Airborne Pollutants: Reducing Harmful Airborne Contaminants

Hazardous air pollutants, also known as toxic air pollutants or air toxics, are known or suspected to cause cancer or other serious health issues such as harm to the nervous system and brain, irritation to the eyes, nose and throat, coughing and wheezing, impaired lung function, and harm to the cardiovascular system. They can be released into the environment from natural sources, such as volcanic eruptions and forest fires, but most stem from human-made sources. Hazardous air pollutants can be gases, such as hydrogen chloride, or compounds and metals such as asbestos, cadmium, mercury and chromium. The Clean Air Act requires the EPA to regulate hazardous air pollutants from categories of industrial facilities in two phases. The EPA has implemented various programs to reduce hazardous air pollutants, including the National Clean Diesel Campaign, Clean School Bus USA, and SmartWay.

Reducing emissions from vehicles and engines

Motor vehicles are a significant source of air pollution, and there are several ways to reduce emissions from them. Firstly, choosing a less-polluting vehicle is essential. Opting for fuel-efficient vehicles with low greenhouse gas emissions, such as plug-in hybrid electric, hydrogen fuel cell, or cleaner-burning gasoline cars, can significantly reduce environmental impact. Electric, hybrid, and even compact fuel-efficient gas vehicles are becoming more affordable and accessible, offering a cleaner alternative to traditional cars.

Secondly, maintaining your vehicle is crucial. Regular servicing, tune-ups, and adhering to the manufacturer's maintenance schedule can ensure your car runs efficiently and minimises emissions. This includes using the recommended motor oil and keeping tyres properly inflated, as underinflated tyres increase fuel consumption and emissions. Additionally, older vehicles with malfunctioning emission controls may pollute more, so it's important to address any check engine light issues promptly.

Thirdly, driving habits play a significant role in reducing emissions. Minimising vehicle use by opting for alternative transportation methods such as walking, biking, carpooling, or using public transit can substantially decrease emissions. Planning trips efficiently by combining errands and avoiding peak-hour traffic can also reduce the number of miles driven and lower emissions. Driving efficiently by avoiding unnecessary acceleration and high speeds further reduces fuel consumption and emissions.

Furthermore, reducing idling time is essential. Turning off the engine when the car is idle saves more fuel than restarting the engine, and modern vehicles do not require prolonged warming up in cold weather. This simple action not only reduces air pollution but also saves fuel and engine wear. Additionally, optimising home deliveries by consolidating packages and choosing flexible delivery time windows can help reduce unnecessary vehicle trips and associated emissions.

Lastly, when using lawn and gardening equipment, opting for manual or electric and battery-powered tools can significantly reduce emissions compared to gas-powered engines. Commercial-grade landscaping machinery with advanced emissions reduction technologies is also available for those needing more heavy-duty equipment. By implementing these measures, individuals can play a crucial role in reducing emissions from vehicles and engines, contributing to improved air quality and public health.

Reducing indoor air pollution

Ventilation

One of the most important ways to improve indoor air quality is to ensure good ventilation. Opening windows and doors can help to increase the ventilation rate and encourage a good exchange of indoor and outdoor air, but this may not always be possible due to allergies or extreme temperatures. In these cases, it is beneficial to use fans, such as window, attic, or exhaust fans, to increase the ventilation rate. Local exhaust fans in bathrooms and kitchens can help to remove contaminants directly from these rooms. Advanced designs of new homes are starting to feature mechanical systems, such as energy-efficient heat recovery ventilators, that bring outdoor air into the home.

Air cleaners and filtration

Air cleaners and filtration systems can also help to improve indoor air quality. However, it is important to note that air cleaners are generally not designed to remove gaseous pollutants, and their effectiveness depends on factors such as the efficiency of pollutant collection and the air circulation rate. Table-top air cleaners, for example, may not be sufficient for removing pollutants from strong nearby sources.

Source control

Another strategy for improving indoor air quality is to eliminate individual sources of pollution or reduce their emissions. Some sources, like those containing asbestos, can be sealed or enclosed, while others, like gas stoves, can be adjusted to decrease emissions. Source control is often a more cost-efficient approach than increasing ventilation, as increasing ventilation can lead to higher energy costs.

Other strategies

In addition to the three basic strategies outlined above, there are several other simple steps that can be taken to reduce indoor air pollution:

• Avoid smoking indoors
• Use natural cleaning supplies to minimise the use of harsh chemicals that can irritate the nose, mouth, lungs, and skin
• Keep pets out of bedrooms and bathe them regularly to reduce allergy-causing dander
• Use a dehumidifier and/or air conditioner to reduce moisture and mould
• Put down a doormat and establish a shoes-off policy to reduce pollutants carried into the house
• Vacuum often, especially if you have pets, and use a microfiber dusting cloth to capture more dust
• Minimise carpeting, as it can trap pollutants such as dust mites, pet dander, and mould spores
• Keep trash covered to avoid attracting pests
• Avoid air fresheners, scented candles, and incense, as these can trigger asthma
• Test your home for radon and use carbon monoxide detectors

Regulating industrial facilities

The first phase is "technology-based," where the EPA develops standards for controlling air toxic emissions from specific industry groups or "source categories." These standards, known as Maximum Achievable Control Technology (MACT), are based on emission levels already achieved by controlled and low-emitting sources within the same industry. The EPA sets limits on how much of these pollutants can be present in the air and has the authority to regulate emissions from sources like chemical plants, utilities, and steel mills.

Within eight years of establishing the MACT standards, the Clean Air Act directs the EPA to transition to the second phase, a "risk-based" approach called residual risk. During this phase, the EPA assesses the remaining health risks from each source category to determine whether the MACT standards adequately protect public health and the environment. If the MACT standards are found to be insufficient, the EPA is required to implement more health-protective standards.

Furthermore, the Clean Air Act mandates that every eight years after setting the MACT standards, the EPA must review and revise them to incorporate advancements in air pollution controls and prevention methods. Since 1990, the EPA has issued regulations limiting emissions of air toxics from over 174 categories of major industrial sources, including chemical plants, oil refineries, aerospace manufacturers, and steel mills. These regulations are projected to significantly reduce annual air toxic emissions when fully implemented.

In addition to regulating major sources, the EPA also addresses smaller sources, known as area sources. These facilities typically have lower emissions but can be numerous and located in heavily populated areas. Examples include gas stations and dry cleaners. The EPA has completed emissions standards for these area sources and projects that all regulated area sources will be in compliance by the specified deadlines.

Controlling mobile sources

Mobile sources of air pollution include motor vehicles, airplanes, locomotives, and other engines and equipment that can be moved from one location to another. These sources are responsible for over one-third of air toxic emissions from human activity in states like Colorado. To reduce hazardous airborne pollutants from mobile sources, several strategies and regulatory standards have been implemented.

One approach is to establish design and fuel standards for mobile sources. For example, the Corporate Average Fuel Economy (CAFE) standards set minimum fuel economy levels that vehicle manufacturers must meet. These standards aim to reduce emissions by encouraging the production of more fuel-efficient vehicles. Additionally, policies such as the ban on leaded gasoline in the United States help reduce toxic emissions.

Another strategy is to implement vehicle inspection and maintenance programs. In Colorado, for instance, vehicles in ozone nonattainment areas undergo periodic inspections to ensure proper functioning of emission controls and engines. Vehicle owners are responsible for making any necessary repairs to address emission deficiencies identified during these inspections.

Regulatory programs have also been established to specifically target mobile source air toxics. The Tier 3 vehicle and fuel standards issued in 2014 by the US Environmental Protection Agency (EPA) are expected to reduce emissions of air toxics from motor vehicles by 10 to 30 percent by 2030. Similarly, the 2007 Mobile Source Air Toxics Rule controlled the benzene content of gasoline and vehicle emissions at cold temperatures, resulting in significant reductions in ambient benzene concentrations.

Non-regulatory initiatives also play a role in reducing mobile source air toxics. Examples include the National Clean Diesel Campaign, Clean School Bus USA, and EPA's Ports Initiative. Furthermore, the Diesel Emissions Reduction Program (DERA) promotes the deployment of pollution-controlling technologies in diesel fleets, offering significant public health and air quality benefits.

In addition to these measures, transitioning to lower greenhouse gas-intensive fuels, such as natural gas, and renewable energy sources like wind and solar power can also help reduce air toxics from mobile sources.

Identifying hazardous pollutants

Hazardous air pollutants, also known as toxic air pollutants or air toxics, are those that are known or suspected to cause cancer or have other serious health effects. They can also adversely affect the environment. These pollutants come from a variety of sources, including human-made sources such as vehicles and industrial facilities, as well as natural sources like volcanic eruptions and forest fires.

Sources and Emissions: Hazardous air pollutants can originate from various sources, and identifying these sources is the first step towards recognizing the pollutants themselves. As mentioned, they can come from human-made sources like mobile vehicles (cars, trucks, buses) and stationary sources (factories, refineries, power plants). Additionally, indoor sources, such as certain building materials and cleaning solvents, can also release toxic pollutants. By understanding the sources, we can narrow down the types of pollutants likely to be present.

Monitoring and Measurement:

• Ambient Air Quality Monitoring: Government agencies, such as the Environmental Protection Agency (EPA) in the United States, often employ air quality monitoring networks. These networks utilize specialized equipment to measure the concentrations of various pollutants in the air. By collecting and analyzing data on pollutant levels, it becomes possible to identify hazardous substances and their sources.
• Emissions Data: Industrial facilities and other sources of pollution are often required to report their emissions data. This data includes information on the types and quantities of pollutants released into the environment. By analyzing these emissions inventories, hazardous pollutants can be identified, and their sources can be held accountable.
• Air Toxics Screening Tools: The EPA, for instance, has developed tools like Air Toxics Screening Assessment (AirToxScreen) to provide communities with information about health risks from air toxics. These tools use updated data and risk analyses to help identify existing and emerging air toxics issues.

Health Impact Studies: Conducting studies and analyzing health data can help identify hazardous pollutants retrospectively. By studying the health outcomes of populations exposed to certain pollutants, researchers can determine the harmful effects of specific substances. This information is crucial for regulatory and preventative measures.

Environmental Sampling and Analysis: Collecting and analyzing environmental samples, such as soil, water, and plant matter, can help identify the presence of hazardous pollutants. This is especially important for understanding the impact of pollutants on ecosystems and the food chain. For example, testing fish in lakes for mercury levels helps identify the accumulation of hazardous substances in the environment.

National and International Lists: Many governments and organizations maintain lists of known hazardous air pollutants. These lists are regularly updated and serve as a reference for regulatory bodies and researchers. An example is the original list of hazardous air pollutants by the US EPA, which includes specific chemicals and compounds known to have toxic effects.

By employing these identification methods and considering the sources and impacts of pollutants, we can better understand the nature and extent of hazardous airborne pollutants. This knowledge is essential for developing effective strategies to reduce their release into the atmosphere and protect human health and the environment.

Frequently asked questions