The Smoky Haze Of La's Air Pollution

Los Angeles, California, is notorious for its smog and air pollution, which is caused by a combination of particle and ozone pollution. The city's unique geography, surrounded by mountains, traps air pollution and prevents it from dispersing. Wildfires, hot summers, and strong winds also contribute to the air quality issues in the region. The burning of fossil fuels, vehicle emissions, and industrial processes further exacerbate the problem. Despite improvements in recent decades, Los Angeles still struggles to meet national air quality standards, and the health implications of air pollution are evident, with increased risks of asthma, cancer, and other respiratory issues.

LA's air pollution is the worst in the US

Los Angeles is notorious for its smog, a combination of particle and ozone pollution. The city's unique geography, surrounded by mountains, makes it especially susceptible to air pollution. The warm, dry conditions, highly flammable vegetation, and strong Santa Ana winds also contribute to the frequent occurrence of wildfires, which further degrade air quality.

According to the 2019 State of the Air report, Los Angeles has the worst ozone air pollution in the United States. Ozone is a harmful gas that is formed when sunlight reacts with nitrogen oxides and organic substances. Vehicle emissions, power plants, and refineries are significant contributors to the formation of ozone. Traffic is frequently identified as a leading source of ozone pollution, and with 6.5 million vehicles in the city, it's no surprise that Los Angeles struggles with air quality.

The health implications of poor air quality in Los Angeles are evident. According to the County of Los Angeles Public Health Department, one in ten children has been diagnosed with asthma. The overall risk of cancer also increases due to air pollution. Fine particle pollution, or PM2.5, has been linked to respiratory illnesses, heart disease, and even premature death. The greater Los Angeles county contains nine of the 15 most polluted cities in the United States in terms of PM2.5 levels.

While Los Angeles has made significant improvements in air quality over the last three decades, it still has a long way to go to meet the U.S. EPA's national air quality standards. The Clean Air Act and its subsequent amendments have been instrumental in reducing air pollution, and local and state regulations continue to push for emission reductions, particularly in the transportation sector.

LA's basin traps air pollution

Los Angeles, California, is notorious for its poor air quality. The city's unique geography, a basin surrounded by mountains, is conducive to trapping air pollution. This is further exacerbated by the region's temperature inversions, where warm air from the Great Basin or inland Los Angeles traps cooler ocean air close to the Earth's surface, a phenomenon known as a marine inversion.

The marine inversion acts like a lid on a pot, trapping pollutants and preventing them from rising and dispersing. This results in the accumulation of particle and ozone pollution, commonly referred to as smog. The prevalence of these pollutants is influenced by various factors, including the burning of fossil fuels, vehicle emissions, industrial processes, and wildfires.

Wildfires play a significant role in impacting the yearly average air pollution in Los Angeles. The combination of dry conditions, flammable fuels, hot summers, steep mountains, and strong winds creates an ideal environment for large and severe wildfires. The smoke and emissions from these fires can fill the LA Basin, and the region's geography makes it challenging for the air pollution to disperse, leading to slowly accumulating pollution levels.

In recent years, Los Angeles has made significant improvements in air quality. The implementation of the Clean Air Act and its amendments, along with local and state regulations, have contributed to reducing emissions and improving air quality in the region. However, despite these efforts, Los Angeles County still falls short of meeting the U.S. EPA's national air quality standards for several pollutants, including particulate matter, ground-level ozone, lead, carbon monoxide, nitrogen oxides, and sulfur oxides.

The health implications of air pollution in Los Angeles are evident, with increased risks of asthma, cancer, and other respiratory and cardiovascular issues. Addressing air pollution in Los Angeles remains a critical priority to mitigate the adverse effects on the climate and the well-being of its residents.

Wildfires increase air pollution in LA

Los Angeles, California, is notorious for its smog, a type of air pollution resulting from particle and ozone pollution. The prevalence of these pollutants is caused by several factors, including the burning of fossil fuels, especially by vehicles, ships, planes, and manufacturing, as well as wildfires.

Wildfires in Los Angeles are often fuelled by strong, dry Santa Ana winds, low soil and vegetation moisture, and periods of scarce rainfall, creating optimal conditions for fire ignition and rapid spread. These fires not only burn plants, brush, and trees but also buildings, houses, and cars, releasing noxious gases and particulate matter that make wildfire smoke more toxic than normal air pollution. The smoke typically contains plastics, fuels, metals, and various chemicals, which have been linked to higher rates of heart attacks, strokes, cardiac arrests, and weakened immune systems. The concentration of fine particulate matter in the Los Angeles area during wildfire events can far exceed World Health Organization guidelines, posing a significant hazard to individuals with pre-existing lung and heart conditions, as well as the elderly and children.

The geography of Los Angeles, situated in a basin surrounded by mountains, further exacerbates the issue by trapping air pollution. The city often experiences marine inversions, a type of temperature inversion where warm air from the Great Basin or inland Los Angeles traps cooler ocean air near the Earth's surface, preventing polluted air from rising and dispersing. This phenomenon contributes to the elevated levels of air pollution observed during wildfire seasons.

The impact of wildfires on air quality in Los Angeles is significant, with smoke advisories issued during wildfire events and air quality reaching "unhealthy" to "hazardous" levels. The South Coast Air Quality Management District and the Los Angeles County Department of Public Health have reported that the city's air pollution levels still far exceed federal standards, with 1 in 10 children diagnosed with asthma and an increased overall risk of cancer. The California Air Resources Board, established in 1967, has been working to address air pollution through research and legislation, and significant improvements have been made over the last two decades. However, the long-term effects of wildfires on air quality in Los Angeles and the health of its residents remain a pressing concern.

Vehicular emissions and traffic congestion

Los Angeles, California, is notorious for its smog, a combination of particle and ozone pollution. The large population of 4 million in LA, with another 6 million in the surrounding county, contributes significantly to its ‘non-attainment’ air quality status because of heavy vehicular emissions and traffic congestion. LA is the third most economically powerful city in the world, with its shipping industry playing a huge part in its economic structure. The Port of Los Angeles and the Port of Long Beach are the two busiest container ports in the United States. Nearly 40% of the country's imports come through the LA area, transported by fossil-fuelled vehicles that release toxic particles into the atmosphere. The operation of these ports relies on fossil fuels or diesel to run ships, trucks, and other transportation, contributing to poor air quality.

Traffic congestion can greatly increase pollutant emissions and degrade air quality, particularly near large roadways. These emissions contribute to health risks for drivers, commuters, and individuals living near roadways, as shown by various studies and assessments. The California Air Resources Board's EMFAC2007 vehicle emission factors and meteorological data from the Long Beach Airport were used to estimate parcel-level PM2.5 concentrations from local traffic emissions within 3 kilometers of residences in summer and winter months. The model suggested that local traffic near the port complex contributes almost a quarter of the total fine PM in the study area.

Racial and ethnic disparities in traffic and vehicle particulate matter exposure have been observed in a major goods movement corridor near the Los Angeles-Long Beach Port Complex. After controlling for environmental and land use factors associated with traffic generation, a higher percentage of nearby Black and Asian/Pacific Islander residents were associated with higher exposure. In contrast, a higher percentage of Hispanic residents were associated with higher total vehicle miles travelled (VMT) exposure but lower vehicle particulate matter exposure. Lower socioeconomic status was associated with lower exposure, while higher socioeconomic status was associated with higher exposure.

During the early weeks of the COVID-19 pandemic, a dramatic drop in transportation and lockdowns worldwide resulted in a significant boost in air quality in many cities, including LA. A study by UCLA professor Yifang Zhu found that traffic reductions in LA were directly responsible for a 30% decrease in nitrogen oxides. However, when restrictions loosened and traffic rebounded, the short-term gains in air quality were quickly lost, and the return of driving, wildfires, and heat waves continued to impact the city's air quality.

LA's shipping industry and air pollution

Los Angeles, a major coastal city, is particularly vulnerable to air pollution from the shipping industry. Commercial ships burn fuel for energy and emit several types of air pollutants as by-products. These emissions have significant impacts on both public health and the climate.

Ship-source pollutants most closely linked to climate change and public health issues include greenhouse gases (GHG), nitrogen oxides (NOx), sulphur oxides (SOx), and particulate matter. In particular, nitrogen oxides contribute to smog formation, and sulphur oxides cause acid rain. These pollutants can have detrimental effects on both human health and the environment. For example, in Canadian coastal waters, acidification from sulphur oxides damaged the shells of clams and mussels, affecting the productivity of the aquaculture industry, and weakened coral structures, impacting their function as habitats for other species.

The shipping industry is a major contributor to global air pollution, and without action, its emissions are expected to increase. Globally, maritime shipping traffic is increasing, and ships are responsible for a significant proportion of nitrogen oxides and greenhouse gas emissions. In 2020, the marine shipping industry in Canada produced about 0.6% of the country's total GHG emissions. In the United States, California has taken steps to address this issue by requiring some large ships to use shore power while docked, with plans to increase electrification requirements through 2027.

To reduce air pollution from the shipping industry, several strategies have been proposed and implemented. These include technological improvements, operational changes, and market-based strategies. For example, the International Maritime Organization (IMO) implemented a regulation in 2020 that limited the amount of sulfur in fuel content, leading to a significant reduction in ship tracks, which are indicators of air pollution. The IMO has also set targets for reducing emissions and is developing new regulations to limit greenhouse gas emissions from ship fuel. Additionally, some of the industry's customers, such as Amazon, Unilever, and IKEA, have committed to using only zero-emissions cargo ships by 2040.

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