Minimizing Health Impacts of Urban Air Pollution

By Claire Halloran

As cities develop and their populations grow, urban officials must develop comprehensive plans to address a variety of air pollutants, including gases and particulate matter, from a vast array of sources. The magnitude of health damage caused by air pollution necessitates both short-term protective measures and long-term solutions to the problem of urban air pollution. Due to the variance in pollutant sources by region and level of economic development, these plans to minimize air pollution must be tailored to each city.¹

The feasibility of solutions must be evaluated through case studies of cities. Many innovative solutions are not cost-effective or scalable for implementation in large urban areas. Economic development and cultural differences determine which solutions are viable in various cities. In this article, the air pollution problems and solutions of Berlin and Beijing are examined in detail.

Short-Term Solutions: Temporary Protection

Short-term measures can be widely implemented in the next five years to reduce exposure to air pollution in highly polluted cities. While these measures are generally temporary fixes to protect people from current air pollution levels, they are vital in many areas where pollution levels exceed the WHO standards and cause serious health problems. These solutions may also be necessary for people with respiratory diseases who live in urban areas, even if pollution levels do not exceed the WHO standards.

In the developed world, people spend about 90 percent of their time indoors, so individuals can easily limit their exposure to pollution by ensuring that their indoor air is clean.² Ensuring indoor air has a relatively low concentration of particulate matter is highest priority given the vast array of serious health issues with which it is associated. Particulate matter can be removed from indoor air using portable filters and filters incorporated into HVAC systems.² Such filters are extremely cost-effective: the estimated monthly cost per person is approximately 0.70 to 1.80 in 2001 US dollars.³ Implementation of such filters in schools and businesses in Berlin, with a population of 3.5 million people, would cost between $2.45 million and $6.3 million (in 2000 USD).⁴ The much larger city of Beijing, with a population of 11.5 million in 2000 (the last year UN data is available), would have to spend between $8.05 million and $20.7 million for the same program.⁴ The penetration of particulate matter into buildings can further be reduced at reducing the indoor-outdoor air transfer in buildings; for instance, closing windows has been shown to reduce air exchange rates by 50 percent.² Such solutions could be implemented at negligible cost in buildings with developed infrastructure; however, cities in tropical areas may have more open concepts that make this difficult, and people in informal settlements may not be able to control airflow into their home.

Governments can empower individuals to limit their exposure to air pollution further by implementing public air quality alert systems. Such systems allow people who are especially susceptible to adverse health effects from air pollution, including those with chronic cardiovascular or pulmonary disease, children, and the elderly, to stay indoors and limit their physical exertion.² While many such alert systems, like airnow.gov in the United States, exist, they must be made more urgent and widely available since most people currently adjust their behavior based on personal perception of air quality, not official alerts.² Governments can increase awareness of air quality alert systems by incorporating the warnings into a mobile application similar to worldaqui.com and posting them on billboards or other prominent locations in the city for relatively little cost. While creating a system of air quality alerts is somewhat more costly, many cities and other governments have established such systems that could be used as templates. However, the effectiveness of these alerts depends upon the individual actions they inspire, which may not be effective in preventing health problems. Recent research suggests that public health alerts for susceptible groups, such as those with COPD (chronic obstructive pulmonary disease) and asthma, increase health service utilization for respiratory conditions.⁵ This result indicates that air quality alerts may make people more aware of poor air quality but not cause them to avoid outdoor air. Rather, it seems people are more conscious of poor air quality and thus more likely to seek medical treatment if they experience respiratory problems. Although this is not the intended effect of air quality alerts, it may be beneficial for people sensitive to low air quality to seek medical attention. Limiting outdoor physical exertion during high pollution periods is somewhat effective in reducing air pollution intake because the nose is more effective at filtering particles and water-soluble gases than the mouth, which is used in periods of heavy physical activity. However, the cardiovascular and respiratory benefits of exercise may exceed the adverse effects of air pollution.² Therefore, the benefits of limiting physical exertion vary from case to case, and individuals susceptible to adverse health effects from air pollution consult individually with a physician.²

Cities can also help pedestrians and cyclists minimize their air pollution intake by providing low-emissions zones for exercise and emission-free transportation.² In these zones, vehicles may be either completely banned, forced to comply to strict emissions requirements, or forced to purchase permits from the city, which could make this solution cost-effective. If such drastic measures are not politically or economically viable, cities could develop websites and mobile applications to assist people in finding biking and walking routes that avoid high-pollutant areas.² A substantial amount of a person’s air pollution intake occurs during the daily commute in vehicles, so motorists can reduce their intake of pollutants by minimizing their driving time, traveling during low traffic volume times, keeping vehicle windows closed, and recirculating cabin air.² Cities may decrease traffic during high-volume times by disincentivizing travel during these times with higher tolls. While such a system would require an initial investment in areas without pre-existing tolls, cities could eventually profit from the increased tolls. Motorist themselves can easily plan their commute during low-volume times and take low-volume routes using existing GPS services and their knowledge of city traffic.

In urban areas with severe air pollution, people may wear personal respirators to minimize their exposure to air pollution; however, no combinations of adsorbents in personal respirators can effectively remove all types of air pollutants. Furthermore, the need for individual fitting of respirators renders their widespread use outside of industrial settings highly impractical.²

Long-Term Solutions: Making Cities Breathable

The limited effectiveness and viability of short-term solutions necessitates comprehensive long-term solutions to minimize the adverse health effects of urban air pollution. Especially as cities continue to grow, local officials must develop methods of ensuring that urban areas are livable for the future.

Urban transportation improvements have the potential to significantly mitigate the adverse health effects of air pollution. As shown in Figure 1, traffic accounts for an average of 25 percent of urban particulate matter, the most lethal form of air pollution.¹ In addition, traffic has become an increasingly important source of air pollution as limits on industrial air pollution reduce the relative contribution of industry to air pollution in most developed areas.² City officials can reduce air pollution from transportation by improving transportation infrastructure, increasing accessibility to public transportation, increasing public transportation efficiency, and encouraging alternative transportation methods rather than personal vehicle use. Given the popularity of personal vehicle use in many regions, expectations that personal vehicles will be completely eliminated are unrealistic. Instead, personal vehicles with lower emissions, such as hybrid and electric cars, and higher efficiency, such as shared cars, should be improved and used more widely.

Figure 1. Relative contribution of sources of particulate matter in urban areas worldwide. Improving the efficiency of transportation and promoting transportation methods that don’t produce emissions can significantly improve urban air quality, as traffic accounts for 25 percent of particulate matter concentration on average. ¹

However, the contributions of the sources in the figure above are averages and vary greatly by region, so urban areas should evaluate their own sources of air pollution and customize plans to minimize their pollution.¹ In most places, policy limiting the contribution of predominant sources of air pollution must be combined with technology that meets the needs of urban areas while simultaneously protecting citizens’ health.

Real-World Cities: Applying Proposed Solutions

To examine the efficacy and costs of applying the solutions proposed in the previous section, this section discusses the air pollution problems of several real-world cities and their success in applying solutions, as well as recommending further action.

Case Study: Berlin

Despite success improving air quality in recent decades and being ranked highest among European cities for combating air pollution in 2011, Berlin has recently had difficulty decreasing air pollution, especially nitrogen oxides and particulate matter.^6–8 Compared to the rest of Western Europe, Berlin has very poor air quality and one of the highest concentrations of nitrogen dioxide.⁸ This nitrogen dioxide emission is primarily due to motor vehicle traffic, despite substantial government efforts to reduce traffic and encourage bicycling.⁸

Since 1989, Berlin has significantly reduced its emissions (see Figure 2). There were both environmental and economic imperatives for improving air quality: according to a 2000 EU estimate, health problems from air pollution cost Western Europe between 277 and 790 billion euros a year.⁷ Berlin has had particular success in reducing its sulfur dioxide emissions for domestic heating by divesting from brown coal and using pipeline-based energy sources, such as natural gas, instead.⁶ Lethal particulate emissions from car exhaust also decreased by 80 percent over this time period; however, cars remain the second largest source of particulate emission, contributing 29 percent of PM₁₀ and 32 percent of PM_2.5.⁶ Because of the vast array of significant health effects that particulate matter causes, reducing particulate matter concentrations by decreasing vehicular emissions is high priority. As shown in Figure 3 motor vehicles also became a more significant source of pollution by replacing industrial plants as the main source of nitrogen oxides.⁶

Figure 2. Improvement in Berlin’s emission from 1989 to 2009. There was a marked decrease in all emissions, particularly sulfur dioxide levels, which are now stagnant at low levels.⁶

Motor vehicles continue to be a problem for air quality in Berlin. In 2011, Berlin was ranked highest of European cities for combating pollution in recognition of its efforts to reduce car use.⁷ Berlin was the first city to implement a low emissions zone (LEZ), which banned cars with high emissions from a certain area and required registration for diesel engines and retrofitting with particle filters for older vehicles.⁸ Although this program has administrative costs, Berlin can also profit from vehicle registration fees. Berlin also promoted biking and walking through bicycle and pedestrian-friendly infrastructure at an estimated cost of 15 million euro annually.⁹ Clearly, this costly program would not be viable in areas where air quality is not a cultural priority or the government lacks the resources for such infrastructure projects. This program seems to have had some success: trips by bike increased by 51 percent from 2001 to 2014, and Berlin has 350 vehicles per 1000 residents, significantly lower than the German average of 600 per 1000.⁸ However, despite lower car ownership and increased bike trips and use of public transportation, the number of cars in Berlin increased from 1.21 million to 1.35 million from 2006 to 2012.⁸ It seems that the number of commuters and visitors in Berlin is increasing or that Berliners may be using their cars more on average.⁸ This failure suggests the need for decreasing urban traffic directly through measures similar to London’s congestion charge zone, which decreased car traffic by 15 percent and lowered nitrogen dioxide levels by 7 percent.⁸ However, the strength of the automobile industry in Germany makes political action to disincentivize car use and ownership extremely difficult.⁸

Figure 3. Motor vehicle traffic has become the most important source of nitrogen dioxide emissions in Berlin. Reducing motor vehicle traffic is also important in decreasing the concentration of particulate matter, the pollutant with the most serious health effects.

Although Berlin has made great strides in improving air quality since 1989, the city is struggling to combat the powerful automobile industry and the cultural preference for cars to limit nitrogen dioxide emissions. Despite the great costs of its programs to promote bicycling and walking and the pioneering low emissions zone, Berlin is struggling to make progress in lowering emissions to match its Western European peers.

Case Study: Beijing

In contrast to Berlin, Beijing is infamous for high levels level of air pollution. In terms of public health problems, the most important metric is particulate matter concentration, and Beijing has one of the highest concentrations worldwide.The city’s fine particulate matter levels are usually around 300-400 ppm (parts per million) during the winter, well above WHO recommendations.¹⁰ Citizens are aware of the issue, and attempts at short-term prevention methods are commonplace: people often wear masks to protect against health effects of air pollution, and most schools don’t have air purifiers, so teachers open classroom windows for “fresh air” (this misconception highlights the importance of education about air pollution).¹⁰ The need for government action on this issue is a widespread idea among the Pekinese, and the government has responded by reducing China’s overall emissions by 6 percent, according to the National Development and Reform Commission, and by creating a color-coded air quality index.¹⁰ However, this emission reduction has little noticeable impact for the average Chinese family, and red alerts on the color-coded scale are rarely issued in Beijing, despite fine particulate matter levels frequently being well over the threshold.¹⁰ In such a case where the government fails to inform the public about air quality, NGOs should independently evaluate air quality and inform the public of their results. China has also vowed at the Paris climate talks to reduce carbon emissions by 2030, increase the use of renewable fuels, and grow 4.5 million m² of new forest area.¹⁰ These measures should noticeably improve air quality: renewable fuels have significantly less emissions, and forests act as natural air filters for carbon dioxide and particulate matter.¹¹ Government follow-through on such promises are crucial for protecting the respiratory and cardiovascular health of Pekinese.

Looking Ahead: Clean Air by 2050

As urban population increases worldwide, city officials must take measures to protect increasingly large numbers of people from the adverse health effects that air pollution causes. However, urban air pollution is already a large problem for millions of people in cities worldwide, so short-term measures are needed to protect current urban populations. Temporary solutions such as indoor air filters, air pollution level alerts, and personal respirators offer some protection from high air pollution levels, but long-term action is needed to ultimately reduce air pollution emission to make urban living healthy. The costliness of temporary solutions for cities, on the order of magnitude of millions of euros or dollars for each solution, and the cost of health problems caused by air pollution further encourage the development of permanent solutions to low air quality. Permanent protection against the adverse health effects of air pollution requires a combination of technology and policy. Alternative processes for energy production, transportation, and industrial processes with fewer emissions must be developed, and policies must be implemented to reduce air pollution, especially in pedestrian- and cyclist-heavy areas. In this way, cities can ensure that they provide a healthy environment for their growing populations.