Impact of air pollution on lung cancer

WHO has classified outdoor air pollution as a class I human carcinogen. Exposure to air pollutants for a long time can be fatal as it is associated with an increased number of lung cancer cases. air pollution exposures after lung cancer diagnosis shorten survival. 

Relevant published articles:

1. //www.ncbi.nlm.nih.gov/pmc/articles/PMC4198750/

2. //www.ncbi.nlm.nih.gov/pmc/articles/PMC5400105/

Air pollution is a big problem, especially for the growing generation. if we talk about air pollution in India, then there is a lot of policy gap, lack of strategy. In fact, it is limited to Delhi, NCR only. No news channel, reporting agencies focusing on another part of India. 

there are types of air pollution, not all air pollutants cause damage to the lungs. Nitrogen dioxide: a gas that can irritate the airways and cause a flare-up of asthma or COPD. Ozone: a gas that can reduce lung capacity and irritate the airways.

Emissions from industries, transportations and burning of domestic waste contribute to the air pollution and now it has exceeded the World Health Organization's health-based air-quality guidelines. Outdoor air pollution is a global public health challenge as it has many adverse effects on the human health. It is also a major contributor to the burden of diseases worldwide. There are human, experimental and mechanistic evidence which supports the causal link between ambient air pollution, particularly particulate matter with lung cancer incidence and mortality lung cancer deaths. Multilevel public health and policy interventions are required for cancer prevention and further research is required to understand the impact of outdoor air pollution on morbidity and mortality patterns after lung cancer diagnosis.

Read here: //acsjournals.onlinelibrary.wiley.com/doi/full/10.3322/caac.21632

Cancer is one the major public health issue, of which, lung cancer constitutes the major cause of cancer incidence and mortality (1). Evidence also shows that indoor and outdoor air pollution in addition to asbestos, radon, and arsenic exposure, are the independent risk factors associated with it. This paper (2) examines the relationship of long-term low-level air pollution exposure and lung cancer incidence. Positive association between exposure to long term ambient PM2.5 and lung cancer was found even at concentrations below the EU limit values and WHO Air Quality Guidelines. 

References

1. //acsjournals.onlinelibrary.wiley.com/doi/10.3322/caac.21660
2. //www.sciencedirect.com/science/article/pii/S0160412020322042#b0045

During a typical days average adults inhales about 10000 litrs of air .Consequently, even the carcinogens present in the air at low concentration are of concern a risk factors for lung cancer in large population .Outdoor air can contain a number of hazardous agents and many of them are generated by fossils fuels ,including carcinogens such as polycyclic aromatic hydrocarbons and metals such as arsenic ,nickel and chromium . Depending on pollution sources the constituents of air pollution vary by locale and overtime .Particulate matter which has multiple sources in urban areas air .Nevertheless the results are impressive and highlight the importance of improving air quality ,even below current threshold values .Although additional gene environment interaction these needed to specific identification highest priority should be enforceable societal level actions to reduce exposure to air pollution globally .The most effective public health policy is to protect those among us who are more vulnerable .

REFERENCES :- //www.ncbi.nlm.nih.gov/pmc/articles/PMC8528534/

The effect that air pollution has on the lungs depends on the type and concentration of pollutants present in the air. Exposure to high pollution levels can cause irritated airways, dyspnoea and coughing. Lung cancer is mainly linked to the fine particulate matter present in air that can enter deep into the lungs, and even more research needs to be done on the precise way that these particles start the cancerous process within the lungs. Particulate pollution enhances the risk of early aging and death, heart disease and asthma attacks, and it can also interfere with the growth and function of the lungs. Also, general ambient air pollution due to the incomplete combustion of fossil fuels, leading to rise in harmful carcinogens may be responsible for increased rates of lung cancer. 

References:

1. //www.lung.org/blog/lung-cancer-and-pollution
2. //www.blf.org.uk/support-for-you/air-pollution/effects
3. //www.ncbi.nlm.nih.gov/pmc/articles/PMC8528534/
4. //www.ncbi.nlm.nih.gov/pmc/articles/PMC1518961/

Lungs are vital organs for respiration and lung cancer has become too common globally since 1940s.Its symptoms are seen only at advanced stage of the disease. Air pollution is a major factor for respiratory diseases. It is closely associated with asthma, COPD, bronchiectasis and lung cancer. Air pollution is supposed to be human carcinogen and it is on the increase in Asia, Africa, Mexico and Central America. It poses an urgent worldwide challenge to public health.

Both indoor and outdoor air pollution are injurious to health and more specifically for lungs. Overwhelming evidence shows that air pollution caused by exhaust from motor vehicles and industries carries particulates. Tiny particulates are more dangerous than large ones as they enter deep into the lungs and damage DNA in cells causing lung cancer. Particle pollution can also interfere in the growth and function of lungs. Radon, indoor air pollution too causes lung cancer.

The effect of air pollution causing lung cancer depends on:

• Types and mix of pollutants
• Concentration of pollutants
• How much of particulate penetrates the lungs
• Period of exposure to air pollution

Indoor air pollution caused by cooking using kerosene, firewood and charcoal has carcinogen is also a major cause for lung cancer. Particulate matter inhaled from household air pollution results in deaths due to pneumonia among children below 5 years of age. In poorly ventilated dwellings, air pollution is higher while cooking with solid fuels.

To minimize lung cancer due to particulate air pollution, the American Lung Association suggests that-

• Air pollution forecasts in your area should be checked daily
• When there is heavy air pollution, walking or jogging should be avoided
• Limited use of energy indoor and on road
• Avoid burning firewood as it emits soot polluting air
• Healthy air campaigns to be organized as responsible citizens to bring awareness in urban areas
• Making multiple trips by motor vehicles may be curtailed
• Avoid thrash burning in the public
• Wearing masks are suggested in an air polluted zone.

When there is substantial evidence from studies conducted to support the link between particulate matter in air and incidence of deaths due to lung cancer, multi-level interventions aimed at individual and global level becomes mandatory.

Citation

1. Higgins IT. Air pollution and lung cancer: diesel exhaust, coal combustion. Prev Med. 1984 Mar;13(2):207-18. doi: 10.1016/0091-7435(84)90052-5. PMID: 6204329.

2. Cohen AJ, Pope CA 3rd. Lung cancer and air pollution. Environ Health Perspect. 1995 Nov;103 Suppl 8(Suppl 8):219-24. doi: 10.1289/ehp.95103s8219. PMID: 8741787; PMCID: PMC1518961.

Reference

//www.cancerresearchuk.org/about-cancer/causes-of-cancer/air-pollution-radon-gas-and-cancer/how-can-air-pollution-cause-cancer

Air pollution is the second leading cause of lung cancer in the world, after smoking according to a new analysis on the causes of lung cancer. Most of the global population resides in places where air pollution levels, because of emissions from industry, power generation, transportation, and domestic burning, considerably exceed the World Health Organization's health-based air-quality guidelines. A causal link between outdoor (ambient) air pollution, and especially particulate matter (PM) in outdoor air, with lung cancer incidence and mortality, has been substantially identified in recent studies. It is estimated that hundreds of thousands of lung cancer deaths annually worldwide are attributable to PM air pollution. Epidemiological evidence on outdoor air pollution and the risk of other types of cancer, such as bladder cancer or breast cancer, is more limited. Major primary air pollutants, those emitted directly into the environment largely as a result of the combustion of fossil and biomass fuels, include gaseous pollutants (such as sulfur dioxide [SO₂], nitrogen dioxide [NO₂], carbon monoxide [CO], and volatile organic compounds [VOCs]) and particulate matter (PM) (including carbonaceous aerosol particles, such as black soot). Although CO levels are often low outdoors in the developed world today (because of the use of emission controls such as catalytic converters on automobiles), high levels can be experienced near biomass burning sources, including wildfires. In addition, secondary air pollutants are formed in the atmosphere from primary pollutants and include gaseous ozone (O₃), a major component of photochemical smog, formed in the atmosphere when nitrogen oxides (NO_x) and hydrocarbons such as VOCs react in the presence of sunlight. Similarly, particulate sulfate (eg, sulfuric acid [H₂SO₄]) and nitrate (eg, ammonium nitrate [NH₄NO₃]) aerosols are commonly created in the atmosphere from SO₂ and NO_x, respectively. Primary combustion particles and secondary particles are small in diameter and are often referred to as fine particulate matter, or PM_2.5 (particles ≤2.5 µm in aerodynamic diameter). Submicron combustion-related PM_2.5 is of particular health concern because it contains numerous toxic compounds (eg, acids and heavy metals), and can penetrate deeper into the lung than the larger PM generated by natural processes, such as most windblown soil particle mass.

Lung cancer is the most commonly diagnosed cancer worldwide and is the leading cause of cancer death, with an estimated 2.1 million new cases and 1.8 million deaths occurring in 2018, representing 11.6% of all new cancer diagnoses and 18.4% of all cancer deaths. In the United States, approximately 234,030 new lung cancer cases, and 154,050 deaths were estimated in the same year. Lung cancer is highly fatal, with an overall 5-year survival rate of only 18%. Rates of lung cancer incidence and mortality vary substantially within and between countries, depending largely on historical patterns of cigarette smoking, with long latency periods of up to approximately 30 years between the start of the smoking epidemic and the rise of lung cancer incidence. On the basis of sufficient evidence in studies of humans and experimental animals, as well as strong mechanistic evidence, the International Agency for Research on Cancer (IARC) in 2013 classified both outdoor air pollution and PM in outdoor air pollution as Group 1 human carcinogens for lung. In the introduction to their landmark report on the preliminary findings of their case-control study of lung cancer in London, Doll and Hill commented in 1950 that 2 main causes had been put forward: 1) general atmospheric pollution from automobile exhaust and surface dust from tarred roads and from gas works, industrial plants, and coal fires; and 2) smoking tobacco. In the ensuing 70 years, the dominance of tobacco smoking as a cause of lung cancer perhaps distracted attention away from the role of outdoor air pollution as another avoidable cause.

Mortality attributable to PM_2.5 depends not only on patterns in ambient pollutant levels but also on other factors, including underlying population dynamics, aging, mortality rates, access to health care, and other racial and socioeconomic disparities, and, as such, the number of estimated attributable lung cancer deaths has increased by nearly 30% since 2007. These factors may also explain, at least in part, the wide variation in country-specific estimates. Age-standardized PM_2.5-attributable lung cancer mortality rates and population-attributable fractions in the United States, for example, were 1.6 per 100,000 (95% UI, 0.65-2.91 per 100,000) and 4.7% (95% UI, 1.9%-8.5%) compared with 7.4 per 100,000 (95% UI, 5.4-9.5 per 100,000) and 20.5% (95% UI, 14.8%-25.9%) in China.

references:

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//acsjournals.onlinelibrary.wiley.com/doi/10.3322/caac.21632#caac21632-bib-0003

//acsjournals.onlinelibrary.wiley.com/doi/10.3322/caac.21632#caac21632-bib-0016

//thorax.bmj.com/content/58/12/1010

//www.ncbi.nlm.nih.gov/pmc/articles/PMC1518961/