View of downtown Portland with orange skies
Toggle caption Photo by Ted Timmons - Wikimedia Commons

SASN Scientist Explains the Effects of Wildfires on Local and Global Air Quality

As a record-breaking wildfire season is still underway, fires are burning through much of the West Coast, bringing with it pollutants that make the air dangerously unsafe in areas, and affecting air quality thousands of miles east in New York and New Jersey, with smoke being carried far as parts of Europe. 

We asked Yuan Gao, Professor in the Department of Earth and Environmental Sciences at Rutgers University-Newark, about the current and long-term effects of the fires on air quality locally and afar.   

Dr. Gao shows undergraduate students procedures in the Gao Lab cleanroom
Dr. Gao (right) with undergraduate students working in her lab's cleanroom.

Dr. Gao’s research is in the fields of atmospheric chemistry, focusing on air quality and pollution and atmospheric deposition to aquatic systems. She and her team seek to understand the processes affecting the atmospheric composition and its impact on the human environment and global biogeochemical cycles. Her research has spanned many regions, from mineral dust over the Asian coast to air pollution over the US East Coast, and from the Arctic Ocean to the Southern Ocean and Antarctica.

In her research, Gao combines field measurements, laboratory experiments and numerical modeling to characterize the properties of atmospheric substances and to better understand land-atmosphere-ocean interactions. Her current research spans the globe, from air quality and urban air pollution around the metropolitan areas of New Jersey to studying atmospheric particles and nutrient iron deposition to the Arctic Ocean, Southern Ocean and Antarctica. During the COVID-19 period, the Gao group collected and are now analyzing observational data to address the COVID-19 impact on air quality in NJ. 


Why are there so many more fires this season than usual? 

More forest fires this season are primarily due to dry air (that is, little rainfall which results in much lower moisture level in the air), high air temperature and high winds. The triggers of such fires can be either natural processes such as lighting or human activities such as campfires left unattended. Fires could also be partly due to climate warming - air temperature increase by greenhouse gases emitted from anthropogenic [human-made] sources. 


Can you explain the science behind how fires affect the air quality of surrounding areas? 

Fires can affect air quality of not only surrounding areas but also far away regions. This is because fires generate and release large amount of substances into the air that are pollutants and that reduce air quality.  For example, volatile organic compounds and nitrogen oxides emitted from fires can form ozone in the air, which is an air pollutant that has negative impact on air quality. In addition, fires also release lots of tiny particles or debris into the air, and such small particles reflect and scatter sunlight, reducing visibility. These small particles could be enriched with toxic metals such as mercury, causing health effects when they are inhaled. The fire-generated pollutants can be transported by winds to regions far away from the fire sources, and therefore local fires can have profound negative impact on regional and even global scales. 


How long will these effects last? Is this a temporary problem or are there long-term ramifications for what's happening right now? 

The effects of fires on air quality can be reduced and disappear with time after the fires stop in the fire-impacted areas, as winds can disperse those substances derived from fires and particles from fires may also settle down through the air. However, health effects from fires may stay for quite a long time.  

Forest fires generate smoke that irritates our eyes, nose, throat, and lungs, and thus exposure to fires can surely affect our health. One way is by inhaling toxic substances emitted from fires, and health effects from this may stay for quite long time. Some people may have an asthma attack from the inhalation of high levels of smoke or particles in the fire-impacted areas. Hospital admissions may increase due to lung complaints during and after fire seasons. All of these could be long-term health effects, lasting over months and even a year or longer. 


What are some things people should do in affected areas to protect themselves? And what should they avoid? 

People in the fire affected areas should try their best to reduce and avoid their exposure to smoke. Things people could do include:  

  1. Stay indoors; keep a respirator handy or tightly snug to your face to filter out smoke if needed,

  2. try to stay in an isolated space away from outside impacted air, such as a room with windows closed,

  3. put up a filter or a portable air cleaner in the room where you stay to keep air clean.

  4. Pay close attention to local weather warnings and local air quality index readings, and follow safety and emergency instructions.

Are there certain types of filters or air cleaners that are better than others? What should someone look for when purchasing a filter?

With respect to maintaining clean air indoors, there are different kinds of air filters that can be used indoors. People should be encouraged to install high efficiency particulate air (HEPA) filters, based on rating such as by MERVs. MERVs stand for Minimum Efficiency Reporting Values that report the efficiency of a filter in capture of air particles between 0.3 and 10 micrometers in diameter. The higher the MERV rating, the more efficient the filter. For homes with individuals in at-risk groups including older adults and young children, people with heart and lung disease, and pregnant women, installing the filters with MERV 13 or higher is encouraged if all possible. People should closely follow the advice and instructions from their local public health agencies in selecting air filters appropriate for different situations.   


There have been reports that the fires have reduced air quality even on the east coast. How does that happen?  

One way for this to happen is that smoke plumes from fires in the West Coast could be picked up by atmospheric jet streams, which are swiftly flowing air currents with extremely high wind velocities traveling in the atmosphere from the western to the eastern U.S. And in such ways, pollutants emitted from fires on the West Coast can be carried to the East Coast, reducing air quality there.


Has your team been studying recent changes in air quality here in New Jersey? Can you tell us a little bit about your findings?  

My group has been studying Newark’s air quality with research taking place at Rutgers-Newark under the School of Arts and Sciences - Newark (SASN) and nearby suburban sites around Lyndhurst. We have studied air particles, gaseous air pollutants and precipitation, and the impact of air quality on human health. We also studied the connection between air quality and water quality. We have generated quite a few new datasets in this area. Below are some examples of our findings:

For air particles, we found that air quality varies on a seasonal basis. During the hot summer, particulate matter in Newark’s air was dominated by extremely small size particles of less than 1 micrometer in diameter, and such small particles could be easily inhaled into human lungs, causing health effects. We found that the extent of urban air pollution at Newark evaluated by the concentrations of particles of less than 2.5 micrometer in diameter (PM2.5) in the air was affected by winds, which in turn can affect respiratory health problems in this urban area. We also found that these small particles could absorb heat and contributed to higher air temperature in downtown Newark, a phenomenon known as “urban heat Island” that has occurred in this area is now better understood.

For gaseous air pollutants, we found that nitrogen oxides (NOx), highly reactive gases in the air, peak during morning rush hours in this area, indicating that the vehicle emissions is their main source. As pre-cursors of ozone, NOx contributed to the formation of ground-level ozone that often peaks in the early afternoon hours on hot summer days when people are advised to stay indoors. Ozone is a harmful air pollutant and it is a major ingredient of “smog” (meaning smoke and fog), affecting both people and the environment.

For precipitation, we found that at Newark, we often experienced acid rain, and the average rain pH was around 4.6, and the pH levels in some rain samples even fell below pH 4. (Note: normal rain has a pH of about 5.6, according to the EPA) The acidity in precipitation was caused by acidic air pollutants that dissolved in rain waters.

For the connection between air quality and water quality, we found that certain pollutants in the atmosphere can get into surface water through atmospheric deposition, affecting aquatic ecosystems in NJ. For example, we found that atmospheric deposition of nitrogen from air pollution emissions is one of the major contributors to the brown tides (or eutrophication, which are harmful algal blooms in waters) in Barnegat Bay that reoccurred over time.  


Should we be concerned about our own air quality in NJ? Is there anything we should be doing here on particularly bad days? 

I think we should be concerned about our own air quality in NJ, as it affects our health and our living environment. Air quality in the long term also affects regional climate change. On particularly bad air quality days, we should be informed well in advance in order to reduce exposure to air pollution outside. We should spend less time outdoors, especially children, the elderly and those with heart disease and with respiratory conditions. We should limit the time or intensity of outdoor exercises and avoid doing physical activities near the areas with high pollution, such as high traffic areas. 


Will this cause any long-term or permanent changes in air quality? Will it have other long-term effects?

Yes. This is because fires release large amounts of carbon dioxide, black carbon, brown carbon, small particles and ozone precursors into the atmosphere. These greenhouse gases and particles affect the atmosphere, radiation levels, cloud formation, and climate on regional and even global scales. Such changes in the atmospheric composition could be long lasting.

Greenhouse gases and particles emitted by fires affect the atmosphere, radiation levels, cloud formation, and climate on regional and even global scales.

The carbon dioxide and other greenhouse gases released from the fires will stay in the atmosphere for a long time and that will continue to warm the planet for many years to come. As consequences, such warming could fuel more dangerous wildfires. The fires can damage forests, reducing their ability to remove carbon dioxide from the air. Fires also contribute to the formation of ozone in the air, and ozone is an air pollutant and has degenerative impact on the growth of plants.

I think that some fires are preventable, as such fires often started by human error. We should equip ourselves with sufficient knowledge about wildfire prevention. We should also plan ahead of time in fire-prone regions and strictly follow safety and evacuation instructions issued by local and regional public health agencies.


Is there anything we as individuals or as a society can or should be doing to help prevent this from happening in the first place?

As fires emissions reduce air quality, we should be cautious with all activities in a wildfire-prone area and try to stop fires from starting. We should never leave a fire unattended, not start a fire on a high-wind day, dispose used matches in a cup of water, etc. 


Is this damage something that can be reversed? How?  

I think that the damage would be hard to reverse. 


Banner Photo above: View of Downtown Portland as seen from SE Portland during 2020 wildfires. The orange sky in places where the air quality is bad is caused by tiny particles in the air from pollutants such as vehicles running on the roads and power plant operations.  The orange, brownish, and even hazy colors are an optical phenomenon due to the interaction of sunlight with those particles. Photo by Ted Timmons - Wikimedia Commons.