New air-purifying technology being tested by the Long Island Rail Road could kill the coronavirus and virtually all other airborne viruses, but until it is installed, most trains will continue to rely on decades-old ventilation systems that LIRR officials say are effective.
Among several new strategies being considered to combat the spread of viruses on trains is one that would replace standard air filters on train heating, ventilation and air-conditioning systems (HVAC) with an electrical grid that LIRR officials said would kill 99.995% of any airborne viruses and bacteria. Before returning to the car, the air is also ionized, which helps knock down particles in the air.
The technology, developed by Madrid, Spain-based firm Merak — which also designed and manufactured the LIRR's current HVAC system — would be the first of its kind in the United States and is used in transit systems in other countries, including China, according to the LIRR.
The LIRR is installing the technology on a single train car. After a testing phase, officials said they are optimistic the technology could be rolled out across the railroad's fleet of 1,100 cars widely within months, equipping trains with an air treatment system that would outperform even the highest-rated air filters.
"This is just one part of the overall effort. We want the riders to know that they can ride the trains safely," LIRR president Phillip Eng said in an interview. "This is all about everyone doing their part. We’re doing what we can here at the railroad, including looking at new technology."
According to the Centers for Disease Control and Prevention, COVID-19 is primarily transmitted through droplets expelled by infected people. Because of that, medical and transportation experts have said that adequate ventilation is key to preventing the spread of the virus in public, indoor settings, including trains.
With nearly three-quarters of regular commuters yet to return to the LIRR, railroad officials are offering assurances that the air flow inside the average 85-by-10½-foot train car is better than in most indoor settings.
HVAC systems as old as trains
The LIRR's HVAC systems are typically as old as the trains — the majority of which came into use about 18 years ago. Those on the LIRR’s newest trains — M9s — have improved controls and diagnostic capabilities, but function similarly to those on older models.
HVAC systems on LIRR trains are roof-mounted. There are two units on each car, allowing for redundancy, efficiency and expanded cooling and heating capacity, said Craig Daly, the railroad’s chief mechanical officer.
The units work similarly to those found in other places, with an evaporator, condenser and compressor. The units draw in air from the car through grilles on the ceilings of both ends of a train, process that air through a filter, then return it to the car through vents running along the entire length of a train car’s ceiling.
The downward trajectory of the airflow also has proved helpful at knocking airborne particles to the ground, Eng said. "It’s driving the air down, rather than pulling the air up, which, in this type of situation, is what you want," he said.
Every 92 days, workers replace the air filters, which have a minimum efficiency reporting value, or MERV rating, of around 7. That's just half of the MERV 14 rating recommended by experts to capture airborne virus, but Daly said there are other important factors when considering ventilation in a train, as opposed to a stationary building.
The LIRR is looking at using filters with a MERV 15 rating, but Daly cautions they could result in reduced airflow inside trains, as they would clog more easily.
Currently, all the air in a train car is filtered about 44 times an hour, according to the LIRR. And about one-third of the air that’s pumped in is fresh air pulled from above the roof of the cars. This is one major way these systems differ from those in buildings, said Daly, who noted that the air inside a car is replaced by outdoor air 12 times an hour, or about every five minutes.
According to a report prepared by transportation firm Sam Schwartz and the American Public Transportation Association, the air replacement cycles on LIRR trains meet the standards set by the CDC and the American Society of Heating, Refrigerating and Air-Conditioning Engineers for isolation rooms in medical facilities. They well exceed the standards for classrooms (5-6 times an hour) and for restaurants (6-8 times an hour).
Although the HVAC systems are standard for a railroad, Daly said one advantage the LIRR has over its commuter system counterparts is the number of stations — 124 — and high frequency of stops. At each stop, trains cars open, letting even more fresh air in.
Customers don't give it much thought?
Construction worker David McSkane, who has commuted on the LIRR throughout the pandemic, said he has "never really given much thought" to the ventilation systems on LIRR trains, and believes most riders haven’t either.
"I just figure as long as I’m wearing the mask, I feel relatively safe," said McSkane, 47, of Oyster Bay. "I’d say most people don’t realize how good the filters are, or how good they could be. That makes me more comfortable. Maybe they should be promoting that more."
Hofstra University associate professor Anthony Santella, who specializes in public health and infectious diseases, agreed that the railroad needs to do a better job of promoting its efforts to the public, in part because there's little widely known about the potential transmission of COVID-19 on its trains.
"It’s a unique environment. All the evolving science that’s coming out about COVID really focuses on the kind of stationary indoor environment, like the workplace, the school, the household, etc. We’re largely not seeing a lot of talk about public transportation," said Santella, who believes the "very technical" specifics of the LIRR’s HVAC systems matter little to its customers.
"The average person who rides the Long Island Rail Road … is not going to care anything about any of those details," Santella said. "They want to know, ‘Is my risk elevated by riding the train? Yes or no?’ "
Eng said the railroad has seen "virtually zero cases" of coronavirus among its train crew members in recent months. Helping prevent the spread on trains, Eng said, is a 98% mask compliance rate among riders, daily disinfecting of trains and stations, and new features on the LIRR’s mobile app that allow customers to see, in real time, how crowded a train is before boarding it.
In addition to the air purifying systems, and the higher-rated air filters, the LIRR has been testing other technology to combat the spread of COVID-19 on trains, including ultraviolet light, and antimicrobial disinfectant solution that could kill viruses for weeks with a single application.