Air pollution within the Philly metro is far worse than on the streets

The air quality within the City Hall subway station in downtown Philadelphia is far worse than on the sidewalks directly above the station. This is certainly one of our key findings latest study published within the Journal of Exposure Science & Environmental Epidemiology.

We are one environmental scientist and a biochemist who assessed the air quality on the fifteenth Street-City Hall station in Philadelphia. We focused on this station because our previous study found that it has highest particulate matter pollution Among Philly's 12 subway stations, we measured the busy Market-Frankford or Broad Street lines.

Most worryingly, there was about ten times more soot contained in the station than at street level. A serious component of that is black carbon, commonly known as soot Fine dust pollution within the air. It is released in the course of the incomplete combustion of fossil fuels and the burning of biomass, and inhalation is linked to adversarial health effects reminiscent of asthma, heart attack and lung cancer.

Our results suggest that the soot is generated by the subway system itself. Graphite is used on brake pads a possible source.

We also found that the concentration of ultrafine particles (UFP) was about 1.7 times higher underground than above ground. While wonderful particles have a diameter of as much as 2.5 micrometers – approx 35 times smaller as a wonderful grain of beach sand – ultrafine particles are 0.1 microns or smaller. These particles are worrisome because they penetrate deep into people's lungs.

Limited access to outside air, frequency of trains, large variety of passengers, and site in the center of downtown could also be among the reasons for the high levels of particulate matter at fifteenth Street Station.

Subway air quality has already been studied in Philadelphia and several other other US cities, including Boston, New York City and Washington, D.C. A study by 71 subway stations in these metropolitan areas found PATH stations New York and New Jersey have the very best concentrations of particulate matter. This study also found the same concentration of wonderful particles, primarily iron and carbon, in Philadelphia, as we found.

However, more types and sizes of particles were measured in our study.

Why it matters

Our study highlights the necessity for Philadelphia to watch air quality in its subways and reduce air pollution exposure for commuters and subway employees.

Several major aspects contribute to air pollution in subways. These include the age of the subway system, wear on the wheels and rails, the frequency of trains, the usage of a graphite lubricant on the brake pads, poor ventilation, the depth of the station, and restrictions on access to outside air and traffic.

Better ventilation, the usage of platform screen doors, and more frequent cleansing to reduce dust are some ways to enhance air quality.

Although we consider that subway air quality must be improved, our results don’t suggest that commuters should avoid the subway. Air pollution levels vary widely between stations and over time, and commuters spend relatively short periods of time in subway stations.

People with health problems, especially lung disease, can provide excellent protection by wearing an N95 mask or N95 mask even a surgical mask. Subway employees can use air purifiers to cut back their exposure to particulate pollution.

How we do our work

Using three forms of monitors, we concurrently measured particle pollution within the underground subway platform and the above-ground pedestrian walkway. In the summer of 2022, we carried out measurements for six hours a day, roughly from 9 a.m. to three p.m., on five weekdays.

What's next?

The next step on this project is to show lung cells within the laboratory to air pollution particles from fifteenth Street Station and measure the oxidative stress attributable to the particles. This stress contributes to chronic diseasesincluding asthma, chronic obstructive pulmonary disease and lung cancer.

We will even study the forms of air particles and the degrees of various metals in them to find out what effects these subway particles have on lung cells.