke each year. Common indoor air pollutants and their sources include: Fireplaces, space heaters, and wood and gas stoves emit carbon monoxide CO and nitrogen dioxide NO 2 , Air fresheners, paints, cleaning supplies, and furniture emit volatile organic compounds VOCs , Radon contaminated soil and water emit radon, Increased humidity, leaks, and excess moisture promote mold growth, Pillows, blankets, and stuffed animals host dust mites, Cigarettes emit secondhand smoke, and Cats and dogs shed pet dander.
Improve Indoor Air Quality Steps you can take to maintain healthy indoor air quality include improving ventilation, controlling moisture levels, reducing pollutants, and increasing energy efficiency.
Reduce exposure to asthma triggers by learning how to discover them. A shift away from the use of petroleum as a transportation fuel would have important benefits for reducing ambient particle concentrations. Because of the close proximity between urban roadways and buildings, tailpipe emissions from vehicles have a higher effectiveness in causing indoor air pollutant exposure per unit mass emitted than do central-station power plants, which emit their pollutants from tall stacks, often on the edge of or remote to populous regions. As with coal-fired electricity, an effective response to climate change in the transportation sector might yield some co-benefits in reducing indoor exposure to particulate matter.
For example, a shift from vehicles powered by internal combustion engines to plug-in hybrid vehicles, to electric vehicles, or to fuel-cell-powered vehicles could lead to a significant net reduction in outdoor particle levels near buildings and consequent improvements in indoor air quality. Climate-change concerns may encourage increased use of wood combustion and the burning of other contemporary-carbon fuels for home heating. Climate change is expected to increase the frequency of wildfires. Higher ambient temperatures combined with episodes of drought could lead to periods with a higher tendency for forests to burn.
Since wood smoke particles are primarily in the fine mode, ordinary indoor environments, especially residences, do not provide much protection. Another expected effect of climate change is increased prevalence of drought, both in time and space. It is also anticipated that water resources will become further strained, which may lead to various pressures that could increase the dryness of land surfaces, such as reduced irrigation of crops and declining reservoir or lake levels owing to increased water extractions or diversions of influent streams.
These conditions would have a tendency to increase the emissions of windblown dust into the atmosphere. Results from several recent studies illustrate the nature of the concern. Kuo and Shen reported increased levels of indoor PM 2. Their results demonstrated 'associations between several measures of particulate matter and daily mortality in an environment in which particulate concentrations are dominated by the coarse fraction'.
Malig and Ostro assessed mortality statistics from 15 California counties for — in relation to coarse particle monitoring data. They found 'evidence of an association between acute exposure to coarse particles and mortality', and that 'lower socioeconomic status groups may be more susceptible to its effects'. With regard to the indoor proportion of outdoor particles, future conditions might be substantially different than current conditions in the building stock.
However, the body of evidence is weak for making predictions about the nature and scope of change to be expected. The basis is even weaker for specifically attributing a portion of whatever evolution occurs to climate change. What is known for US conditions can be summarized as follows. Traditionally, open windows have made important contributions to residential ventilation, so simply having a tighter envelope does not necessarily translate to lower air-exchange rates. Lower air-exchange rates would tend to provide improved protection for building occupants against particles of outdoor origin.
However, with lower air-exchange rates, concentrations of pollutants from indoor sources would tend to rise. Mechanical systems that provide supply air can be equipped with filters to remove particles. So, further technological innovation and system improvements might be necessary to achieve economical yet reliable, and durable high-performance mechanical ventilation systems in residences that provide good protection for occupants against particles of outdoor origin.
Ozone is a secondary atmospheric pollutant, formed by photochemical reactions involving nitrogen oxides and volatile organic compounds. Ozone concentrations in urban air have declined slowly over time in urban areas of the United States, resisting relatively vigorous efforts at controlling precursor emissions. As health science information has improved, the air quality standard for ozone has become progressively more stringent.
Over time, the background level of ozone in the clean troposphere has risen Vingarzan Consequently, the gap between baseline ozone levels in the absence of anthropogenic precursor emissions and allowed concentrations under the NAAQS has narrowed. Several modeling studies have explored the consequences of climate change for outdoor ozone concentrations.
They found that, 'impacts of global climate change alone on regional air quality are small compared to impacts from emission control-related reductions'. They also predict that mean annual PM 2.
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Racheria and Adams published an analogous study in which they concluded that, 'climate change, by itself, significantly worsens the severity and frequency of high O 3 events over most locations in the US, with relatively small changes in average O 3 air quality'. Buildings offer some protection from ozone exposure because ozone irreversibly decomposes on indoor surfaces and also reacts with some gas-phase species that may be found indoors.
However, some ozone that penetrates does persist. New evidence from research on ozone-initiated chemistry raises a potentially important question: to what extent are the health risks that are ascribed to ozone exposure influenced by the coincident exposure to the products of ozone-initiated chemistry? The distinction is important in the context of considering climate-change impacts on indoor air quality and health. Such changes might deliberately or inadvertently alter the indoor to outdoor relationship for ozone, e.
Such changes could also deliberately or inadvertently alter the nature, degree, and significance of ozone-initiated indoor chemistry. These two considerations overlap but are not coincident. Overall, if ambient ozone levels increase while ventilation rates decrease, the net effect on indoor ozone concentrations is uncertain, but one would expect higher indoor concentrations of the byproducts of ozone-initiated chemistry.
Pollen levels in outdoor air might rise as a consequence of climate change Reid and Gamble Allergic rhinitis is a common malady. As such, they should neither effectively penetrate into nor persist in indoor air Liu and Nazaroff , Sippola and Nazaroff , Nazaroff Consideration of these factors would suggest that buildings would provide good protection against whole pollen grains and also that the biological insult associated with exposure to whole grains should be concentrated in the extrathoracic regions eyes, nose, throat.
The tracking of pollen grains into buildings e. Furthermore and perhaps more importantly , pollen grains can fracture, generating much smaller particles 0. These smaller particles could penetrate both the building envelope and the upper respiratory tract. Ambient SO 2 levels are primarily a result of coal combustion and originate from the presence of sulfur as a percent-scale impurity in coal. Ambient air quality standards for SO 2 , as well as acid-rain legislation i. The largest remaining emissions are from older power plants whose high emission rates continue to be allowed.
New coal-fired power plants are required to have good emission controls for SO 2 that are achieved, for example, using flue-gas desulfurization. If the use of coal to provide electricity and potentially for liquid fuels continues into the future without regard for climate, then ambient SO 2 levels might rise. However, an alternative possibility is that—to the extent that coal use for energy continues—it will be done in a manner that exhibits improved emission controls such that SO 2 emissions would decline.
Nitrogen oxides mainly NO and NO 2 are emitted primarily as a result of combustion processes. To some extent, the presence of N in fuel as in coal leads to NO x emissions. However, any high-temperature combustion process that uses air as the oxidizer can also produce NO x emissions, with the N originating from N 2 in the combustion air. Important sources of NO x in ambient air are mobile sources both on road and off-road , fossil-fueled power plants coal and natural gas , and other stationary combustion of mainly fossil fuels.
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Because NO x is a precursor to ozone and other photochemical smog components, it has been and continues to be subjected to strong emission-control efforts, and continuing progress in reducing emissions can be anticipated for the near future. However, less future reliance on fossil fuels in particular and combustion in general suggests that NO x emissions may eventually decrease in a future climate-change regime.
In contrast to the criteria pollutants, HAPs are regulated only in terms of emission limits from major sources—there are no ambient concentration standards.
Concentrations of these pollutants are not routinely monitored. However, summary appraisals have combined emissions data with dispersion modeling and risk factors to discern which pollutants and where the health risks from HAPs are highest. The indoor proportion of outdoor pollutants has not been well studied for these pollutants, although for benzene and for the chlorinated organics it is reasonable to expect that indoor environments provide little or no protection from outdoor levels. Future trends in the outdoor concentrations of these pollutants in a climate-change regime are not clear, although the scrutiny that they are receiving as HAPs suggests that emissions might decline over time.
Conceptually, the nexus of climate change, indoor air quality, and public health is simple. A balance between sources and removal processes governs indoor air pollutant concentrations for any species in the air of any indoor space. Concentrations in combination with human occupancy govern exposures. Excessive exposures confer health risks to those exposed. Climate change can affect this system in numerous particular ways, many of which have been reviewed in this letter.
Climate Change, Indoor Environment and Health
For example, by causing an increase in the outdoor concentrations of certain pollutants at certain places and at certain times, indoor concentrations and associated exposures in buildings at those places and times would increase. Perhaps more important than the direct shifts caused by climate change are the shifts that are mediated by human responses to climate change. For example, mitigation measures to reduce energy use in buildings might lead to systematically lower ventilation rates in buildings that would cause higher concentrations and exposures to pollutants emitted from indoor sources.
An adaptation measure might be the increased use of air conditioning, which could exacerbate anthropogenic emissions of greenhouse gases and, if accompanied by reduced ventilation rates, increase the concentrations of pollutants emitted from indoor sources. Reactions to climate emergencies also pose certain public health risks, such as the potential for poisoning from exposure to carbon monoxide emitted from portable electricity generators.
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Dissected into its component parts, the elements of this system are indeed relatively simple. However, the elements that influence important outcomes in this system are numerous and diverse. Furthermore, these elements are interconnected in a complex manner that includes feedback loops and also interweaves natural processes with technology, individual human behavior, and social systems.
It is these systemic features, rather than the nature of individual elements themselves, that pose the greatest challenges for understanding and effectively addressing the impact of climate change on indoor air quality and public health. Because our overall understanding of this system is, as yet, limited, this article has focused on the factors that influence the indoor concentrations of health-relevant pollutants and how the concentrations might shift as a consequence of climate change.
Three classes of factors were identified as having important influence: pollutant attributes, building characteristics, and human behavior. The diversity of building types is important, since issues of concern and appropriate responses differ among single-family dwellings, multifamily apartment buildings, schools, health care facilities, offices, and so on.
It is also important to recognize and account for the diversity in subpopulations, in part because of variability in the degrees of susceptibility among individuals and groups to the effects of indoor air pollutant exposure. Furthermore, it is important to take account of variability within populations in the knowledge and resources with which to take effective action in response to changing conditions.
Actions taken by individuals can profoundly influence indoor air quality in individual buildings. In this respect, the system of indoor air quality and public health in buildings exhibits similarities with the safety aspects of the transportation system. In both cases, there are public as well as individual interests in seeing that the system works well, and negligent or ill-informed behavior by individuals can cause serious harm.
Focusing on pollutants, indoor concentrations can be decomposed into contributions from indoor sources and from outdoor air. Combustion is a major source of both outdoor and indoor air pollution and arguably produces the most important indoor air pollutants with respect to health risks. Important combustion-related issues associated with indoor emissions include carbon monoxide exposures from portable generator use and indoor air quality problems associated with cooking, heating, and smoking.
Other important pollutants associated primarily with indoor sources include radon and volatile and semivolatile organic compounds. Outdoors, the main pollutants of concern are particulate matter and ozone.