SmogRank / Episodes / Romania

Romania, Bulgaria and 2 more countries, December 2023

For 2 days, from 1 to 2 December 2023, 10 cities in Romania, Bulgaria, Greece and 1 more countries had PM2.5 at least twice their usual for the time of year. The worst reading was Ruse, Ruse, Bulgaria: 48.2 µg/m³ on 2 December, about 2.8× its usual 17.5. Ended 2 December.

Few fires were detected near these cities on those days. Spreads like this usually come from still weather trapping smoke from heating, traffic and industry, or from dust.
Cities reached10in 4 countries
Days21 to 2 December 2023
Worst day1 December6 cities counted
Furthest above usual3.4×Sofia

Day by day

1 December 6 cities at twice their usual or more
SevlievoGabrovoBaloteştiBotevgradNišCluj-NapocaDejPylaíaKavadarciVelesIlindenPristinaSkopjeTetovoBelgradeBitolaNovi SadThessaloníkiBucharestJilavaHaskovoKochaniHolbocaIaşiRuseCraiovaSofia
28 Nov29301 Dec2345
Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.

How it spread

KochaniKochani, 28 November: 14.2 µg/m³Kochani, 29 November: 15.2 µg/m³Kochani, 30 November: 22.5 µg/m³Kochani, 1 December: 47.4 µg/m³, 2.5× its usual 18.9Kochani, 2 December: 19.0 µg/m³Kochani, 3 December: 16.0 µg/m³Kochani, 4 December: 17.9 µg/m³Kochani, 5 December: 41.8 µg/m³RuseRuse, 28 November: 14.6 µg/m³Ruse, 29 November: 11.6 µg/m³Ruse, 30 November: 20.5 µg/m³Ruse, 1 December: 46.5 µg/m³, 2.7× its usual 17.5Ruse, 2 December: 48.2 µg/m³, 2.8× its usual 17.5Ruse, 3 December: 15.4 µg/m³Ruse, 4 December: 14.6 µg/m³Ruse, 5 December: 27.9 µg/m³ThessaloníkiThessaloníki, 28 November: 38.0 µg/m³Thessaloníki, 29 November: 35.3 µg/m³Thessaloníki, 30 November: 27.3 µg/m³Thessaloníki, 1 December: 46.0 µg/m³, 2.0× its usual 22.5Thessaloníki, 2 December: 40.5 µg/m³Thessaloníki, 3 December: 28.0 µg/m³Thessaloníki, 4 December: 14.7 µg/m³Thessaloníki, 5 December: 22.0 µg/m³CraiovaCraiova, 28 November: 10.1 µg/m³Craiova, 29 November: 8.3 µg/m³Craiova, 30 November: 20.1 µg/m³Craiova, 1 December: 45.7 µg/m³, 3.0× its usual 15.3Craiova, 2 December: 47.2 µg/m³, 3.1× its usual 15.2Craiova, 3 December: 18.8 µg/m³Craiova, 4 December: 11.5 µg/m³Craiova, 5 December: 18.4 µg/m³HaskovoHaskovo, 28 November: 14.5 µg/m³Haskovo, 29 November: 13.3 µg/m³Haskovo, 30 November: 20.3 µg/m³Haskovo, 1 December: 44.4 µg/m³, 2.5× its usual 18.0Haskovo, 2 December: 23.3 µg/m³Haskovo, 3 December: no readingHaskovo, 4 December: 29.9 µg/m³Haskovo, 5 December: 27.8 µg/m³SofiaSofia, 28 November: 11.9 µg/m³Sofia, 29 November: 29.0 µg/m³Sofia, 30 November: 34.4 µg/m³Sofia, 1 December: 30.4 µg/m³, 3.4× its usual 9.0Sofia, 2 December: 4.4 µg/m³Sofia, 3 December: 5.3 µg/m³Sofia, 4 December: 7.8 µg/m³Sofia, 5 December: 5.6 µg/m³IaşiIaşi, 28 November: 14.5 µg/m³Iaşi, 29 November: 14.0 µg/m³Iaşi, 30 November: 19.0 µg/m³Iaşi, 1 December: 24.4 µg/m³Iaşi, 2 December: 43.9 µg/m³, 2.8× its usual 15.8Iaşi, 3 December: 21.8 µg/m³Iaşi, 4 December: 34.0 µg/m³Iaşi, 5 December: 17.6 µg/m³HolbocaHolboca, 28 November: 14.4 µg/m³Holboca, 29 November: 12.5 µg/m³Holboca, 30 November: 14.9 µg/m³Holboca, 1 December: 20.3 µg/m³Holboca, 2 December: 40.9 µg/m³, 2.6× its usual 16.0Holboca, 3 December: 22.6 µg/m³Holboca, 4 December: 34.7 µg/m³Holboca, 5 December: 16.2 µg/m³BucharestBucharest, 28 November: 13.6 µg/m³Bucharest, 29 November: 8.8 µg/m³Bucharest, 30 November: 21.6 µg/m³Bucharest, 1 December: 24.7 µg/m³Bucharest, 2 December: 33.9 µg/m³, 2.2× its usual 15.7Bucharest, 3 December: 13.7 µg/m³Bucharest, 4 December: 11.6 µg/m³Bucharest, 5 December: 15.1 µg/m³JilavaJilava, 28 November: 9.8 µg/m³Jilava, 29 November: 7.4 µg/m³Jilava, 30 November: 16.9 µg/m³Jilava, 1 December: 21.5 µg/m³Jilava, 2 December: 29.6 µg/m³, 2.4× its usual 12.2Jilava, 3 December: 15.7 µg/m³Jilava, 4 December: 12.7 µg/m³Jilava, 5 December: 13.8 µg/m³28 Nov29301 Dec2345
Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
SofiaSofia-Capital, Bulgaria1 30.41 December9.03.4×
CraiovaDolj, Romania2 47.22 December15.23.1×
RuseRuse, Bulgaria2 48.22 December17.52.8×
IaşiIași County, Romania1 43.92 December15.82.8×
HolbocaIași County, Romania1 40.92 December16.02.6×
KochaniKochani, North Macedonia1 47.41 December18.92.5×
HaskovoHaskovo, Bulgaria1 44.41 December18.02.5×
JilavaIlfov, Romania1 29.62 December12.22.4×
BucharestBucharest, Romania1 33.92 December15.72.2×
ThessaloníkiCentral Macedonia, Greece1 46.01 December22.52.0×

Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.

Against other episodes in Romania and Bulgaria

Number 4 of 7 episodes in Romania and Bulgaria since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading.

Use this page

SmogRank, Romania, Bulgaria and 2 more countries, December 2023: 10 cities with PM2.5 at twice their usual or more, 1 to 2 December 2023, smogrank.com/episodes/2023-12-romania-bulgaria-and-2-more-countries (accessed 5 October 2026).

Download top 10 (PNG)

You're welcome to reuse a single chart, image or figure with this citation and a link. Terms.

An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes. Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.