Ex - post evaluation of a program to reduce critical episodes due to air pollution in southern Chile

Highligths

• One-third of the world's population uses highly polluting fuels for cooking, heating, or lighting.

• The main pollution source in southern Chile is the residential firewood combustion.

• This study evaluates the impact of the hourly restrictions on the use of firewood heaters.

• This program is effective in the short term based on the results obtained.

• It is possible to suggest the implementation of this type of program in other cities with similar problems.

Abstract

There is enough scientific evidence that associates air pollution by particulate matter (PM) with negative impacts on health. However, one-third of the world's population uses highly polluting fuels for cooking, heating, or lighting, especially in low- and middle-income countries. Due to the above, the environmental authorities of most of the countries have established different short-, medium-, and long-term regulations to reduce this pollution. It should be noted that it is challenging to identify the real effectiveness of this type of regulation since it is necessary to determine whether the pollution was reduced exclusively by the implementation of that regulation or due to other confusing factors. To address this issue, the present study performs an ex - post evaluation of the Critical Episodes Management program that imposes restrictions on the use of firewood heaters during pre-emergency and emergency episodes to reduce air pollution in the short-term in the city of Temuco, Chile (one of the most polluted cities in Latin America). Specifically, a fixed-effects panel data regression is applied to hourly concentrations of particulate matter data, controlling by meteorological and seasonal factors. The results show that restrictions on the use of firewood heaters generate a significant reduction in PM₁₀ and PM_2.5 concentrations during pre-emergency episodes (9.2% and 17.5%) and emergency episodes (5.9% and 16.3%). Thus, it can be concluded that this program is useful, but it must be complemented by others medium- and long-term environmental programs.

Introduction

Residential combustion of firewood used for heating causes a variety of dangerous chemical compounds, among which breathable particulate matter (PM₁₀) and fine particulate matter (PM_2.5) stand out (Plejdrup et al., 2016; Samburova et al., 2016). The presence of particulate matter in the air affects the health of the population because it can be inhaled and penetrate the respiratory tract causing an increase in premature mortality (Huang et al., 2018; Zhang et al., 2018; Maji et al., 2017; Song et al., 2017), lung cancer (Lepeule et al., 2018; Shahadin et al., 2018), respiratory and cardiovascular diseases (Kim et al., 2017; Maji et al., 2017). For this reason, in Chile as in other countries, some standards set limits for the environmental concentration of these pollutants.¹

According to Gordon et al. (2014), one-third of the world's population uses highly polluting fuels such as firewood or coal for cooking, heating or lighting, especially in low- and middle-income countries. The pollution by firewood heating is an environmental problem that affects mainly geographical areas where firewood is abundant, and there are low temperatures during the autumn-winter season. Some studies have shown this problem in areas of Denmark (Glasius et al., 2006), Chile (Mardones and Saavedra, 2016; Alegría et al., 2013; Chávez et al., 2011), United States (Allen et al., 2011), New Zealand (Wang and Shooter, 2002), Australia (Keywood et al., 2000), Bangladesh (Dasgupta et al., 2006), India (Balakrishnan et al., 2004), among others.

In southern Chile, there is a strong cultural preference for the use of firewood to heat houses during autumn and winter; this is because of the abundance of biomass and its low price compared to other fuels (Schueftan and González, 2018). According to Reyes et al. (2018) the use of firewood has increased in Chile. However, to replace firewood by fossil fuels could increase energy poverty levels (Reyes et al., 2015). Specifically, the primary source of pollution in the city of Temuco² is the residential combustion of firewood (See Fig. 1). For this reason, this city is considered an exceptional case of pollution by a single type of emitting source (Cereceda-Balic et al., 2012).

Additionally, the city of Temuco is classified as one of the most polluted cities in Latin America by the World Health Organization (WHO). Therefore, in 2010, a decontamination plan was implemented to reduce PM₁₀ concentrations in the medium- and long-term; the plan included different measures and programs such as subsidies to replace firewood heaters by others more efficient, foments instruments for dry firewood commercialization, subsidies for the thermal houses reconditioning, more exigent thermal standards for new houses constructions, among others. Subsequently, the decontamination plan was updated in 2015 to also regulate the PM_2.5 (Ministry of Environment, 2015).

In 2013, a program for the Management of Critical Episodes (GEC in Spanish) was also launched in the context of the Decontamination Plan for the city of Temuco; this includes prevention and mitigation measures that are quickly implemented to face in the short-term the days of critical episodes due to high pollution. The use of more than one firewood heater per house in an environmental pre-emergency episode is prohibited, and the use of firewood heaters in an environmental emergency episode is totally prohibited.³ This type of regulation is not permanent since low-income households that regularly use firewood for heating could hardly afford the higher cost of alternative fuels such as gas, kerosene or electricity, so during the restrictions, they often have to deal with low temperatures inside their poorly isolated houses (Schueftan and González, 2013).

On the other hand, the ex-post evaluation of environmental policies includes a set of methodologies that seek to determine with different identification strategies whether an environmental objective is fulfilled exclusively due to the application of a program or by other external factors. For example, Chay and Greenstone (2003) use the instrumental variable method to estimate the impact on changes in infant mortality in the first year of the Clean Air Act in the United States. Greenstone (2004) uses the propensity score matching method to evaluate whether the Clean Air Act and its subsequent modifications contribute to the decrease in the environmental concentrations of sulfur dioxide. Giovanis (2014) evaluates whether the ozone smog alerts of the voluntary “Clean Air Works”⁴ program are effective, for which a quadruple differences estimator is applied. Li et al. (2017) use a time-series regression discontinuity method to determine if reforms in the environmental management strategy and emission control generate a substantial short-term improvement in air quality in Beijing. Chen et al. (2013) use the differences in differences method with panel data to study the effects of the implementation of a series of radical measures to improve air quality during the 2008 Olympic Games in Beijing. Calzada and Sanz (2018) apply the propensity score matching method to evaluate the effects of a program that subsidizes the replacement of traditional firewood heaters with gas stoves in Peru. Mullins and Bharadwaj (2015) apply a matching with differences in differences to determine whether temporary restrictions on days when poor air quality is predicted help to reduce air pollutant concentrations and reduce negative health impacts in the short-term in Santiago, Chile. For this, they match each environmental episode day with similar days in which an episode was not predicted, concluding that there is in the short-term a reduction of approximately 20% in PM₁₀ concentrations when environmental episodes are decreed.

Herrick and Sarewitz (2000) remark the importance of ex-post evaluations in the formulation of environmental policies. Ex-post evaluations do not seek to replace ex-ante evaluations, but rather their objective is to identify the effect that can be attributed exclusively to a policy or program; therefore they are useful for improving the assumptions used to perform ex-ante evaluations.

According to the above, this study seeks to determine the effectiveness of prohibitions on the use of firewood heaters during critical episodes (GEC program) in the city of Temuco, Chile. Fortunately, to implement the identification strategy in this ex-post evaluation, there are historical data on hourly concentrations of particulate matter in monitoring stations located in zones with and without prohibition for the period prior and following to the implementation of the program, which makes it possible to apply a regression of panel data with fixed-effect.⁵ The effectiveness of this program could have a meaningful impact on the environmental policy of other countries since it allows determining the real contribution of regulations to face high pollution events in the short-term. Besides, this study case is almost unique and difficult to replicate in other areas without proper prior planning. This is explained because environmental regulations usually apply to the entire area affected by pollution, but in this particular case, the existence of an affected area without regulation allows obtaining a great counterfactual scenario to carry out this ex-post evaluation.

It is important to remark that in the previous literature there have been ex-post evaluations for various types of environmental regulations, which include vehicle restrictions (Gallego et al., 2013; Cao et al., 2014), voluntary programs (Mardones and Bienzobas, 2019; Blackman et al., 2010), regulations at national level (Greenstone, 2004), regulations in specific areas (Tanaka, 2015), environmental taxes (Jaraite et al., 2014), among others. However, the original contribution of this study is to evaluate the effectiveness of a temporary regulation on residential sources that presents severe enforcement difficulties due to a large number of small emitting sources, the high compliance costs (associated with replacing fuels) and that at the same time benefits the same regulated sources through quality improvement of the air they breathe. Thus, determining the overall impact of these conflicting incentives on economic agents that are simultaneously regulated and benefited is of interest to environmental impact assessment literature, environmental economics, or policy studies.