Air Pollutants: Understanding The Threat

Air pollution is a pressing issue that poses significant risks to human health and the environment. It refers to the contamination of indoor or outdoor environments by chemical, physical, or biological agents that alter the natural composition of the atmosphere. These pollutants come from various sources, including household combustion devices, motor vehicles, industrial facilities, and forest fires. The criteria air pollutants, as classified by the EPA, include ground-level ozone, particle pollution, carbon monoxide, lead, nitrogen oxides, and sulfur oxides. Hazardous air pollutants, or HAPs, are chemical compounds suspected of causing cancer and other severe health issues. The presence of these pollutants in the air has led to an increase in respiratory diseases and other adverse health effects, with vulnerable populations such as children, older adults, and people with pre-existing respiratory conditions being at higher risk. Addressing air pollution is crucial to mitigate its impact on public health and the environment.

Criteria pollutants

Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. Common sources of air pollution include household combustion devices, motor vehicles, industrial facilities, and forest fires.

The six criteria air pollutants, as defined by the EPA, are ground-level ozone, particle pollution (particulate matter), carbon monoxide, lead, nitrogen oxides, and sulfur oxides. These pollutants are regulated by the EPA using human health-based and environmentally based criteria.

Particulate matter, or particle pollution, refers to tiny pieces of solids or liquids in the air. These particles can be large enough and dark enough to be visible, like smoke, or so small that they are invisible. Particle pollution can irritate the eyes, nose, and throat, and smaller particles can enter the deep parts of the lungs or even the bloodstream. Sources of particle pollution include dust from roads, farms, dry riverbeds, construction sites, and mines.

Carbon monoxide (CO) is a colorless, odorless gas that can be released during the incomplete combustion of fossil fuels in boilers and engines, but it is primarily produced by automobiles, trucks, and buses. CO can be found in higher concentrations in areas with poor ventilation, such as parking garages, tunnels, or areas with high traffic congestion.

Nitrogen oxides and sulfur oxides are gaseous pollutants that can have harmful effects on human health and the environment. Elevated concentrations of sulfur oxides, in particular, can react with other compounds to form small particles that contribute to particulate matter pollution and can harm trees and plants by causing acid rain.

Ground-level ozone is another criteria pollutant that, along with particle pollution, poses a threat to air quality and public health. Ozone is one of the criteria pollutants for which certain states, including New Hampshire, must submit State Implementation Plans (SIPs) regardless of their attainment status.

Hazardous air pollutants (HAPs)

Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. Air pollutants can be categorised as common or criteria pollutants, and hazardous air pollutants (HAPs).

HAPs are pollutants known to cause or reasonably anticipated to cause adverse effects on human health or the environment. They are known to cause cancer and other serious health issues, such as reproductive problems, birth defects, and respiratory issues. The Clean Air Act, amended in 1990, originally identified 189 HAPs for regulation, and this list is modified through rulemaking. As of 2022, there are 188 federally regulated HAPs. HAPs may be emitted from stationary sources (industrial processes) or mobile sources (vehicles). They are regulated by specified controls known as Maximum Achievable Control Technology standards (MACTs) and Generally Achievable Control Technology standards (GACTs). These standards apply to industrial and area source categories, such as paper mills and fuel combustion sources.

The US Environmental Protection Agency (EPA) develops regulatory programs and national enforcement initiatives to limit emissions from stationary sources and address significant environmental risks. EPA inspections include inspecting processes with emissions points and wastewater discharges, as well as design and work practice standards. The National Emission Standards for Hazardous Air Pollutants (NESHAP) are stationary source standards for HAPs.

The major sources of outdoor air pollution include residential energy use for cooking and heating, vehicles, power generation, agriculture/waste incineration, and industry. Household combustion devices, motor vehicles, industrial facilities, and forest fires are common sources of air pollution. Fine particulate matter in the air, resulting from both ambient and household pollution, leads to strokes, heart disease, lung cancer, and acute and chronic respiratory diseases. Approximately 2.4 billion people are exposed to dangerous levels of household air pollution, primarily from open fires or simple stoves for cooking fuelled by biomass or coal.

The World Health Organization (WHO) promotes interventions and initiatives for healthy sectoral policies and provides technical support to its member states. WHO also monitors and reports on global trends and changes in health outcomes associated with actions taken to address air pollution.

Particulate matter

Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. One of the major pollutants of public health concern is particulate matter.

The inhalation of particulate matter has been linked to a range of adverse health effects. These include respiratory diseases, cardiovascular disease, lung cancer, asthma, developmental disorders, neurodegenerative disorders, mental disorders, and premature death. Outdoor fine particulates with diameters less than 2.5 microns are responsible for 4.2 million annual deaths worldwide and are the fifth-leading risk factor for death. Long-term exposure to PM2.5 has been associated with an increased risk of heart attacks and vascular inflammation due to high plaque deposits in arteries.

Outdoor air pollution

Particulate matter (PM), a common proxy indicator for air pollution, is made up of tiny pieces of solids or liquids in the air, such as smoke, dust, sulfates, nitrates, and black carbon. PM can irritate the eyes, nose, and throat, and smaller particles can penetrate deep into the lungs and even enter the bloodstream.

Other outdoor air pollutants include ground-level ozone, carbon monoxide, nitrogen oxides, and sulfur oxides. These pollutants are regulated by organizations like the EPA and WHO, which have implemented standards and initiatives to improve air quality and protect public health.

The effects of outdoor air pollution are far-reaching, with 4.2 million premature deaths worldwide in 2019 attributed to ambient (outdoor) air pollution. People in low- and middle-income countries are disproportionately affected, with 89% of premature deaths occurring in these regions. The highest number of premature deaths were in the WHO South-East Asia and Western Pacific Regions.

To mitigate outdoor air pollution, policies and investments that support cleaner transport, energy-efficient homes, improved waste management, and cleaner industrial technologies are crucial. These measures can effectively reduce key sources of outdoor air pollution and protect the health of people around the globe.

Indoor air pollution

Air pollution is defined as the contamination of the indoor or outdoor environment by any chemical, physical, or biological agent that modifies the natural characteristics of the atmosphere. Indoor air pollution, also known as Indoor Air Quality (IAQ), specifically refers to the air quality within and around buildings and structures and its impact on the health and comfort of the occupants.

Sources of indoor air pollution are varied and include building materials, household cleaners, and biological pollutants such as dust mites and pet dander. Inadequate ventilation can exacerbate indoor pollution by not adequately diluting emissions from indoor sources and by failing to remove pollutants from the indoor space. High temperatures and humidity levels can also increase indoor pollutant concentrations.

The health effects of indoor air pollutants can be felt immediately or years after exposure. Immediate symptoms include irritation of the eyes, nose, and throat, headaches, dizziness, and fatigue. These effects are usually short-term and treatable, and removing the person from the source of pollution can alleviate symptoms. However, pollutants commonly found in indoor air can also cause more severe and long-term health issues, including respiratory diseases, heart disease, and cancer.

The World Health Organization (WHO) has issued guidelines to address household air pollution, providing recommendations on the types of fuels and technologies that can protect health, such as solar, electricity, biogas, liquefied petroleum gas (LPG), and natural gas. These guidelines aim to reduce the negative health impacts of indoor air pollution, which is responsible for millions of premature deaths annually.

Overall, understanding and controlling common indoor pollutants are crucial to reducing the risk of adverse health effects. Improving indoor ventilation and air quality can help mitigate the impact of indoor air pollution on human health.

Frequently asked questions