Lima is one of the most highly polluted cities in the Americas (WHO (World Health Organization), 2016). Silva et al., (2017) reported that between 2010 and 2015, the average annual concentrations of particulate matter with diameter < 10 µm (PM10) and < 2.5 µm (PM2.5) were 84 and 26 µg/m3, respectively. They found that PM2.5 concentrations at six of the ten regulatory monitors in Lima exceeded the World Health Organization (WHO) daily guideline on 77% of the days between 2014 and 2015. PM2.5 concentrations in Lima show seasonal trends, with the highest levels observed in the summer (Romero et al., 2020b).
Epidemiologic evidence has found that air pollution was responsible for 2,300 premature deaths due to cardiorespiratory disease in Lima adults every year between 2001–2011 (Gonzales and Steenland, 2014). Tapia et al., (2020) found that between 2000 and 2016, an interquartile range increase in PM2.5 was associated with a 4% increase in respiratory emergency room (ER) visits. There is thus an urgent need to reduce pollution levels in Lima.
Vehicular emissions are the dominant source of pollution in the city (Arias Veĺasquez et al., 2019; Silva et al., 2017). The diurnal peaks of PM2.5 during rush hours (Romero et al., 2020b; Sánchez Ccoyllo et al., 2011), as well as the association between proximity to roads and the concentrations of PM2.5 and Black Carbon (BC) is evidence of this (Underhill et al., 2015). The government has attempted to mitigate vehicular pollution by phasing out lead from gasoline, reducing the sulfur content in diesel and reducing the permissible age of vehicles. However, despite these efforts, the number of vehicles in the city is rapidly increasing. Between 2000 and 2014, emissions from registered vehicles in the Lima Metropolitan Area (LMA) increased by almost 65%. In 2019, Lima had a fleet of more than 2.7 million motor vehicles, that has been projected to grow at 7% per year (C. Posada, 2018). The average age of Lima’s vehicular fleet exceeds 15 years for private vehicles and 22 years for public transport vehicles (BBVA, 2010), and thus the emissions from an average vehicle is much higher than a typical vehicle in the developed world. It is exceedingly important to develop effective transportation policies to reduce vehicular emissions.
To this end, research has been undertaken to understand the spatially disaggregated impact of vehicular emissions (Romero et al., 2020a, c). Such analyses can inspire the development and implementation of targeted policies to reduce emissions. Other crucial research has examined the impact of traffic regulations on certain main avenues in Lima on air pollution (Morales-Ancajima et al., 2019). More work is needed to evaluate existing transportation policies on air pollution, so that they can be fine-tuned.
In 2019, Lima hosted the XVIII Pan- and Parapan- American Games (Games) (July 26-September 1). A major concern before and during this event were the traffic and high levels of pollution that could potentially affect the athletes. Therefore, the Peruvian government, in collaboration with regional authorities, adopted a variety of traffic control actions just before and during the Games. Most of these policies were discontinued after the end of the Games except for the pico y placa policy, which continued until mid-2020, when it was temporarily halted due to the COVID-19 emergency in the city. In this article, we evaluate the impact of the pico y placa policy on PM2.5 concentrations in Lima using a difference-in-difference methodology.