Flu season is upon us, which means it’s germ warfare in the workplace, the marketplace, the nursery school, the classroom and the bedroom.

On Monday, when I got on the packed train, shoulder-to-shoulder with my commuter brothers and sisters, I realized it would be an unpleasant morning because I had a runny nose, a very serious runny nose, along with a wracking cough that was louder than a Guns N’ Roses concert.

This wasn’t an ordinary little cough; it was a phlegm-filled gurgling cough that had the same effect as a pair of fingernails scratching across a blackboard. It transformed my normally sedate fellow commuters into vigilantes who wanted to throw me off the train or lock me in the lavatory to quarantine me.

To make matters worse, I was sitting in the quiet car, making a lot of noise. The sounds of an ailing man — namely me — angered people who didn’t want to get sick and lose a day of work, thereby hurting company productivity and jeopardizing the Obama economic recovery.

In the quiet car, everybody is obsessive about noise, so when I took out a lozenge and tore off the paper, it seemed as loud as a New York City ambulance caught in traffic on Lexington Avenue at rush hour. Then, I reached for my handkerchief to blow my nose, and immediately people near me were cringing in anticipation.

We wouldn’t reach the city for 45 more minutes, so how could I perform this essential task inconspicuously so that the escaping germs wouldn’t spray over everyone? Compounding the misery, I was squeezed against the window by the very large man.

Taking the train during flu season is like being in nursery school. When one toddler has a runny nose, pretty soon everyone shares the pain, right up to the Secretary General of the United Nations.

I'm convinced I caught my cold from a woman who was sitting next to me a week ago and sniffling non-stop. She didn't have a Kleenex, and I was too ashamed to lend her my handkerchief. Doesn't it drive you crazy when people aren’t prepared to deal with a runny nose, especially in public, especially when they’re sitting so close your knees are touching?

Be prepared. That’s my motto even though I was never a Boy Scout. I have three extra handkerchiefs, a bottle of DayQuil, four packages of throat lozenges, including Burt’s Bees honey pomegranate and Halls honey-lemon mentholated, but I don't want to use the Halls because that mentholated smell annoys people as much as cheap perfume.

Looking back, I recall other encounters with germ-infested people recently. I shook hands with a client who informed me ex post facto, “I’m really sick,” which prompted me to rush to the Germ-X dispenser outside the men's room and slather the stuff all over my body. Later, the same fellow blew his nose and shook someone else's hand. Now, the entire town is probably laid up, and company productivity is plummeting everywhere from McDonalds to Merrill Lynch.

Some people take precautions, however. When my friend on the platform heard my raspy voice, he asked, “Are you sick?”

“Yes,” I said, and he moved three steps away and avoided me for the rest of the week. There’s no sympathy. A few days ago a guy went into a 20-minute coughing jag on the train and everyone winced. Some even got up and moved into another car.

Yes, I was struggling not to blow my nose in the interests of peaceful coexistence, but it was a losing battle because the woman in front of me was wearing some kind of nasty perfume that smelled like mosquito repellent, and it felt as if someone was tickling my nostrils with a feather.

In desperation, I cleared my throat, but it wasn’t a benign inoffensive throat clearing that suggested I had a tickle. Instead, it was a very frightening deep throat clearing that trumpeted the warning, “This man is very sick and has a lot of phlegm! Call the EMTs!”

I discovered you just can’t do these things in the quiet car because people get irritated — and there’s no sick car. I expect that pretty soon the conductor is going to announce the new policy — no cell phone calls, no loud conversations, no coughing, no throat clearing and no nose blowing.

Contact Joe Pisani at joefpisani@yahoo.com.