Open Data Insight of the Day

Fireworks in Basel, particularly on New Year’s Eve and on 1 August, lead to a noticeable but temporary rise in fine particulate pollution. These events release a large amount of fine particles into the air, causing high short-term concentrations. In cold weather or during temperature inversions, these particles can linger, worsening air quality. The Swiss Federal Office for the Environment recognizes this issue, and Basel has already reduced its New Year’s Eve fireworks to show environmental responsibility. Fireworks contribute about 1–2% of Switzerland’s annual particulate pollution, concentrated over just a few days.

In the last two days, we observed a significant increase in PM₂.₅ and PM₁₀ levels, starting in the evening and peaking around midnight. The peak PM₂.₅ concentration reached 77.1 µg/m³, with PM₁₀ at 83.7 µg/m³. These values are considerably higher than the typical levels observed in the days before the fireworks. Figure 1 illustrates the hourly time series of PM₁₀ and PM₂.₅ concentrations, showing the background levels and the sharp peak associated with the fireworks.

Air quality limit values exist to protect public health, with PM10 and PM2.5 regulated differently due to their distinct health effects. The annual limit for PM2.5 is 10 µg/m³, aligning with WHO recommendations. The Swiss air quality standards specify that PM10 should not exceed a 24-hour average of 50 µg/m³ more than three times a year. Despite the clear peak around midnight, the pollution from fireworks is too brief to significantly impact the annual average. Over the past year, the average concentrations were 10.7 µg/m³ for PM₂.₅ and 15.2 µg/m³ for PM₁₀. On the day of the fireworks, the 24-hour mean PM10 concentration was 34.7 µg/m³, which did not exceed the legal threshold. Such exceedances are legally allowed on no more than three days per year.

The measurements at the St. Johann air quality monitoring station capture only part of the actual impact on local air quality. The recorded concentrations depend heavily on wind direction and atmospheric conditions. If the smoke from the official city fireworks does not drift toward the station, the recorded peak may underestimate pollution levels in other city areas. To provide some context, in highly polluted cities like Delhi, India, average PM10 concentrations can reach 190–270 µg/m³, with severe pollution events rising to 400–500 µg/m³ or more. This comparison is meant to illustrate scale and context, not to minimize local impacts. For more information, see Air pollution in Delhi – particulate matter levels.

In summary, fireworks cause clear and measurable short-term air pollution peaks. However, these effects are brief, strongly weather-dependent, and regulated, and they do not substantially influence long-term average air quality.