Air Pollutants: What Else Is Harming Our Air?

Air pollution is a pressing environmental health hazard that claims 6.5 million lives per year globally. It is caused by a variety of pollutants, including particle pollution, ground-level ozone, carbon monoxide, lead, nitrogen oxides, sulfur oxides, and volatile organic compounds (VOCs). These pollutants can have detrimental effects on both human health and the environment, with particle pollution, or PM2.5, being of particular concern due to its ability to penetrate deep into the lungs and even the bloodstream. Outdoor air quality has improved in recent years, but significant challenges remain, and certain groups, such as those with asthma, are more vulnerable to the negative impacts of air pollution.

Ground-level ozone

The health effects of ground-level ozone include triggering a variety of health problems, especially for children, the elderly, and people with lung diseases such as asthma. Exposure to ground-level ozone has been linked to pre-mature mortality, hospital admissions, and an increase in asthma symptoms. In addition to its impact on human health, ground-level ozone can also damage vegetation, decrease crop productivity, and harm synthetic materials and textiles.

To address the issue of ground-level ozone, the EPA in the United States has implemented regulations to help states reduce ozone levels in outdoor air. These regulations include designating areas as attainment or nonattainment based on air quality standards and working with states and tribes to improve air quality in nonattainment areas. The EPA's rules to reduce emissions of pollutants that form ground-level ozone are designed to help state and local governments meet the Agency's national air quality standards.

Particle pollution (PM2.5)

Particle pollution, or particulate matter (PM), refers to a mixture of solid particles and liquid droplets found in the air. PM2.5, specifically, refers to fine inhalable particles with diameters generally 2.5 micrometers and smaller. To put this into perspective, the average human hair is about 70 micrometers in diameter, making it 30 times larger than the largest fine particle. These particles come in a variety of sizes and shapes and can be composed of hundreds of different chemicals. Some common sources of PM2.5 include emissions from the combustion of gasoline, oil, diesel fuel, or wood, as well as construction sites, unpaved roads, fields, smokestacks, and fires.

PM2.5 is particularly concerning because of its health risks. Due to their small size, these particles can be inhaled and penetrate deep into the lungs, and in some cases, even enter the bloodstream. Short-term exposure to PM2.5 (up to 24 hours) has been linked to premature mortality, increased hospital admissions for heart or lung issues, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days. The World Health Organization's Global Burden of Disease Project has identified PM2.5 as the air pollutant associated with the greatest proportion of adverse health effects, both in the United States and worldwide.

People with pre-existing health conditions, particularly related to the heart or lungs, are more susceptible to the negative impacts of PM2.5. For example, those with asthma may experience worsened symptoms on days with high pollution levels. Additionally, infants, children, and older adults are more vulnerable to the health risks associated with PM2.5 exposure.

To mitigate the risks of PM2.5, individuals can take precautions such as spending more time indoors, choosing less strenuous outdoor activities, and avoiding busy roads with high emission levels. Regulatory bodies, such as the EPA, also play a crucial role in implementing rules to reduce emissions of pollutants that contribute to PM2.5, ultimately improving air quality and protecting public health.

Carbon monoxide

CO pollution occurs primarily from emissions produced by fossil fuel-powered engines, including motor vehicles and non-road engines and vehicles such as construction equipment and boats. Higher levels of CO generally occur in areas with heavy traffic congestion. Other sources of CO emissions include industrial processes (such as metal processing and chemical manufacturing), residential wood burning, and natural sources like forest fires.

Indoor sources of CO include gas stoves, malfunctioning or improperly vented gas appliances (such as water heaters, furnaces, and clothes dryers), space heaters, fireplaces, tobacco smoke, and car emissions. The highest levels of CO typically occur during the colder months when inversion conditions (when air pollution becomes trapped near the ground beneath a layer of warm air) are more frequent.

CO can have harmful health effects by reducing oxygen delivery to the body's organs and tissues. Exposure to lower levels of CO is particularly serious for those with heart disease, and can cause chest pain, reduced exercise capacity, and other cardiovascular effects with repeated exposure. Even healthy individuals can be affected by high levels of CO, potentially developing vision problems, reduced ability to work or learn, reduced manual dexterity, and difficulty performing complex tasks. At very high levels, CO can cause dizziness, confusion, unconsciousness, and even death.

Nitrogen oxides

Nitrogen dioxide (NO2) is the most common nitrogen oxide and is considered the primary pollutant. It is rapidly formed when nitric oxide (NO) reacts with oxidants such as oxygen, ozone, and VOCs. High combustion temperatures increase the amount of nitric oxide generated. NO2 can irritate the airways of the human respiratory system, aggravate respiratory diseases like asthma, and potentially increase susceptibility to respiratory infections. Longer exposure to elevated NO2 concentrations may even contribute to the development of asthma.

To address NOx emissions, the EPA has implemented national and regional rules to reduce NO2 and NOx levels. These regulations help state and local governments meet the National Ambient Air Quality Standard (NAAQS). Similar strategies are being employed in the UK, but increasing road traffic remains a challenge.

Volatile organic compounds (VOCs)

Sources of VOCs

VOCs are emitted by a wide array of products, including:

• Paints, varnishes, waxes, and lacquers
• Paint strippers
• Cleaning supplies
• Pesticides
• Building materials and furnishings
• Office equipment, such as copiers and printers
• Correction fluids and carbonless copy paper
• Graphics and craft materials, including glues and adhesives
• Photographic solutions
• Personal care products
• Tobacco smoke
• Fuels

Health Effects of VOCs

Breathing in VOCs can cause a variety of adverse health effects, including:

• Eye, nose, and throat irritation
• Headaches
• Nausea
• Dizziness and loss of coordination
• Difficulty breathing
• Long-term damage to the liver, kidneys, and central nervous system
• Increased risk of cancer
• Worsening of symptoms for people with asthma and COPD

Reducing Exposure to VOCs

To reduce exposure to VOCs, it is recommended to:

• Read product labels and choose products that are low in VOCs
• Avoid or limit the use of items with harmful ingredients
• Safely dispose of unwanted products
• Increase ventilation, especially when using products containing VOCs
• Let new products air outside before bringing them indoors
• Ensure effective ventilation systems in offices and schools to reduce VOCs produced by equipment such as printers and copiers

Frequently asked questions