Air Pollution's Worst Offenders: Regions With Poor Indoor Air Quality

Air pollution is a significant global health problem, causing over 4.5 million premature deaths in 2019. While outdoor air pollution is a well-known issue, indoor air pollution is also a serious concern, causing an additional two million premature deaths in the same year. Indoor air pollution is influenced by various emission sources, such as ventilation, outdoor air quality, and specific indoor activities. The impact of poor air quality on human health is significant, ranging from respiratory issues to heart and lung diseases. The World Air Quality Report in 2024 highlighted that 91% of countries and regions exceeded the WHO's annual PM2.5 guideline value, with Central and South Asia among the most polluted regions. In the US, California, specifically the area around Bakersfield, has been identified as having the worst air pollution in the nation, with fine particulate pollution levels well above the EPA's threshold.

Industrial pollution

The natural gas, plastic, chemical, electric generation, and waste disposal industries can generate hazardous waste that, if not properly disposed of, can create significant air pollution. For example, the Clean Air Council has noted that every stage of oil and gas operations, from production and extraction to processing and distribution, releases air pollution that negatively affects public health and exacerbates climate change. Similarly, fracking-related infrastructure, steel-making plants, petrochemical plants, and hazardous waste sites can also contribute to air pollution.

In addition to air pollution, industrial activities have also been responsible for water pollution. The volume of wastewater discharged into water bodies has increased with the growth in production, and solid and liquid industrial wastes are finding their way into watercourses. This has disrupted marine biota and degraded water quality. Furthermore, the presence of marine microplastics has had adverse impacts on many marine species, especially high-profile megafauna such as marine birds, turtles, cetaceans, and fish.

The Clean Air Council works with communities and local governments to prevent hazardous industrial waste, oppose waste incineration, and advocate for extensive testing of waste streams to identify pollutants. They also call for a transition away from natural gas and single-use plastics, improved recycling, and the development of non-fossil fuel-based alternatives. These efforts are crucial, as industrial pollution has been linked to negative health outcomes, with air pollution being responsible for more than 10% of all deaths worldwide, according to The Lancet.

Poorly enforced regulations

While outdoor air pollution is a well-known issue, indoor air pollution poses an even greater threat to human health. Despite this, indoor air pollution is often overlooked and remains largely unregulated, with enforcement measures lacking in many parts of the world. Poorly enforced regulations can have detrimental consequences for public health and the environment.

In the United States, for example, while there have been significant improvements in outdoor air quality due to federal regulations such as the Clean Air Act of 1970, indoor air pollution remains outside the scope of these regulations. The Environmental Protection Agency (EPA) has set guidelines for outdoor air quality, but these do not extend to indoor spaces. This is a significant gap in protection, as indoor levels of pollutants can be two to five times higher than outdoor levels, and in some cases, even 100 times higher.

Gas stoves have been identified as a major source of indoor air pollution. In the US, there is no federal requirement for gas stoves to be vented outdoors, despite the fact that they can produce levels of pollution that would be considered illegal outdoors. This discrepancy in regulations has led to unsafe levels of carbon monoxide (CO) and nitrogen dioxide (NO2) in homes with gas stoves. While other indoor appliances, such as those burning fuel, are required to be vented outdoors, gas stoves are notably exempt from this regulation.

Canada's health agency has recognized the urgency of this issue and has begun to implement stricter guidelines for NO2 levels, both indoors and outdoors. However, enforcement of these guidelines remains a challenge, and it is not yet clear how effective they will be in practice. Additionally, while some US states, like California, have the authority to regulate indoor appliances through codes, the enforcement of these regulations is still a work in progress.

The lack of comprehensive and well-enforced regulations on indoor air pollution is a global issue. While emerging and developing countries may struggle to meet international environmental standards, even industrialized nations face challenges in regulating indoor air quality. This is partly due to the varied nature of indoor sources of pollution and the difficulty in monitoring and enforcing guidelines within private residences. As a result, the responsibility for managing indoor air quality often falls on individuals, who may not have the necessary knowledge or resources to effectively improve the air they breathe within their own homes.

Wildfires

While I cannot find specific information on which region has the worst indoor air pollution, I can tell you that wildfires can significantly impact indoor air quality.

The health effects of breathing in wildfire smoke can be serious. The microscopic particles in smoke can enter the eyes and respiratory system, causing irritation and potentially leading to illnesses such as bronchitis. People with existing respiratory conditions may be particularly vulnerable to the effects of wildfire smoke.

If you are in an area affected by wildfires, it is essential to take precautions to protect yourself and your family. Stay informed about the fire's location and scale by following local news, emergency alerts, and official websites. If advised to evacuate, do so immediately. To reduce smoke exposure, keep windows and doors closed, and use air purifiers or HVAC systems with a fresh air intake set to recirculate mode. In addition, wear an N95 pollution mask when going outdoors, as these masks are effective against particle pollution.

You can also refer to resources provided by organizations such as the US Environmental Protection Agency (EPA), which offers guidance on creating clean rooms, DIY air cleaners, and managing indoor air quality during wildfire smoke events.

Poor ventilation

Indoor air pollution arises from various sources, including outdoor contaminants, human activities, and specific indoor emission sources. Outdoor contaminants like diesel emissions from busy highways, coal-burning factories, and wildfire smoke can easily permeate indoor spaces. Additionally, human activities, such as cooking, painting, and using chemicals, release pollutants that accumulate indoors without proper ventilation.

Specific indoor emission sources also play a role in poor indoor air quality. Fuel-burning appliances, including cooking stoves, furnaces, and water heaters, emit harmful pollutants. Incomplete combustion and poor ventilation of these appliances can further exacerbate the issue. Similarly, construction processes and products, such as glues, off-gassing from carpets, and emissions from particleboard, contribute to indoor air pollution.

To mitigate poor ventilation and improve indoor air quality, several strategies can be employed:

• Source Control: Identify and eliminate or minimize known sources of indoor air pollution. For example, avoid smoking indoors or near entrances, and ensure proper ventilation when using fuel-burning appliances or during construction or renovation projects.
• Ventilation: Open windows and use fans to promote air circulation. Exhaust fans in bathrooms and kitchens are particularly effective at removing moisture and pollutants. Ceiling fans and portable window fans can also improve airflow.
• Air Cleaning: When indoor air pollution persists, consider using air purifiers or high-efficiency HVAC filters to remove fine particles from the air.
• Duct Sealing: Seal ductwork to minimize the spread of pollutants from one area to another and to prevent the build-up of excessive moisture, which can lead to mold growth.
• Air Conditioning (HVAC) Systems: Ensure regular maintenance of HVAC systems to prevent contamination and the spread of pollutants. Set the system to recirculate mode during periods of poor outdoor air quality.
• Masks: In cases of hazardous indoor air quality, masks, particularly those with pollution filters like N95 masks, can provide protection against particle pollution.

While outdoor air generally has fewer pollutants than indoor air, it is important to be mindful of outdoor air quality when improving indoor ventilation. Avoid excessive ventilation during periods of poor outdoor air quality, especially if you live near busy highways, industrial areas, or wildfire-prone regions.

Outdoor air pollution

The World Health Organization's (WHO) Global Air Quality Guidelines (AQG) provide guidance on thresholds and limits for key air pollutants that pose health risks. The AQG also offers interim targets to promote a gradual shift towards lower pollutant concentrations, which could save around 300,000 lives annually. Despite these efforts, the number of deaths from outdoor air pollution has increased in most countries, driven by population growth and aging populations.

Particulate matter (PM), particularly PM2.5, is a critical indicator of air pollution. These fine particles, measuring 2.5 micrometres or less in diameter, can be absorbed into the bloodstream when inhaled. The major components of PM include sulfates, nitrates, ammonia, sodium chloride, black carbon, mineral dust, and water. Other harmful pollutants include carbon monoxide (CO), ground-level ozone (O3), and nitrogen dioxide (NO2), which is released during fuel combustion in the transportation and industrial sectors.

The burden of outdoor air pollution disproportionately affects low- and middle-income countries, with 89% of premature deaths occurring in these regions. The greatest burden is found in the WHO South-East Asia and Western Pacific Regions. This is due to the increased industrialization and the shift from low to middle incomes experienced by these regions. Additionally, indoor pollution rates tend to be high in low-income countries due to the reliance on solid fuels for cooking.

To address outdoor air pollution, concerted action is required from policymakers in sectors like energy, transport, waste management, urban planning, and agriculture. Implementing policies and investments that support cleaner transport, energy-efficient homes, improved power generation, and better municipal waste management can significantly reduce outdoor air pollution and protect public health.

Frequently asked questions