Weekend-Weekday Effect Assessment for O3, NOx, CO and PM10 in Andalusia, Spain (2003-2008)

Abstract

Day-of-week variations in O 3 , NO x , CO and PM 10 were analysed in the southwestern region of Europe (specifically Andalusia, Spain) using hourly concentrations collected at 43 stations (representing five typologies) over 6 years (2003)(2004)(2005)(2006)(2007)(2008). This area has air pollution problems, and the study of the weekend effect is used as a tool to plan future strategies for emissions reductions. Maximum daily 8 h averages for O 3 , daily 90 th percentiles for NO, NO 2 and PM 10 and mean daily values for CO were calculated and used to assess the weekend effect by applying three different metrics: weekly evolution, weekend-weekday differences and average daily difference between weekends minus workdays. Based on daily parameters and weekend-weekday differences, all the measured air pollutants exhibited clearly reduced concentrations (oscillating between 25 to 85%) on weekends, mainly at urban and suburban stations, with the exception of O 3 (less than 10 µg/m 3 ). This decrease on weekend days was mostly observed for NO, NO 2 and PM 10 at urban stations, while differences at industrial and rural stations were low or null. CO showed a low reduction. Using the daily cycle of differences (weekend minus workdays) as a reference, positive deviations were observed at night and negative differences were observed during the daytime for NO, NO 2 and PM 10 at urban traffic, urban background and suburban background sites. A reduction in morning rush hour traffic during the weekends was reflected in the data from urban stations, which showed a decrease of up to 50, 15 and 12 µg/m 3 for NO, NO 2 and PM 10 , respectively. An opposite daily behaviour was found for ozone, which showed an increase at urban area sites of up to 15 µg/m 3 in the early morning.

ANALYSIS OF NOX, NO AND NO2 AMBIENT LEVELS AS A FUNCTION OF METEOROLOGICAL PARAMETERS IN DHAHRAN, SAUDI ARABIA

“…It is well known that ozone level in early morning is low and increases considerably at midday, attains its maximum in the afternoon and decreases during night [19]. There is a strong correlation between ozone and ultraviolet flux from solar radiation, with maximum level of ozone attained about 1 to 2 hours after UV flux maximum [1].…”

“…Therefore, weekend-weekday effect for NOx concentrations in Dhahran during the study period from 07 May to 30 July is not significant. It should be noted that the mechanism for the weekend behavior observed in many cities, until now is not well understood [1], [19], [21]. Table 1 shows the correlation coefficients between hourly NO, NO2 and NOx concentrations and the measured meteorological parameters.…”

On the concentration and size distribution of sub-micron aerosol in the Galápagos Islands

“…The SCR-PBM sampling site is located in an urban site and close to a forested area and therefore both anthropogenic and natural particle contributions to the observed particle concentrations can be expected. The concentration of primary particle pollutants shows weekly patterns, reflecting the day to day variations of the anthropogenic emission activities (Adame et al, 2014). In urban areas, the decrease of human activity during weekend days, which was corroborated 'in situ' during the campaign, produces lower emissions, and therefore lower particle concentrations.…”

Evaluating Mitigation Plans over Traffic Sector to Improve NO<sub>2</sub> Levels in Andalusia (Spain) Using a Regional-Local Scale Photochemical Modelling System

“…The effect of mitigation plans over ozone depends on the kind of area (urban, suburban or rural), on the effect over volatile organic compounds (VOCs) emissions of every measure, and on the weekend effect. This phenomenon refers to the weekly behaviour shown by surface ozone concentrations in urban atmospheres, in which a reduction of the levels of its precursors (nitrogen oxides and volatile organic compounds) during the weekend carries an increase of ozone concentrations [43]- [45].…”