In Philadelphia, the order to work from home issued by Gov. Tom Wolf in mid-March forced all non-essential workers to remain home, disrupting businesses and people’s daily lives. However, an unexpected result is that this order is thought to have had a positive impact on the city’s air pollution. 

The 2018 American Community Survey estimated that 400,000 people drive to work every morning in Philadelphia. With non-essential businesses closed and people working from home, the number of commuters has dropped dramatically. Consequently, the city’s air quality has improved significantly. According to the Environmental Protection Agency’s Air Quality Index, Philadelphia is currently experiencing the longest streak of “good” air quality days in 40 years. This streak began on March 13, just before all non-essential businesses were ordered to close. 

The AQI is a measure of air quality that accounts for several different pollutants, weather conditions, and pollutant emissions sources, such as cars that run on fossil fuels. Philadelphia’s air quality in the spring tends to undulate between “good” and “moderate” conditions. 

Lockdowns Temporarily Clear the Air

Globally, the decrease in air pollution is detectable from space. NASA satellite images show that concentrations of nitrogen dioxide (NO2), an air pollutant caused by combustion, significantly dropped over China in January and February compared to the same time the year before.

Transportation restrictions and decreased demand for energy from combustion power plants resulted in cleaner air. According to the Centre for Research on Energy and Clean Air, these restrictions impacted two of the largest sources of nitrogen dioxide in China, causing a 36% decrease in coal consumption in February, and a 70% decline in domestic flights. In addition, there was a 21.5% increase in good air quality days in February in the region compared to the year before.

Italy, which has also implemented strict quarantine measures, has seen a similar improvement in nitrogen dioxide levels. After officials placed the country on lockdown, European Space Agency satellites detected a noticeable decrease in nitrogen dioxide.

However, Li Shuo, a climate policy advisor for Greenpeace East Asia, notes that air quality improvements from decreased economic activity may be short lived. Because the improvements in air quality have been linked to economic disruption, it is likely that once the threat of coronavirus passes, these areas will rapidly increase their economic activity, and with it their production of pollutants like nitrogen dioxide. 

Similarly in the United States, as states slowly begin to reopen we can expect to see our air pollution levels increase. Air pollution is also impacted by temperature, so as the weather warms, we may see an increase in pollutants such as the respiratory irritant ground level ozone, which occurs when nitrogen oxides like NO2 interact with volatile organic compounds in the presence of sunlight and heat. 

Another Public Health Hazard 

Air pollution poses a significant threat to public health. The World Health Organization estimates that 4.2 million people die prematurely each year as a result of exposure to air pollution. Marshall Burke, an assistant professor at Stanford University’s Department of Earth System Sciences, estimated that the recent improvement in air quality due to coronavirus containment measures in China may have saved between 1,400 and 4,000 children under five and 51,700 - 73,000 adults over 70. 

Air pollutants like nitrogen dioxide that are typically abundant in large economic hubs harm human health because they are respiratory irritants. Short-term inhalation of pollutants like nitrogen dioxide irritates the respiratory system and exacerbates respiratory diseases such as asthma. Studies have found that long-term inhalation of pollutants from emissions or smoking can cause individuals to develop asthma or become more susceptible to respiratory infections. 

In a recent study from the Harvard University T.H. Chan School of Public Health, researchers examined the relationship between coronavirus deaths and exposure to PM2.5, very fine particulate matter that can present lung and heart problems when inhaled. After accounting for factors in demographics, such as age, smoking, weather, and socioeconomic variables, the study found that just a slight increase in one’s exposure to PM2.5 was associated with an 8% increase in the COVID-19 death rate. Because the coronavirus pandemic is only a recent development, more research will be done on this topic as scientists learn more about the disease.

Looking to the Future of Air Pollution

While this period of working from home has done wonders for our air quality, humans are still social creatures, so a totally remote workforce is unlikely in the future. Collaborating with coworkers through video chat software will never be the same as meeting in person. 

People around the world are experiencing and appreciating cleaner air. Perhaps when our lives return to normal, we can work toward better air quality year-round, with less dependence on fossil fuels that contribute to air pollution and warm our planet.

There are a number of decisions we as individuals can make to help achieve this goal. We can decide to buy locally, which, like working from home, reduces spending fossil fuels to ship goods from around the world. Others may choose to use public transportation when they return to their offices or opt for renewable energy that produces fewer emissions. 

Even though we are in a dark time, we can learn from it.