Yesterday, sandstorms broke out in many places such as Beijing and Jinan. The whole city covered the sun with yellow sand, and people seemed to be walking on Mars.
Some netizens also added a little special effects to the street videos, and it seems that it is much more reasonable:
The impact of haze on human health
Recent sandstorms have caused the air quality to decline in many areas and the number of haze days has increased significantly. Everyone is trying every means to prevent haze. Air pollution does have many potential effects on our health, from subtle physiological changes to obvious physical symptoms. Environmental epidemiological studies have found that air pollution is closely related to a variety of health hazards, including pulmonary hypofunction, respiratory diseases, chronic bronchitis, cardiovascular and cerebrovascular diseases, early death caused by outpatient visits.
According to the World Health Organization's Global Health Risks report published in 2009, urban outdoor air pollution has been listed as the 14th largest risk factor for the global death toll in 2004 (the top five are hypertension, tobacco use, hyperglycemia, lack of exercise, overweight and obesity).
Outdoor air pollution can also increase the risk of cancer. In 2012, the International Cancer Research Agency listed the exhaust gas produced by diesel engines from "possible carcinogens (Class 2A)" as "human carcinogens (Class 1)". Based on the latest research evidence, the agency further listed air pollution as a human carcinogen in 2013 (Category 1).
Common air pollutants include suspended particles, carbon monoxide, nitrogen dioxide, sulfur dioxide , ozone, lead, etc. Among them, the suspended particles can be distinguished according to their aerodynamic equivalent diameter. For example, PM2.5 is particulate matter with a diameter of less than 2.5 microns, and PM10 is particulate matter with a diameter of less than 10 microns. The former is more harmful because it can penetrate deep into the lungs after inhalation, causing various health effects, such as increasing respiratory symptoms, weakening lung function, causing chronic bronchitis, and damaging the cardiovascular system.
According to the World Health Organization report: exposure to air pollution, especially to fine particles (PM2.5), is an important risk factor for myocardial infarction, stroke, chronic obstructive pulmonary disease and cancer. Of the deaths caused by outdoor air pollution, 80% died from heart disease and stroke, and 20% died from respiratory diseases and cancer. The various physiological functions of the elderly are gradually weakening, and many of them suffer from cardiovascular and respiratory diseases. They are susceptible to smog weather. They should try to avoid going out on days with severe air pollution.
Children are also susceptible to haze weather. Overall, compared with adults, children spend more time outdoors, exercise more intensely, and relative to their size, children inhale more air per minute, which causes them to absorb more suspended particles per unit of lung surface area, increasing the adverse effects of haze on the lungs.
If the child breathes heavily polluted air for a long time, the chance of suffering from asthma will increase; for children who already suffer from asthma, air pollution may aggravate their condition. Studies have found that even if is exposed to PM2.5 for a short period of time, it may lead to increased respiratory symptoms, decreased lung function and increased medication in children with asthma.
Ultra-fine suspended particles can even easily enter the brain via sensory neurons from the respiratory tract, and from the distal alveoli to the blood or lymph. Since childhood and adolescents are critical periods of brain development, some researchers believe that exposure to air pollution in children and adolescents may affect their behavior, cognition and lead to emotional changes.
In addition to suspended particles, other air pollutants, such as lead, can also have an adverse impact on children's health. Young children are particularly susceptible to the toxicity of lead, especially lead, which can affect brain development, resulting in decreased IQ, shortened attention time, and decreased academic performance, and the neurological and behavioral effects brought by lead are irreversible. Studies have found that compared with adolescents and adults, the blood concentration of children is more likely to be affected by the lead concentration in the surrounding air.
The impact of outdoor air pollution on pregnant women and fetus
Among the many harms of haze, there is one health hazard that may not be thought of immediately, that is, the health impact on the baby in the mother's belly, especially low birth weight (i.e., the birth weight of a newborn is less than 2.5 kg). There is growing evidence that mothers are exposed to air pollution during pregnancy may affect their baby's birth weight and some other pregnancy outcomes.
Many domestic and foreign studies have found that mothers live in areas with heavy air pollution during pregnancy, they are more likely to give birth to lighter babies. One of the studies was from Beijing and was published in the 2015 journal "Environ Health Perspect". This study is based on a rare and special opportunity: a brief decline in air pollution levels during the 2008 Beijing Summer Olympics and Paralympics.
As we all know, Beijing is one of the most severe air pollution cities in my country, and the reasons for poor air quality include motor vehicle exhaust emissions, industrial production, coal burning, etc. In the months leading up to and during the 2008 Beijing Olympics and Paralympics, Beijing has taken a series of strong measures to improve air quality, such as strictly enforcing vehicle emission standards, vehicle restrictions, relocation and closing factories in Beijing and some surrounding provinces, and cessing construction projects. In this way, from June to October 2008, Beijing's air quality has improved significantly, and the concentrations of many air pollutants, including PM2.5, nitrogen dioxide, carbon monoxide, sulfur dioxide, sulfate, etc., have decreased by 18 to 59% compared with the pre-Olympic level. But after the Olympics, the concentration of these pollutants began to gradually rebound.
is the comparison of air pollutants before and after the Olympics, providing researchers with a unique opportunity for "natural experiments". A scientific research team composed of Chinese and American researchers conducted statistical analysis on the birth records of 71,803 full-term newborns (gestation ages of 37 to 41 weeks) in Beijing Obstetrics and Gynecology Hospital from 2007 to 2010. The mothers of these newborns were from Xicheng District, Haidian District, , Fengtai District, or Chaoyang District, . The study found that pregnant women who were in their 8th month of pregnancy during the Beijing Olympics had a heavier weight than the average weight of babies born in the same period in 2007 or 2009, with an increase of 23 grams.
Why do research results show that air quality is most closely related to the eighth month of pregnancy (rather than other months)?
researchers said that further exploration is needed to find out the reasons. One possibility is that the fetus grows fastest in the late pregnancy, and this stage when exposed to air pollutants may affect certain physiological mechanisms, such as the ability of the placenta to provide nutrients, thereby hindering fetal growth. Therefore, from August 8 to September 24, 2008, a total of 47 days. Although the improvement of air quality was short, the quality improvement was significant, and it still brought growth benefits of 23 grams to the fetus who were eight months old at that time.
Another possibility is that the early months of pregnancy are also important. Although mothers who are in the early stages of pregnancy during the Olympics have also caught up with the good air at that time, their benefits to fetal growth may be covered up or offset by the harm of air pollution after the Olympics.
researchers believe that if the air quality improves for a longer period of time, such as lasting for several months or even the entire pregnancy, the baby's birth weight may be more obvious.
There are also many researches in this area abroad. A comprehensive analysis of data from more than 74,000 women in 12 European countries also found that air pollution is closely linked to low birth weight (2.5 kg) for full-term babies. The study results show that if increases 5 micrograms per cubic meter of PM2.5, the risk of low birth weight increases by 18%. EU countries stipulate that the annual average concentration of PM2.5 must not exceed 25 micrograms per cubic meter, but this study found that even if PM2.5 is below this value, the risk of low birth weight will still increase with the increase in the concentration of pollutants. Therefore, it was suggested that EU countries should further lower the PM2.5 standard.
In addition, the study also found that traffic density near the place of residence of pregnant women is also related to the risk of low birth weight.If the residence is near the street, the risk of low weight in newborns increases by 6%.
Another meta-analysis that combines birth data from approximately 3 million babies in nine countries, including North America, South America, Europe, Asia and Australia, also found the association between outdoor air pollution and fetal development: pregnant women inhaled PM2.5 and PM10, the higher the probability that their newborn baby weighs less than 2.5 kg. This study even found a linear relationship between PM10 and birth weight: for every 10 micrograms/cubic meter increase in PM10, the baby's birth weight decreases by 8.9 grams (95% confidence interval: -13.2, -4.6 grams).
has many researchers pay attention to birth weight because it is an important reference indicator for measuring the health of newborns. Low birth weight can bring a range of near-term and long-term health problems to the baby, including a higher likelihood of complications or even death within a few weeks after birth, as well as chronic disease problems during growth and adulthood, such as increased risk of obesity, diabetes, hypertension, etc.
Of course, the heavier the newborn, the better. If you are overweight at birth (≥ 4 kg), the chances of the mother having to undergo a cesarean section increase and the risk of postpartum bleeding increases. Moreover, babies are more likely to be obese and develop cardiovascular diseases when they grow up.
In fact, the adverse effects of air pollution on the fetus are far more than the indicator of birth weight. My colleagues and I have systematically reviewed 25 domestic studies on outdoor air pollution and some adverse pregnancy outcomes (low birth weight, premature birth, death and congenital malformations). We found that sulfur dioxide is related to low birth weight and premature birth; PM10 is more closely related to congenital malformations, especially congenital cardiovascular defects. However, the existing evidence is not enough to explain the association between exposure to air pollutants during pregnancy and neonatal death.
What can we do in the face of air pollution?
The environment is difficult to change, so we can only try to reduce the intensity of outdoor activities and shorten the time we stay outdoors on days when the air pollution is severe. If outdoor activities are unavoidable, someone will choose to use a mask.
Although surgical masks and cotton masks can filter larger suspended particles , studies have shown that neither type of mask can effectively filter suspended particles (PM10) with aerodynamic equivalent diameter below 10 microns, and it cannot block suspended particles (PM2.5) with a diameter below 2.5 microns. So, there is no doubt that neither surgical masks nor cotton masks can provide children with anti-smog protection.
surgical masks have little effect on anti-smog
The anti-smog masks that many people are more familiar with are N95 masks. It refers to a class of masks that meet the standards of the NIOSH (National Institute of Occupational Safety and Health) that block at least 95% of particulate matter with a diameter of 0.3 microns (PM2.5 is 2.5 microns) . After testing, if worn correctly and close to the face, this type of mask has a good filtering effect and can filter out most of the PM2.5.
Some studies conducted in my country have shown that the use of N95 masks can reduce the adverse effects of air pollution on blood pressure and heart rate. For example, in a study from Beijing, researchers asked 98 patients with coronary heart disease to walk along the route set by the study, some of whom wore N95 masks, while others did not. During the study period, patients' disease symptoms, exercise status, personal air pollution exposure, blood pressure, heart rate, and electrocardiogram were monitored. results found that patients wearing N95 masks had better blood pressure and heart rate variability than those in the non-wearing group.
M: N95
N95 masks are available in many different brands, such as 3M is a brand that everyone is more familiar with. The functions of N95 masks of different brands of are similar, and the differences are generally only in color, size and style.
Although N99 and N100 have better theoretical filtering effect, there is actually no need to blindly pursue better values, but you still have to consider whether it can fit well with your face. If the mask does not fit the face well, the mask will not achieve the ideal protective effect.
Another common anti-smog mask is EN-149. The difference between it and N95 is that N95 passes the US NIOSH certification, while EN-149 complies with European standards.
M: EN-149According to the ability to filter suspended particles in the air (at 95L/min airflow), EN-149 can be divided into three categories:
FFP1: filters 80% of air suspension particles
FFP2: filters 94% of air suspension particles
FFP3: filters 99% of air suspension particles
It can be seen that FFP2 masks that meet the European EN-149 standards have the closest filtering capacity to N95 masks.
N95 and EN-149 masks can effectively block suspended particles in the air. When we choose, we mainly look at whether they fit well with the face. But the problem is that, whether N95 or EN-149, they were designed for adults at the beginning and it was difficult to fit the face shape of a child. When children wear it, if the air keeps leaking through the gaps that don’t fit, the effect of the anti-smog mask will be greatly reduced. Therefore, it is very important to find an anti-smog mask suitable for children to wear.
Some companies have produced anti-smog masks suitable for small faces or for children. However, it should be noted that there is currently no set of certification standards for children's anti-smog masks. You can only choose masks that meet N95 or EN-149 standards and are sized to fit the shape of the child's face.
Indoor air pollution should not be underestimated
Although outdoor air pollution may have adverse effects on children's health, indoor air quality is equally important, especially be careful not to let children smoke second-hand smoke.
When the outdoor air PM2.5 reaches 100 micrograms per cubic meter, the total air pollutants that people can inhale outdoors for 24 hours are 1100 micrograms. But you can inhale 10,000 to 40,000 micrograms of PM2.5 suspended particles by just taking the initiative to smoke one cigarette. Therefore, the harm caused by indoor second-hand smoke to children should not be underestimated.
Outdoor activities on smog days
At present, it is difficult to find anti-smog masks suitable for young children (5 years old) (note meaning: babies cannot use masks indoors and outdoors). When PM2.5 is 101-150, the best way is to reduce physical consumption and activities and outdoor activities; older and healthy children can perform outdoor activities, but they should reduce long-term strenuous exercise.
If PM2.5 is between 151 and 200, it is recommended that children stay indoors and reduce physical consumption; older children need to avoid long-term and vigorous exercise, and should also increase rest time when performing other outdoor activities.
If PM2.5200, children should immediately stop outdoor activities and stay indoors.
neither surgical mask nor cotton mask can block tiny suspended particles (PM10 and PM2.5) nor can they completely protect children from germs. If you choose to let older children use anti-smog masks, you should choose a child-specific one and try to choose the style that fits most with their faces to achieve the best anti-smog effect.
At the same time, should also pay attention to whether the child has symptoms such as dizziness, difficulty breathing after wearing it for a period of time. Once it occurs, it needs to be suspended. Children with chronic heart disease and lung problems have different tolerance to anti-smog masks. If the child experiences discomfort when wearing the mask, he or she needs to consult a professional doctor for further consultation.
References:
. World Health Organization, Sixty-Eighth World Health Assembly, Health and the Environment: Responding to the Health Impacts of Air Pollution, http://apps.who.int/gb/ebwha/pdf_files/WHA68/A68_18-ch.pdf. Zhang S, Li L, Gao W, Wang Y, Yao X, Interventions to reduce individual exposure of elderly individuals and children to haze: a review, J Thorac Dis 2016; 8(1): e62-8.. World Health Organization, Lead Poisoning and Health, http://www.who.int/mediacentre/factsheets/fs379/zh/. Langrish JP, Li X, Wang S, et al. Reducing personal exposure to particular air pollution improves cardiovascular health in patients with coronary heart disease. Environ Health Perspect. 2012;120(3):367-72.. U.S. Food Drug Administration, Masks and N95 Respirators, https://www.fda.gov/MedicalDevices/Products and MedicalProcedures/General HospitalDevices and Supplies/PersonalProtective Equipment/ucm055977.. Ministry of Health Singapore, FAQ: Use of masks and availability of masks, https://www.moh.gov.sg/content/moh_web/home/pressRoom/Current_Issues/2014/haze/faq--use-of-masks-and-availability-of-masks.html- . Taiwan Executive Yuan Environmental Protection Department, Air Quality Indicators and Activities Recommendations, https://taqm.epa.gov.tw/taqm/tw/b0201.html
- . Hong Kong Department of Health, Impact of Air Pollution on Health. http://www.chp.gov.hk/tc/content/9/460/3557.html . Rich DQ, Liu K, Zhang J, Thurston SW, et al. Differences in birth weight associated with the 2008 Beijing Olympics air pollution reduction: results from a natural experiment. Environ Health Perspect, 2015, 123(9): 880-7.
0. Pedersen M, Giorgis-Allemand L, Bernard C, et al. Ambient air pollution and low birthweight: a European cohort study (ESCAPE), The Lancet Respiratory Medicine. 2013, 1(9): 695-704.1. Dadvand P, Parker J, Bell ML, et al. Maternal exposure to particular air pollution and term birth weight: a multi-country evaluation of effect and heterogeneity. Environ Health Perspect, 2013, 121(3): 267-373.2. Jacobs M, Zhang G, Chen S, et al. The association between ambient air pollution and selected adverse pregnancy outcomes in China: A systematic review. Sci Total Environ, 2017, 579:1179-1192.If you like, please forward and share:)
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