Lelia N. Hawkins Air Pollution FAQ

Questions about the composition of air

What kinds of chemicals are in the air we breathe?

Our air is mostly dinitrogen (N2) and dioxygen (O2). Some examples of harmful chemicals in the air of cities include ozone (O3) and aromatics like benzene (C6H6). In addition to these gas-phase chemicals, there are tiny particles (aerosol) made up of compounds like nitrate, sulfate, ammonium, and many organic compounds such as carboxylic acids, aldehydes, and hydrocarbons (CxHy molecules).

How do specific air pollutants like hydrocarbons, nitrogen dioxide, and sulfur dioxide, chemically form and affect humans?

The short, simplified answer is that hydrocarbons are typically emitted as unburnt fuel from cars and trucks, as well as from industrial processes. Nitrogen oxides are generated when combustion occurs in the air (because air is 78 percent dinitrogen) and sulfur dioxide is emitted when fuels containing sulfur are combusted in air. Coal is an example of a fuel with a high sulfur content. When coal is not treated for sulfur and is burnt, SO2 is emitted. Nitrogen and sulfur oxides contribute to acid rain while hydrocarbons and nitrogen oxides are key precursors to photochemical smog (ozone and particulate matter). Both are hazardous to our health because they contribute to asthma, cardiovascular disease, and brain damage.

What is the most harmful form of air pollution? Why?

The harm in air pollution comes in many forms, so it is impossible to claim one form is the “worst.” However, for respiratory issues, the most harmful type of pollution would be the very smallest (below 100 nm in diameter) particles, containing strong acids like sulfuric acid or carcinogens like polycyclic aromatic hydrocarbons. However, one might argue that the most harmful type of pollution is carbon dioxide because it contributes to global climate change which has worldwide consequences and has a long atmospheric lifetime.

What is the most interesting project that you have been a part of to help this issue?

The most interesting research I have done was on a ship off the coast of Chile, looking at the effect of air pollution on clouds and the global climate. We even sailed through the Panama Canal!

How does methane contribute to air pollution?

Methane is a powerful greenhouse gas and it absorbs infrared radiation more efficiently than carbon dioxide. It also can participate in smog formation, because it can react with oxidants like ozone and nitrogen dioxide.

Questions about the effects of air pollution

How does air pollution affect the world?

Depending on the KIND of air pollution, the effect changes. In some cases, very acidic pollution can deteriorate statues and buildings. Trees and plants are harmed by strong oxidants and acids. Freshwater can be contaminated as well. Breathing low levels of air pollutants cause irritation of lung tissues but high levels can cause asthma attacks and even strokes. Greenhouse gas pollution leads to climate change. However, hazy smog also keeps the planet a little cooler than it would otherwise be, so in that sense, it’s good because it offsets some of the warming we experience from carbon dioxide.

Does air pollution cause diseases?

What kind of diseases does it cause?

Yes, particulate air pollution (like smog) can cause asthma, cardiovascular disease, and strokes. If the level of carcinogens is high, then people can develop cancer (this is like smoking).

Is air pollution affecting the atmosphere?

Yes, air pollution can affect the atmosphere because the mixed part of the atmosphere (the troposphere) is actually very small in volume. That means adding even small amounts of pollutants impacts the air quality we experience.

Other than health, how does pollution affect people daily?

Air pollution reduces the visibility in cities so that it becomes hard to see (like in foggy conditions). It can also erode statues and buildings if they are made of carbonate and the pollution is acidic.

For how long do you think pollution will continue to be a problem?

This depends on the kind of pollution you are interested in. We are constantly finding new ways to clean up pollution but also continuously adding new kinds of pollution to the environment, as technology advances. So while lead (from leaded paint and gasoline) is no longer being added to the environment, plastics are increasing in our oceans. There will always be pollution.

Is outdoor pollution more of a concern than indoor pollution? Why?

This depends on your location. In many developing nations, indoor air pollution is as bad or many times worse than outdoor air pollution because indoor cookstoves burning biofuel are unfiltered and produce large amounts of smoke (tiny particles). The use of highly scented cleaning products can lead to high indoor pollution levels. Using an air purifier with ozone, in addition to scented cleaning products, can be very bad. Burning incense is another major source of particles indoors.

Questions about the causes of air pollution

What are the major sources of air pollution?

The major sources of air pollution are the combustion of fossil fuels (coal, gas, oil) and biomass (trees, dung). In photochemical smog (like in Los Angeles), you also need sunlight.

What do you think is the worst source of air pollution and why?

Fossil fuel combustion is the primary cause of air pollution in most places. This includes burning coal, oil, and gasoline for energy. This is because they have other elements that do not burn cleanly, leaving behind material that forms air pollution. In developing nations, burning wood and dung cause the most air pollution.

Why is air pollution so bad in Asia?

Air pollution is bad in cities like Beijing due to two factors: (1) high emissions of gases and particles and (2) stagnation events, where the air is not mixed with clean air but remains stagnant (stable) and the pollutants build up instead of being blown away. The emissions result from driving older cars with poorly designed engines and burning lots of coal for energy that has sulfur in it. That sulfur turns to sulfate and creates many particles resulting in the haze you see. The levels of pollution necessary for smog to look like fog are very dangerous for us to breathe.

Is air pollution the only cause of global warming?

No, air pollution is not the only cause of global warming. Deforestation is a big one. So is the agricultural beef industry (methane is emitted by cows).

Questions about the solutions of air pollution

What other forms of energy would you suggest our generation use in order to stop the burning of coal and minimize the need for fossil fuels? And why?

Any energy that produces less waste and fewer pollutants is a good choice. Common examples include solar energy, wind energy, and geothermal energy. Hydroelectric power can be clean, but sometimes the placement of dams impacts the natural habitat in a detrimental way.

I’m worried about the future of air quality in the United States. What can you tell me about that?

Actually, in the US we have fairly strict air quality regulations for pollutants like NO2 and hydrocarbons as well as strict standards for ozone and particle counts. Most places in the US, on most days, meet those standards. Air quality in the US has dramatically improved since the 1970s when wearing a mask would have been advisable though it was not common practice. At my house, we can see our local mountains every day (which wasn’t true in the 1970s). Cars, though increasing in number, are becoming extremely clean and the use of electric cars has further improved the smog situation. The real concern in the US is greenhouse gas emissions, like carbon dioxide and methane, which are increasing and require stricter standards to avoid catastrophic global climate change. These pollutants are not harmful to breathe at current levels, but they absorb infrared radiation and heat the planet.

Why is it so hard to lower the amounts of air pollution we emit into the air?

It is very hard to lower the amounts of pollution because our population is growing rapidly and our lives are becoming more energy intensive. Therefore, innovations in technology must outpace population growth.

What do you think about the approach our President and Congress are taking on the topic of air pollution and fossil fuels being used?

The current administration seems to be operating on the premise that our environment is infinitely capable of absorbing our pollutants without any detrimental effects. This reasoning runs counter to all credible scientific work in the field, and I believe this practice is extremely short-sighted and irresponsible. I’m hopeful that future administrations will work toward solutions for air quality that are based on science.

In your opinion, what do you think is the best way that students like us could lend a hand in preventing further air pollution?

Raise awareness about the issue, study science and technology to help create clean technologies, and advocate for better practices in energy use.

Questions about international, historical, and future issues regarding air pollution

What countries pollute the planet the most?

This depends on the kind of pollution. Developing nations like China and India are known to have very high levels of smog type pollution. The US has much lower levels. With respect to greenhouse gases like carbon dioxide, China emits the most but the per capita (per person) emissions are only half that of the United States. According to the 2015 EDGAR database, Qatar has the highest per capita emissions. As the developing nations create an increased quality of living for their citizens, their per capita pollution will increase as well. This is a major concern for climate change as well as air quality.

Do proposed solutions to climate change affect other countries and their economic development?

Yes, restrictions on pollution of greenhouse gases necessarily impact economic development in the absence of new technologies. Some people support the idea of sharing technology with developing nations so that they may improve the standard of living for their citizens with green technologies rather than fossil fuel burning.

What are the leading countries in the prevention of air pollution?

European countries tend to be ahead of the curve with respect to climate change and reducing emissions.

What is the estimated time of the damage to be reverted?

Reducing emissions of smog-type pollutants results in immediate effects. However, greenhouse gases have long lifetimes, so we need to wait over 20 years, possibly up to 100 years, for the system to return to pre-pollution conditions if we stop emitting the gases today. This is a long time.

Has this been a problem before the 2000s?

Yes, since the industrial revolution (1850) we have been burning fossil fuels for energy and emitting carbon dioxide and other pollutants.

Will this affect future generations?

Yes, very likely there will be significant impacts to global climate in the next 20-50 years.