WARSAW — Michal Czekala’s job chopping down trees keeps the 21-year-old out in the fresh air pretty much all day long. But after hearing news recently that the air was far from fresh, that in fact ­record-high smog was enveloping the entire nation, he decided to take a week off work.

“There’s no telling what could happen to me in this smog,’’ he said recently as he and a friend drifted out of a movie theater in Targowek, one of the Warsaw districts hardest hit by the high pollution levels.

An eerie gray mist with a pervasive odor of fumes wreathed Warsaw and dozens of other Polish cities, bringing a global problem more associated with Beijing and New Delhi into the heart of Europe. It took less than half a day, on Jan. 8, for the smog levels to break all records set in the 10 years since Poland, following a directive from the European Union, put in place an air pollution monitoring system.

Warsaw city officials reacted by making all public transportation free last Monday, in an attempt to keep cars off the roads and warned residents to stay indoors unless necessary. Pollution levels eventually dropped off toward the end of the week.

The surge in pollution came shortly after a report by the World Health Organization said that 33 of the European Union’s 50 most polluted cities are in Poland, which relies heavily on its cherished national coal industry and bluntly refuses to invest in renewable energy sources that might supplant coal, known here as black gold.

The issue, though, is not just cars and coal. Warsaw’s spike in air pollution was driven largely by a severe cold snap that forced thousands of private households, especially the most destitute ones, to crank up poor-quality heaters that burn things like coal and garbage to beat back the winter chill.

“Eighty percent of all households in Warsaw are connected to a district heating network,’’ said Michal Olszewski, deputy mayor of Warsaw. “The problem is the remaining 20 percent that often use these low-tech heating systems.’’

According to Poland’s Central Statistical Office, this could be the case in more than 150,000 households in a city with 1.7 million residents.

The situation got out of hand in the first week of January after a Siberian blast poured into the region and temperatures dropped below zero degrees. People overworked their heaters, and an absence of wind caused the smog to squat gloomily over the capital.

For most of three days, according to data collected by the Regional Inspectorate for Environmental Protection in Warsaw, air quality in the city was either “bad’’ or “very bad,’’ meaning the entire population was likely to be affected, and some people could have experienced serious health effects.

On average, readings of fine particulates in the air exceeded Polish environmental norms by fourfold, at some points reaching 1,000 percent of the norms.

But this may well understate the problem. Ilona Jedrasik from ClientEarth, a nonprofit environmental law organization, said some air pollution monitors in the region simply stopped working because of the high concentration of pollutants.

High smog levels, Warsaw authorities warned, could be especially dangerous for children, older residents, pregnant women, and people with existing health issues.

The health consequences of such a high level of pollutants in the air can be severe, including failure of the respiratory and circulatory system, heart attacks, and strokes. In fact, the European Environment Agency estimated last year that bad air was responsible for almost 45,000 premature deaths a year in Poland.

Magdalena Urban, a 25-year-old marketing specialist in Warsaw, said Monday evening that she had been suffering from a headache since the day before.

“It hurts around the temples, and I’m constantly feeling nauseated,’’ Urban said as she went grocery shopping in Zabki, a town just outside the capital. “I’m going out shopping because I don’t know what else to do. This has all been so sudden.’’

Beata Szydlo, the prime minister, said Monday that her government was going to work on ways of reducing a problem that “is so very burdensome for the Polish citizens,’’ though she did not provide any specifics.

Health Minister Konstanty Radziwill caused controversy at the beginning of the year — before the pollution levels radically increased — when he called the smog “a theoretical problem’’ and said that “there are no reasons for panic,’’ and besides, “our lifestyle is much more damaging.’’

“Someone who breathes in air smoking a cigarette, with fumes and everything that comes with it, is in a position in which complaining about poor air quality is not credible at all,’’ Radziwill told a private radio station, Tok FM.

However, according to estimates by Warsaw Without Smog, an environmental group, residents of the capital inhale the equivalent of a thousand cigarettes a year. It is even worse in the towns on the outskirts of Warsaw, where people breathe in an equivalent of up to 2,400 cigarettes a year, or 6½ a day.

Agnieszka Drozd, an activist with another environmental organization, Warsaw Smog Alarm, said that “no one is exempt from this damage.’’

“Think of your children smoking a couple of cigarettes a day,’’ she said. “It’s that bad.’’