Clean-air vigilantes are making $87.50 in 3 minutes by reporting idling trucks in NYC.

New York City law prohibits trucks from leaving their engines running for more than three minutes while parked, and Welde has been recording such violations using his phone. However, he claims that he has been physically harassed by truck drivers who disapprove of his side hustle.

I always anticipate an attack when I leave my home," said Welde, an environmental lawyer, to CNBC. "It's essential to be ready for a confrontation.

The Citizens Air Complaint Program, launched by the NYC Department of Environmental Protection in 2019, led Welde to begin searching for idling trucks. This program allows ordinary New Yorkers to earn a reward for their enforcement efforts.

According to the agency's website, idling gasoline and diesel motor vehicle engines are known to cause health problems such as asthma, respiratory issues, and cardiovascular harm through emissions.

To file and track their complaint, citizen reporters must log on to the city's Idling Complaint System after shooting a video of a commercial vehicle idling for more than three minutes.

The DEP states that the fine for a first-time offender is $350, and it increases for repeat offenders. A 25-percent reduction, or $87.50, is given to the person who recorded the video and submitted the complaint.

Welde stated that he has submitted over 2,000 complaints, which are currently being processed.

Lucrative side hustle

Other clean-air vigilantes, who record idle trucks as a side hustle, include a pediatrician, a former Wall Street banker, and an actress named Rachael Opendaker.

"I can easily get five to six steps within a few minutes while pretending to be on my phone and looking around," Opendaker said to CNBC.

As a pediatrician, Patrick Schnell has made an estimated $36,000 to date. He uses a technique of holding his phone in his hand and trying to be inconspicuous, which works to some extent but not always.

Paul Slapikas, an 81-year-old resident of New York, stated that he has amassed a total of $64,000 without exerting any effort.

Currently, I'm waiting for 42 bounty requests, amounting to $7,300 to be paid, as there are idling trucks everywhere, Slapikas said.

‘Knives pulled on me’

Since the online program began, the city has collected $2.4 million. Citizen reporters have earned more than $724,000 and counting. The Department of Environmental Protection reports that the number of complaints increased by 35% from 9,070 in 2019 to 12,267 in 2021.

Although the program can generate revenue, it may not always be the safest way to quickly earn money.

Slapikas stated that he was threatened with knives three times, yet he never shed a single drop of blood.

The DEP spokesperson states that the city is not liable if a citizen is assaulted while reporting an idling vehicle on a voluntary basis.

Since the program began, former Wall Street banker George Pakenham estimates he has earned approximately $40,000. However, he stated that his participation is not motivated by monetary gains.

“It’s a public health issue,” Pakenham said.

As a medical professional, Schnell, agrees.

Schnell stated that he does it because he observes the severe air pollution, particularly in urban areas with heavy traffic.

In the city, there are approximately 70 inspectors who enforce the noise and air codes, in addition to citizen reporters, as stated by the DEP's spokesperson in an email.

For the clean-air vigilantes, there’s plenty of work ahead.

I won't stop reporting trucks until there's no more idling in New York City," said Welde. "Any commercial vehicle that is not engaged in a process and is parked must turn the engine off.