Q: I often feel under siege when bombastic missionaries preach fire and brimstone on the train. Is this legal?

A. Preaching on a subway car is illegal. The “solicitation for religious or political causes … public speaking; distribution of written non-commercial materials” as well as “artistic performances” are illegal on subway cars, according to section 1050.6 of the Metropolitan Transportation Authority’s Rules of Conduct. It is within your right to ask a person engaged in these activities to stop or to notify the authorities. The rules change when not on a bus or subway car. On a platform, for example, the activities mentioned above are legal as long as individuals do not use sound equipment or tables. Selling goods for profit is illegal anywhere in the transit system. Asking for donations is also illegal on a subway car. Thus, people who ask for donations or individuals who purport to collect money for homeless people, for example, are doing so illegally – and most likely fraudulently – while roaming from one subway car to the next.

Individuals representing organizations are allowed to solicit donations on a platform, however, under certain conditions. Anyone who says they represent a nonprofit must be able to show they are registered as a charitable organization in New York, are exempt from federal income tax under Section 501(c)(3) of the United States Internal Revenue Code, and have been licensed by the city to solicit donations within the past 12 months. For anyone looking to confront people engaged in illegal activity, this phrase in the rules of conduct may embolden you: “Solicitors for such charities shall provide, upon request, evidence that such charity meets one of the preceding qualifications.”

The no. 4 train this week has been bone-chillingly cold. What temperature are the trains’ air conditioners set at and who monitors them?

Air conditioners on every train are set between 71 and 73 degrees, a spokeswoman for New York City Transit, Deirdre Parker, said. The variables that affect a car’s temperature range from how old the car is, how long its doors remain open at a stop, how many people are on the car, and whether it’s on an elevated track or underground, since tunnels are generally much warmer in the summer than outside temperatures. No. 4 trains are the newest trains in the system and therefore have the best working air conditioners. They are designed to turn on when the temperature in the car rises above 73 degrees and the outside temperature is greater than 50 degrees, Ms. Parker said. If the temperature drops below 71 degrees the air conditioners are supposed to switch off and circulate non-chilled air through the car. The two roof-mounted units blow the conditioned air through a vent that runs diagonally across the car, intended to direct cold air toward the car’s center. Thus, Ms. Parker recommends standing at the ends of the car to avoid the coldest spots.